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Transcript
UNESCO-NIGERIA TECHNICAL &
VOCATIONAL EDUCATION
REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN
SCIENCE LABORATORY TECHNOLOGY
TAXONOMY OF LIVING ORGANISMS
COURSE CODE: STB 111
YEAR I- SE MESTER I
THEORY
Version 1: December 2008
1
TABLE OF CONTENTS
WEEK 1: General Classification of Living Organisms………………………………………3
WEEK 2: General Classification of The Plant Kingdom……………………………………..11
WEEK 3: Classification of Algae……………………………………………………………….15
WEEK 4: Classification of Fungi……………………………………………………………….19
WEEK: 5 Classification of Bryophyta…………………………………..……………………...22
WEEK 6: Classification of Spermatophyta……………………………….……………………26
WEEK 7 : Common Flowering Plant (Monocotyledonous Plant Families)….………………31
WEEK 8: Family Bambacaceae…………………………………………………..…………….37
WEEK 9: Technique For Collecting and Preserving Common Flora (Herbarium)……..….42
WEEK 10: General Classification of the Animal Kingdom……………………………………46
WEEK 11: Phylum Chordata…………………………………………………………………….64
WEEK 12: Class Amphibia ………………………………………………………………………67
WEEK 13: External Features of a Tilapia ……………………………………………………...71
WEEK 14: Protochordates as A Link Between Invertebrates And Vertebrates ………….…76
WEEK 15: Preservation Methods of Common Vertebrates and Invertebrates ……….........78
2
WEEK 1: GENERAL CLASSIFICATION OF LIVING ORGANISMS
1.0 Introduction
The classification of living organisms has been controversial throughout time.
Aristotle’s system distinguished only between plants and animals on the basis of
movement, feeding mechanism, and growth patterns. In 1735 the Swedish
naturalist Carolus Linnaeus formalized the use of two Latin names to identify
each organism, a system called binomial nomenclature. He grouped closely
related organisms and introduced the modern classification groups: kingdom,
phylum, class, order, family, genus, and species. Single-celled organisms were
observed but not classified.
In 1866 German biologist Ernst Haeckel proposed a third kingdom, Protista, to
include all single-celled organisms. Some taxonomists also placed simple
multicellular organisms, such as seaweeds, in Kingdom Protista. Bacteria,
which lack nuclei, were placed in a separate group within Protista called
Monera.
In 1938 American biologist Herbert Copeland proposed a fourth kingdom,
Monera, to include only bacteria. This was the first classification proposal to
separate organisms without nuclei, called prokaryotes, from organisms with
nuclei, called eukaryotes, at the kingdom level.
In 1957 American biologist Robert H. Whittaker proposed a fifth kingdom,
Fungi, based on fungi's unique structure and method of obtaining food. Fungi do
not ingest food as animals do, nor do they make their own food, as plants do;
rather, they secrete digestive enzymes around their food and then absorb it into
their cells.
Below is the present classification system currently in use:
3
Monera
Protista
(Prokaryote)
Fungi
Plantae
Animalia
Unicellular Multicellular
Green
Multicell
Eukaryotes Eukaryotes
Multicell
Animals
1.1 Plant Kingdom
The kingdom Plantae accounts for the largest proportion of the
earth’s biomass with its approximately 250,000 species of mosses,
liverworts, ferns, flowers, bushes, vines, trees, and other plants.
Aquatic and terrestrial plants are the basis of all food webs. They
contribute life-supporting oxygen to the atmosphere and provide
humans with the fossil fuels, medicines, and other substances so
important to our present existence.
Figure 1 Typical Picture of Rain Forest
4
1.2 Plant Classification
The first scientific study of plants was the attempt to classify them. At first,
because of the limited knowledge of plant structures, artificial classifications,
beginning with the most ancient one into herbs, shrubs, and trees, were
necessary. These simple categories merely cataloged, in a tentative way, the
rapidly accumulating material, in preparation for a classification based on
natural relationships. Modern taxonomic classification, based on the natural
concepts and system of the Swedish botanist Carolus Linnaeus, has progressed
steadily since the 18th century, modified by advances in knowledge of
morphology, evolution, and genetics.
Thus, taxonomy is concerned with the description, identification and naming of
plants and their classification into groups based on resemblances and
differences mainly in their morphological, reproductive and anatomical
characteristics.
The objectives is to describe, name and classify plants is such away that their
evolutionary trend is brought out i.e. from simpler, earlier and more primitive
types to more complex, more recent and more advanced types.
The earlier classification of plants were based on either economic value e.g.
cereal, medicinal, fibre yielding, oil yielding fruits, vegetables etc or on gross
structural resemblance e.g. herbs, shrubs trees, climbers etc. Plants that do not
fit into such classification were usually ignored
1.3 Types of system of classification
There are two Types of system of classification, these are:
Artificial system of classification and Natural system of classification.
1.3.1 Artificial system of classification
In Artificial system of classification, one or few characters are arbitrary selected
and plants are arranged into groups according to these characters. Related plants
5
are often placed in different groups. Unrelated plants are put in same group
because of the absence or presence of a particular character.
This system does not indicate the natural relationship that exist among the
individuals of a group. Nevertheless, the identification of an unknown plant is
rendered much easier by this system.
1.3.2 Natural system of classification
In Natural system of classification all important characters are taken into
consideration. Initially, only morphological and anatomical characters are
considered and plants are grouped according to these characters. Later,
cytological, reproductive, physiological, genetic characters are taken into
consideration including the geographical distribution of the plant.
Plants are first classified into few large groups. These are further divided and
sub-divided into smaller groups until the smallest group is reached (i.e species).
This system gives a true idea of natural relationship existing between the
different plants.
The natural system has two main aspects i.e Systematics and Nomenclature.
Systematics
This is concerned with putting plants into groups. The smallest group is the
“SPECIES’ which is defined as a group of individuals having a close
resemblance with one another structurally and functionally. The members
belonging to the species can interbreed in nature freely and successfully among
themselves to give rise to progeny of the same kind. However, there is no sharp
demarcation between allied species.
The collection of species which bear close resemblance to one another form a
GENUS. For example, Fig (Ficus carica), Banya (Ficus bengalensis) and
Peepul (Ficus religiosa) are different species but are allied because they
6
resemble one another in their reproductive organs-inflorescence, flower, fruit
and seed. The genus name is Ficus.
The groups of genera which show general structural resemblance to one another
form a FAMILY. For example, the genera Gossypium, Hibiscus,
Thespesia, Sida, Abutilon and Malva belong to the family Malvaceae.
The families that are similar are grouped into an ORDER. Orders that are
similar are grouped into a CLASS. Classes that are similar are grouped
into a DIVISION. And Divisions that are similar are grouped into
KINGDOM i.e PLANT KINGDOM.
According to this system, plant kingdom is divided into three divisions
namely BRYOPHYTA PTERIDOPHYTA and SPERMATOPHYTA. However,
there is no uniformity in size of categories. Sometimes there are sub-categories
such as sub-division, sub-class, sub-order and sub-family.
Nomenclature
This is concerned with naming of groups and the individuals of a group.
Generally, the plant name has two parts. The first part is the Generic name i.e
Genus to which the plant belongs. The second part is the Specific name i.e
Species to which the plant belongs.
This system is known as Binomial System of Nomenclature. It was first
established by Carolus Linnaeus and later settled by the International Botanical
Congress in 1932.
Attempts have been made to establish a universal name endings for the higher
categories. Class names usually ends in–aceae for example MYXOPHYCEAE.
Family names end in-ae for example, Compositae, Palmae; Orders end in-ales
for example Filicales. Divisions end in – phyta for example Spermatophyta.
There are rules guiding the naming of plants, and this includes:
1.
Generic name starts with a capital letter and specific name starts with
a small letter, example Mangifera indica.
2.
No two plants should have the same botanical name
7
3.
Where plant has more than one name, the first name is the valid.
4.
Names are underlined separately if written or typed
5.
Names are printed in italics
6.
Name of author is abbreviated, and it is found after the name of
Species example Mangifera indica, Linn.
Kingdom protista
This consists of unicellular, eukaryotic organisms such as the protozoa algae ,
like volvox spirogyra etc.
The group algae has the following characteristics:
This group has the following general characteristics
-
Thalloid body not differentiated into root, stem and leave with little
cellular differentiation.
-
Contain green pigment (chlorophyll)
-
Some algae contain other pigments like blue, yellow, red, brown etc in
addition to the chlorophyll.
-
Autotrophic in nutrition
-
Store excess glucose in form of starch
-
Reproduce by fragmentation spore formation or conjugation
-
Cell wall made up of cellulose.
-
Body made up of true parenchymatous cells
-
Some are unicellular, others are multicellular.
-
The multicellular species could be filamentous or colonial
-
They are mainly aquatic and are considered as the most primitive of
plants
-
Example of plants in this group include: Blue green algae (Nostoc,
Anabaena,)
-
Green algae(Volvox,Spirogyra,Cladophora,Chara,Nitella)
-
Yellow green algae (Vaucheria) Diatoms,
8
-
Brown algae (Laminaria,Dictyopta)
Figure 4: Spirogyra
Kingdom Fungi
This kingdom has the following characteristics:
-
They are mainly terrestrial but the lower forms are found wide spread
in aquatic environment.
-
Body is composed of thread like structure called hyphae (collectively
the filamentous fungal body is called MYCELIUM)
-
Body not differentiated into roots, stem and leaves
-
Lack chlorophyll, the colour may be due to pigmentation in cell walls,
cytoplasm or oil globules in the cells.
-
Exhibit heterotrophic mode of nutrition
-
They can be either parasitic or saprophytic but some form symbiotic
association with higher plants (Mycorrhizae) and some form natural
unions with algae (Lichens)
-
Excess sugar stored in form of glycogen
-
Body is made up of pseudoparenchymatous tissues
-
Cell call made of cellulose mixed with chitin.
-
Contain other pigment in cell wall or cell cavity.
9
-
Almost all show an asexual or imperfect spore stage and many
reproduce sexually at a “perfect stage” through true sexual fusion of
gametes.
-
They have a variable life cycle
-
Example slime fungi, Pythium, Albugo, Mucor Rhizopus Yeast
Agaricus, Puccinia.
Diagram of Rhizopus
10
WEEK 2: GENERAL CLASSIFICATION OF THE PLANT KINGDOM
(CONTINUED)
2.0: MAJOR GROUPS OF PLANT KINGDOM
There are different varieties of plants on earth and these plants have been
classified in to three major groups.Viz:
1.
Bryophyta (liverworts & mosses)
2.
Pteridophyta (ferns)
3.
Spermatophyta (seed producing plants)
2.3: Division: Bryophyta
This group has the following general characteristics:
-
Body divided into root, stem and leaf like structures. The root like
structures are called RHIZOIDS
-
Dichotomous branching is common
-
Contain photosynthetic pigment similar to that of higher plants
chlorophyll.
-
Well defined sexual reproduction with clear cut heteromorphic
alternation of generation.
-
Mainly terrestrial, few are aquatic
-
Low degree of tissue differentiation
-
Persisting plant body is the haploid gametophyte, diploid sporophyte
is always wholly or partially dependent on the gametophyte.
-
Spores are always of one kind i.e homosporous.
-
The spores germinate in to a structure called protonema
11
Figure 5: Mosses growing on an old tree trunk.
2.4: Division Pteridophyta
This group has the following general characteristics:
-
Body divided into root, stem and leaf system
-
Have high degree of internal tissue differentiation with conducting
system of xylem and phloem
-
Dichotomous branching is common
-
Growth from apical cell
-
Contain photosynthetic pigments-chlorophyll a and b with caretonoids
-
Clear – cut heteromorphic alternation of generation
-
Spores may be homosporous (Identical) or heterosporous (of two
kinds)
-
Well defined sexual reproduction with antheridia (male gametes) and
Archegonia (Female gametes)
-
Persisting plant body is the Diploid sporophyte which is independent
of the haploid gametophytes
12
-
Mainly terrestrial with few aquatic members
Figure 6: Structure of a frond showing the under side of the leaves
2.5: Division Spermatophyta
This group has the following general characteristics:
-
Body differentiated into root, stem and leaves
-
Dichotomous branching is rear
-
Show highest degree of internal differentiation
-
Growth is from apical meristem
-
Secondary thickening is common
-
Contain photosynthetic pigment-chlorophyll a and b with caretonoids
-
Clearly defined alternation of generation
-
Well defined sexual reproduction and fertilization by means of a
pollen tube
-
Produce seeds which may be borne naked or in a closed structure
(fruit)
-
Mainly terrestrial but with some obviously derived aquatic
representatives, example Cycas, Maize, Rose etc.
13
Figure 7: Showing the structure of Maize plant and its comb
14
WEEK 3 CLASSIFICATION OF ALGAE
The division Phycophyta is divided into the following classes
1.
Class: Myxophyceae or Cynophyceae (Blue-green algae)
Marine, fresh water and wet surfaces no internal cell membranes separating
nuclear materials, chlorophyll, and mitochondria e.t.c. from the cytoplasmic
background i.e. prokaryotic. No flagella storage compounds. Cyanophycin, oil
and glycogen. No sexual reproduction but possibly genetic interchange between
individuals. Asexual reproduction by amitotic cell: fragmentation, non-motile
resting spores a vegetative cells. Commonly algal partners in lichens e.g.
Anabaena, nostoc
Blue pigment (phycocyanin) is present in addition to chlorophyll.
Example, Nostoc, Oscillatoria, Anabaena.
2.
Class: Euglenophyceae: These are simple organism from which evolution
of other plants has started example Euglena.
3.
Class: chlorophyceae (green).
Mostly following, few marine occasionally terrestrial. Unicellular, colonial
filament and expanded thalloid forms food reserve starch cellulose cell wall
Possess green pigment only e.g. Volvox, Spirogyra Chlamydomonas,
Pandorina.
4.
Bacillariophyceae (diatoms).
marine fresh water and any damp surface. Constitute much of the
phytoplankton, free floating and epiphytic, unicellular or in chain or in group of
cells unique wall form in 2 overlapping halves (Petri dish) silicified, sculptured,
eukaryotic food stored as oils and leucosin. Asexual reproduction by cell
divition in which generation became successively smaller
Mostly free-Floating. Boat, rod, disc-shaped.
5.
Phaeophyceae (Brown).
Entirely marine, eukaryotic form range from fixed branched filamentous to
partially organized expanded thallus food reserve are laminarin and mannitol
15
Show alternation of generation
Possess brown pigment (fucoxanthin) example Focus, Laminaria
6.
Rhodophyceae
(red).
Possess
red
pigment-phycoerythrin
example
Polysiphonia, Batrachospernum.
Below are the structural examples of members of the Division Phycophyta
Diatoms
-
-
Mostly are celled algae
-
Posses variety6 of forms
-
Single cells, may form filaments or colonies
-
Found in fresh as well as salt water and in wet grounds
Boat shaped, rod-shaped, disc-shaped wedge-shaped, oval-shaped,
rectangular shaped e.t.c
-
Wall is made up of two halves or valves, an older one called Epitheca
fitting closely over the younger valve called hypotheca (inner valve)
-
The valves are made up of pectin impregnated with silica.
-
They have numerous fine lines which are really very fine dots and
radially symmetrical in the centric and bilaterally symmetrical in elongated
diatoms (Pennales)
In some Genera, there are ingrowths of walls which are called central or polar
nodules according to position. A line called raphae extends from central to the
polar, nodules.
The protoplasm consists of a thin layer of cytoplasm within the cell wall. One
large or many small yellow to golden-brown plastids of varied shapes and sizes,
a central nucleus suspended by cytoplasmic threads or by a broad cytoplasmic
band, and a central vacuole. Gold brawn colour of plastids is due to a pigment
16
called diatomin in addition to chlorophyll. Pyrenoids may or may not be
present. If present, are without the starch envelop.
Reserve foods are globules of fats and insoluble complex substance called
volutin. No starch in diatoms.
Figure 8: Diagram of a Diatom
Spirogyra
-
It is an unbranched filamentous algae
-
It consist of a single row of cylindrical cells joined end to end
-
Each cell is surrounded by a membrane and a cell wall made up of
cellulose and pectin.
-
A thin layer of mucilage covers the cell wall making it slimy to touch
-
The filament is not differentiated into a base and apex.
-
Each cell has a thin layer of cytoplasm in which 2 or more spiral
chloroplast are embedded.
17
-
A nucleus lies in the centre of the cell and is suspended by
cytoplasmic thread.
-
A large vacuole occupies the centre of the cell.
-
On the chloroplast are a number of small nodular protoplasmic bodies
called Pyrenoids and around them minute starch grains are deposited.
Figure 9: Diagram of spirogyra cell.
18
WEEK 4 Classification of Fungi
The division mycophyta is divided water 5 classes.
4.1 Class: Myxomacetes (slime fungi).
-
Grow in damp, shady places in soil such in humus
-
Require moisture and darkness for normal growth
-
Contain pigments like yellow, orange, brown red or colourless
-
Animal like in their vegetative stages and plant like in their reproductive
stages.
Figure 10: Diagram of a club fungi
4.2
Class: Phycomycetes
-
Many are aquatic or damp loving forms, fewer fully terrestrial
-
Mycelium is unseptate and coenocytic
-
Sporangium has many sporangiospores
-
Sexual reproduction is either oogamous or isogamous.
-
Asexual reproduction by zoospores, conidiospores or
sporangiospore
4.3
Cell wall often cellulose food reserve is oil glycogen
Example pythium, phytophtora, mucor, etc
Class: Ascomycetes
19
-
Terrestrial, parasitic or saprophytic
-
Often highly specialized
-
Mycelium is of septate hyphae
-
Protoplast is uninucleated or binucleated
-
Asexual reproduction by non motile spores usually conidiophore
-
Reproductive structure are asci
e.g Sacchromyces, Penicillum, etc
4.4
Basidiomycetes (club fungi)
-
Saprophytes or parasites
-
Often highly specialised
-
Mycelium is of septate hyphae
-
Cells are usually binucleate with haploid nuclei
-
Asexual reproduction by conidiospores
Example Agaricus, puccinia, ustilago
4.5
Deutromycetes (fungi imperfecti)
-
Saprophytes or parasites
-
Reproductive structures are the conidia
-
Have imperfect life-history
e.g fusarium, Helminth osparium
4.6
Morphology of Mucor (saprophyte)
Structure-Mucor grows on animal dung wet shoes, moist bread et.c spreading
like a cobwebs.
Body is composed of white delicate cottony threads called mycelium. The
hyphae are very much branched, but are coenocytic i.e unseptate and having
many nuclei. Only in older parts, and during development of reproductive
structure are there any cross walls formed. As well as ramifying profusely
20
outside the substrate, the fungus sends countless fine branching hyphae in to the
food materials from which it derives its nourishment.
Diagram of Mucor
Pythium (Parasite)
-
Mycelium has hyphae that are long slender, branched, unseptate and
coenocytic.
-
Causes “damping off” disease in crops like tobacco, mustard, ginger,
cress etc under conditions of overcrowd and over watering.
-
Attacks the bases of seedlings feeding on them saprophyticlaly.
-
Facultative parasite.
-
Mycelium of the fungus runs in all direction through the intercellular
spaces and into the living cells of the host (i.e seedling)
21
Week: 5 Classification of Bryophyta
The division bryophyta constitute the non vascular plants and is
divided into 3 classes
5.1 Class Hepaticae (liverworts)
Gametophyte is dorsovetral, prostrate and thalloid in nature
-
Dichotomous branching is common
-
Growth is from apical cell or row of cells
-
Sporophyte is sterile tissue, no chlorophyll and in dependent on the
gametophyte example marchantia, porella, pellia
5.2 Class: Anthocerotae (horned liver wants)
-
Gametophyte is simple and thalloid
-
Sporophyte is complex
-
E.g anthoceros
5.3 Class: Musci (mosses)
-
Gametophyte is erect (in most cases) differentiated into an axis with
leaf like structures above ground.
-
Growth is from a single apical cell
-
Sporophyte show a high degree of differentiation
-
Contains chlorophyll and possess of stomatal aperture
e.g funaria, sphagnum, polytrichum.
5.4
Morphology of Marchantia
-
Plant is thalloid with dichotomous branching
-
Dorsoventral symmetry. Has distinct mid-rib
-
Grows on damp ground or old walls forming a green carpet
22
-
The thallus beans on it ventral side a unicellular rhizoids, a raw of
scales along the midrib, 2 or 3 raws of scales on each side of the
mid-rib with the outer row being close to the margin of the thallus
-
On the dorsal side, there are a number of cup-like outgrowths
called GEMMA cups on the mid-rid.
-
Male
plant
beans
special
reproductive
branches
called
antheridiophores with a disc or receptacle on top
-
Female plant beans the archegoniophores with disc or receptacle on
top.
5.5
Classification of pteridophytes
The division Pteridophyta constitute the vascular plants and is divided in to the
following classes:
5.6 Class: Lycopsida
Members of this class are of world wild distribution with some fossil forms and
a few living forms.
The sporophyte is differentiated in to root stem and leaf but the leaves are
always small in relation to stem size (Microphyllous).
There is no leaf gaps in the stele. There are homosporous and heterosporous
representatives. The sporangia aggregated in to cones or strobila usually at the
ends of branches example Lycopodium, Selaginella.
Diagram of Selaginella
23
5.7 Class Pteropsida
These are also of word wide distribution with many living and fossil forms. The
sporophyte is differentiated in to roots, stem and leaves may be lacking in
mature plants. Leaves always large in relation to stem and spirally arranged.
Leaf gaps in the stele in most cases. They are Homosporous except in one
family (Salviniaceae). Sporangia borne on margins or abaxial faces of leaves,
usually in clusters or sori, except in one group of fossil forms, example
Dryopteris.
5.8 Class Psilotopsida
The sporophyte is rootless and the shoot is composed of branches only or with
small leaves spirally arranged. There is no leaf gaps in the stele. They are
Homosporous and the sporangia is borne singly at the tips of branches. Example
Whisk ferns.
5.9 Class: Psilophytopsida
These class comprises of only fossil order
5.10 Class: Sphenopsida
The sporophyte is differentiated in to roots, stem and leaf. The leaves are nearly
always microphylous and arranged in whorls. There is no leaf gaps in the stem.
The sporangia is Homosporous and borne on distinctive sporangiospores in a
strobilus, example Equisetum.
24
5.11 STRUCTURE OF SELAGINELLA
The saprophyte body is composed of a creeping stem bearing branches more or
less regularly spaced. The stem braches develop at much the same rate as the
main axis, therefore dichotomy appears to be the case. But in reality, the
braches are lateral in development and the branching system is maopodial. The
creeping habit keeps all the stems more or less in a horizontal plane and the
leaves also expand in this plane to form a markedly dorsal ventral arrangement.
The leaves are produced in four rows and are placed in opposite pairs, each pain
having one large and are small leaf. The larger leaves originate from the lower
lateral surface of a stem and the smaller ones from the upper surface. Each leaf
bears a small membranous outgrowth called a ligule which is recognizable in
young leaves but which withers and disappears on ageing.
Slightly behind each fork in the stem, sooner or later a structure resembling a
root develops and grows species, a large tuft of roots may developed at the tip
of the rhizospore.
A mature fertile plant bears vertical branches which differ from the rest of the
stem structure. They are the strobili, bearing sporophylls all of equal size in four
vertical rows. In the axils of the sporophylls, the sporangia are developed.
25
WEEK 6 Classification of spermatophyta
Divided into 3 classes
6.1 Pteridospermae (seed-bearing ferns)
-
Have vegetative characteristics of pteridophytes but bear seed-like
reproductive structure
6.2
-
Farms a link between true ferns and the flavoring plants
-
All are extinct (No longer in existence)
Gymnospermae
-
Mostly trees and shrubs
-
Xylem element always tracheids except one order primitive vessels
are found.
-
Flowers are mostly of strobiloid construction and unisexual
-
Seeds with one integuments and naked
e.g Cycas, pins, Taxus
Figure Scientific classification
Kingdom: Plantae
Divisions Pinophyta (or Coniferophyta) - Conifers
Ginkgophyta - Ginkgo
Cycadophyta - Cycads
Gnetophyta - Gnetum, Ephedra, Welwitschia
26
Figure: Coast Douglas-fir cone
Angiospermae
-
World’s dominant vegetation in all habitats
-
Adopted to life on land
-
Posses true xylem vessels
-
Flower consisting of works of sterile and fertile parts.
-
Flowers usually hermaphrodite
-
Male gametophyte represented by pollen grain, female by embryosac with of nuclei
-
Endosperm formed as a result of triple fusion
-
Seed has two integuments enclosed in specialized cupels called
ovary which ripens into a true fruits.
27
Classes of Gymnosperms.
Gymnospermae are divided in to three classes, these are:
Class: Cycadopsida, example Cycas
Class: Coniferopsida example Pinus, Ginkgo
Class: Gnetopsida example Gnetum, Ephedra
6.6 Classes of Angiospermae
6.6.1 Sub-class marocotyledam
-
Mostly herbaceous, few palm but no tree
-
Adventitious root system
-
Usually parallel veined leaves
-
Vascular bundles irregularly arranged in the stem.
-
Secondary growth is rare
-
Flaver parts are in threes or multiple of threes
-
Single cotyledon in the seal
-
E.g maize wheat
6.6.2 Sub – Class Dicotyledons
-
Mostly herbs, shrubs and trees
-
Tap root system
-
Vert-veined leaves
28
-
Vascular bundles arranged in rings in the stem
-
Secondary growth is usual
-
Floral parts are in fours or fives (45/55) or multiple of these.
-
Two cotyledons in the seed (reely one by reduction).
3.7
The structure of a gymnosperm pinus plant
It is a tall, erect, evergreen trees
-
can grow up to a height of 45 metres.
-
Has well developed tap-root and numerous aerial branches with needlelike leaves
-
Stem is rugged and covered with scale bark
-
The branches are of two kinds:
1
Long branches (of unlimited growth) in apparent wherls developing from
lateral buds and
2
Dry branches (of limited growth).
-
1
Leaves are also of two kinds:-
Long, green, needle-like foliage leaves, called needle borne only on dway
branches (foliar spurs) and
2.
Small, brawn, scaly leaves borne on both kinds of branches. The number
of needles (leaves) in a cluster varies from 1 to 5 depending on the species
Diagram.
Structure of Angiosperms
-
Range in size from minute forms e.g Wolffia to ginat trees
-
Flaver, plants as the higher seed plant
-
Ovule matures into a seed and is produced within the space enclosed
by a carpet thus are sand to produce enclosed seeds
-
Matured ovary or fruit exhibit a wide variety of forms. May be simple
or compound fruits, dry or flashy fruit
-
Leaves are megaphylls, large and broad
29
6.4 Differences between gymnosperms and Angiosperms
Gymnosperms
Angiosperms
1
Xylem exclusively made tradechied
Xylem mainly composed of resin
2
Phloem contain no companion cells
Phloem contain companion cells
3
Flavers are simple no calyx no corolla
Flavers are complex
4
Flowers always unisexual
Flavers unisexual bisexual
5
Air-current is the only pollinating There are many different pollinating
agent
6
agents
Ovules are freely exposed on the Ovules remain enclosed in the ovary.
megasporohyll (carpel)
7
During pollination, pollen grain enter Pollen grain are deposited on the
the micropyle and are lodged on the stigma
nucleus
8
Male gametophyte presented by a few Male gametophyte reduced to 2
cells usually 2 or 3 a vestigial nuclei only i.e tube nucleus and
protahllus
9
Female
generator nucleus
gametophyte
is
a
large Female gametophyte is represented
structure with archegonia embedded in by an 8-nucleate embryo – sac and
it, each with on ovum
the ovum is free in it without any
archegonia.
10 Endosperm formed from vegetative Endosperm is formed from definitive
tissue of female prothallus before nucleus only after fertilization and is
fertilization and is haploid (n)
triploid (3n) cotyledons are 1 or 2.
30
WEEK 7 Common flowering plant families some monocotyledonous plant
families
7.0 Characteristics of the family gramineae (poaceae)
Habit – Herbs, rarely woody (bamboos)
Stem – Cylindrical with distinct nodes and internodes sometimes hallow
Leaves – Simple, alternate, with sheathing leaf-base split on the side opposite
leaf-blade
Flavers- Usually bisexual, sometimes unisexual monoecious.
Perianth – Represent by two or three minute scales (lodicules)
Androecium – Stamens three, sometimes to, anthers versatile and pendulous
Gynoecium – Carpe (3), reduced to one (according to same authors) by fusion
or suppression of two, ovary superior, one – celled, with ovule, styles two (but
three in baboos, and two fused into one in maize), rarely terminal or lateral
stigmas feallery
Fruit – caryopsis. Pollination by wind. e.g Grass, Bamboo.
Family – Palmae
Habit – Shrubs or tree, sometimes climbing
Stem- Erect, unbranched and woody. Has scars or shed leaves. Height 45m
above
Roots – Numerous, fibre developing from base of stem.
Leaves – Usually forming a crown, petiole with stout sheathing base.
Flowers – sessile, small and inconspicuous but produced in large numbers
(12,000 indicate palm regular, hypogenous, unisexual (rarely bisexual), male an
female flowers in some inflorescence or in the either monoecious or dioecious.
Perianth – in two whorls, 3 + 3 the outer being smaller, usually free, persistent
in the female flower
Androecium – stamens usually in two whorls 3 + 3 filaments free or connate
anthers versatile and two celled
Gynoecium carpels (3) OR three ovary superior, unilocular aartiloculer with one
or three ovules
31
Fruit – drupe, berry or nut. Pollination by wind, sometimes insects
Floral formulae
7.1 Family Liliaceae
Habit – herbs, climbers, rarely shrubs and trees with a bulb or rhizome or with
fibrous roots
Leaves – are simple, radical or cauline or both (radical = cluster of leaves
arising from short underground stem an it from the roots cauline = directly
borne by the aerial parts of the stem and branches)
Flowers – regular, bisexual (rarely unisexual, dionegroud three – mercus and
hypogenous, bracts usually small, scarious (thin, dry and membranous)
Perianth – Petals are petaloid, usually 6 in 2 whorls 3 + 3 free or (3 + 3) united
(i.e polyphyllous and gamohylous respectively)
Androecium – stamens are 6 in 2 whorls, 3 + 3 rarely 3, free or united with
perianth at the base (epiphyllous), anthers often dorsifixed
Gynoecium – carpels (3) syncarpous, ovary superior, ovules usually ∝ (infinite)
in two rous, placentation axile, styles (3) or 3.
Fruit – a berry or capsule.
7.2 Dicotyledonous Plants
7.2.1 Characteristics of some dicotyledonous Families
7.2.2 Family Leguminosae
Habit: Herbs, shrubs, trees, twiners, climbers
Leaves: Alternate, Pinnately Compound, rarely simple, stipules 2, usually free
Flower: Bisexual and complete, regular or irregular (actinomorphic or
Zygomorphic) hypogenous or slightly perigynous
Calyx: Sepals usually five with the cold one anterior (i.e away from the axis
sometimes (4) .
Carolla: Petals usually five, with the odd one posterin
32
Androecium: Stamens usually ten or numerous, sometimes less than 10 by
reduction, free or united
Gynoecium: Carpel one, ovary one-celled with one to many ovules, superior,
placentation marginal
Fruit: commonly a legume or pod (dehiscent), sometimes lomentum (in
dehiscent)
The family is large and is divided into three – subfamilies
Subfamilies
Caesalpinioideae
Mimosoideae
Faboideae
Scientific classification
Kingdom: Plantae
Division Magnoliophyta:
Class: Magnoliopsida
Order: Fabales
Family: Fabaceae
33
Diagram of the fruit of Gymnocladus dioicus (1),and a flower of Wisteria
sinensis, Faboideae. Two petals have been removed to show stamens and pistil
(2)
1
2
Diagram of Legume of Vicia angustifolia (1) and Pisum sativum (2)
1
2
34
7.2.3 Family: Malvaceae
Habit: Herbs shrubs, trees
Leaves: simple, alternate and palmately viewed
Flowers: Irregular, Polypetalous, bisexual, hypogenous, copiously mucilaginous
with a whorl of epicalyx
Calyx: Sepals (5), valvete
Carolla- petals 5, attached to the base of staminal tube
Androecium: Stamens numerous, monadelphous (united into one bundle =
staminal column/tube), epipetalous (staminal tube adnate to the petals at the
base) anthers reinform, unilocular, pollen grains large and spiny.
Gynoecium: Carpels commonly (5 to α), ovary superior, 5 to α - loculus
placentation axile, style passes through staminal tube, stigma is free as many as
the carpels
Fruit: Capsule or schizocarp
Seed: Endospermic
7.2.3 Family: Compositae e.g Tridax
Habit: Herbs and shrubs, rarely twiner or tree
Leaves: Simple, alternate or opposite, rarely compound.
Flowers: (or flared) are of two kinds. Central ones called disc florets. They are
tubular and the marginal ones called ray florets. They are ligulate sometimes all
florets ar of the same kind (tubuler or ligulate)
35
Disk Floret: Regular, bisexual, epigenous
Calyx:- Modified into hairs= pappus or into scales or absent
Corolla:- Petals (5) tubular
Androecium: Stamens 5, epipetalous (attached to petals by their filament)
syngynesions (anthers united but filaments free).
Gynoecium: Carpels (2), ovary interior, 1 – celled with one basal, anatropous
ovule, style 1, stigma bifid,
Fruit:- crypsela
Ray floret: Zygomorphic, unisexual or sometimes neuter (e.g sunflower) and
epigenous.
Calyx: Modified into pappus, scale or absent
Carolla: Petals (5), gamopetalous, ligulate (strap – shaped)
Gynoecium: as in disc florets
36
WEEK 8: Family Bambacaceae
8.0 Characteristics:
This family has the following characteristics:
• Habit: These are large trees
• Leaves: These are simple or digitately compound with deciduous stipules
• Flowers: The flowers are regular, large, bisexual and hypogynous.
• Calyx: This is gamosepalous with (5) sepals. It is valvate, often with an
epicalyx.
• Corolla: This is polypetalous with 5 petals and imbricate
• Androecium: These are 5-∞ stamens, free or polyadelphos.The anthers are
two celled sometimes more. The pollen grains are smooth and staminodes
are often present
• Gynoecium: This is syncarpous, with (2-5) carpels. When 5, the carpels are
opposite to the petals.
• The ovary is superior, multilocular with 2 -∞ - ovules in each loculus.
• Fruit: The fruit is capsule
• Seeds: These
are small, often very heavy and with scanty or no
endosperm.
• Eg Bambax, red or silk cotton tree, Bambax ceiba
Family Rutaceae (citrus)
• Habit: These are shrubs and trees
• Leaves: The leaves are simple or compound, alternate or rarely opposite
and gland dotted
• Flowers: These are regular hypogenous and bisexual. The disc below the
ovary is prominent and ring or cap like.
• Calyx: There are four or five sepals free or connate below and imbricate.
• Corolla: petals four or five free imbricate
37
• Androecium: The number of stamens varies. They can be as many or more
often twice as many as the petals or numerous as in citrus. They are free
or united in irregular bundles and inserted on the disc.
• Gynoecium: These are generally (4) or (5) carpels or ∞, as in citrus. They
are syncarpous or free at the base or united and either or seated on a disc.
The ovary is generally four or five locular or multilocular as in citrus,
with axile placentation. There are usually two ovules in each loculus
arranged in two rows.
• Fruit: This is a berry, capsule or hesperidium.
• Seed: The seeds may or may not have an endosperm. Polyembryony is frequent in citrus Eg lemon , citron, lime, orange and pummelo.
Diagram of a Citrus plant. (Citrus reticulata cultivar)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
38
(unranked): Eudicots
(unranked): Rosids
Order: Sapindales
Family: Rutaceae
Subfamily: Aurantioideae
Tribe: Citreae
Genus: Citrus
8.2 family meliaceae
• Habit: These are mostly trees rarely shrubs.
• Leaves: The leaves are pinnately compound and the leaflets are oblique.
• Inflorescence: This has an axillary panicle
• Flowers: These are regular, often bisexual sometimes polygamous and
hypogynous.
• Calyx: There are (4-5)sepals (gamosepalous)
• Corolla: There are 4-5 petals(usually polypetalous)imbricate
• Androecium: There are 8-10 stamens, generally united in to a long or short
staminal tube.
• Gynoecium: There are (2-5) carpels(syncarpous)the ovary is superior, it is
2-to5-locular,rarely unilocular, with one or two ovules in each chamber.
disc is annular surrounding the ovary.
• Fruit: The fruit is a capsule, berry or drupe.
• Seed: This is often winged, and albuminous eg Mahogany, satin wood.
8.3 Family anacardiaceae
• Habit: These are shrubs or trees. Many of them are resinous.
• Leaves: These are simple or pinnately compound alternate and exstipulate.
• Inflorescence: This is a panicle of many small flowers .
39
• Flowers: The flowers are small, regular and bisexual they are sometimes
polygamous, hypogynous to epigynous and usually pentamerous. The
disc is present.
• Calyx: There are usually 5 sepals, though they vary from 3-7.they may be
free or united.
• Corolla: There are as many petals as sepals. The corolla is sometimes
absent. it may be free or connate.
• Androecium: There are 10-15 stamens (the number of fertile stamens
varies in many cases. They are free and inserted on an annular disc .
• Gynoecium: These are usually (3-1) carpels and rarely 5 (syncarpous).The
ovary is superior or some times inferior .it is often 1-celled (rarely 2-5
celled)and has one ovule in each chamber .often only one ovule matures
in to a seed.
• Seed: The seed is exalbumenous with a large curved embryo. Eg mango,
cashew tree.
Anacardium occidentale, cashew
40
Mangifera indica, mango
8.4 Family Sterculiaceae
• Habit: These are shrubs or trees rarely herbs.
• Leaves: leaves and stipules are like those of Malvaceae.
• Flowers: The flowers are often regular and zygomorphic. They are
bisexual, rarely unisexual and hypogynous.
• Calyx and corolla: These are like those of malvaceae, sometimes corolla
is absent. There is no epicalyx.
• Androecium: The number of stamen varies from 5-25 though they are
usually ∞ stamens. They are mostly arranged in two whorls the outer
whorls opposite to d sepal and often reduced to staminodes or absent and
the inner whorl opposite to the petals, being fertile and often branched all
stamens is more or less united below into a tube or sometimes on the
gonophore. The anthers are 2 locular.
• Gynoecium: There are (5-2) carpel (often 5),syncarpous. The ovary is
superior and in 5- to 2- locular, with 2- anatropous ovules in each loculus.
The style is simple and the stigma lobed.
• Fruit: The fruit can be dry or fleshy and is often a schizocarp.
• Seed: This has a fleshy endosperm, sometimes arillate, example cola,
cocoa tree.
41
WEEK 9 Technique for collecting and preserving common flora
(HERBARIUM)
Herbarium is a collection of dried, pressed, nicely preserved plant specimens
arranged in sequence of an accepted system of classification. It is used for
identification of fresh specimens, comparison between floras of different
regions.
The value of a herbarium depends on the care with which specimens were
preserved and mounted, accuracy and completeness of identification and
labeling and maintenance so that they do not deteriorate and can easily be
referred to.
Equipment for collection and collecting methods.
1.
Specimens that have both flowers and fruits are selected.
2.
Digger / trowel – for digging out the underground parts of the plants
example Rhizome, corm, tubers etc. These parts help in identification
and classification of the plant.
3.
Pruning knife/bent sickle:- These have to be sharp. Pruning knife is
used for cutting branches of herbs, shrubs and trees. Bent sickle has a
long handle and is used for collecting flowers/fruits from high trees.
4.
Vasculum/plastic bags:- Vasculum is an oval metallic container with
screwed fasteners to keep it airtight to avoid wilting. Plastic bags can
also be sued as they prevent loss of moisture when close tightly.
5.
Field note Book:- This is a pocket sized note book used to record all
information concerning the plant: These include
a. Location e.g. country, province, Stale Park, river. Etc
b. Habitat example river bank, forest edge, open field, swamp etc
c. Field observation of the plant example height flower, colour, fruit
colour, odour.
d. Nature of stem juice example milky colour sticky, red, clear sap,
thick, watery
e. Collection number example 1 . . . . . followed by your last name
42
f. Date of collection
g. Name of plant if know name could be local, common or botanical
h. Association with other plants and its abundance.
9.1 Plant Press
This consists of equal sized top and bottom frames measuring 30cm x 45cm
made of these, light, strong pieces of plywood or metal. Between the frames are
the folders, blotters and ventilators. Folders are old newspapers in which the
collector places the specimens. Blotters absorb moisture from the specimens
while ventilators provide air for drying. The press is tightly bound together by
strong straps of canvas or leather and is placed in the hot sun or suspended over
moderate heat.
9.2 Plant Pressing
Plants for pressing should be placed in the folders in a manner so as to give
maximum possible natural look. Longer specimens are bent into a V or W shape
so as to fit them on a standard sized mounting sheet (30 x 45cm). Leaves,
flowers parts should not be crouded. Thick organs may be trimmed and cotton
paid placed proper pressing.
9.3 Mounting of pressed specimens:
The pressed, dried specimen are glued or gummed to a hard standard sheet of
paper. The paper should be fairly heavy to reduce. Flexing when mounted
specimen are picked up.
9.4 Label
Label is an important part of finished but usually 6 x 10cm. they are pasted with
glue on the lower right hand corner of the mounting sheet. A label should
contain the following information’s.
43
1. Region of collection accompanied by name of the institution.
2. Botanical name of the plant with the author citation
3. Locality of the collection
4. The habitat
5. Name of the collector and his field number
6. Collector field observation
7. Date of collection and the name of the person who identified the
specimen.
9.5 Filling
This is the arrangement of specimens in a herbarium. Specimen are filed
according to a particular system of plant classification filling is done
alphabetically for genera or according to phylogenetic sequence (in major
herbaria). Specimens belonging to are genus are placed within a genus cover. In
many major herbaria, the scheme of technicolour folder is in usage. The colour
of the folder is indicative of the distribution of the plant.
9.6 Care of specimens
Herbaria in warm and moist regions appear to face pest problems. The common
pest adults and larvae of tobacco beetle (Lasioderma serricorne) and drug store
beetle (Stegobium paniceus).
These are controlled in the following ways:
1.
Use of insecticides example Dichlorodiphenyl) trichloroethane (DDT),
carbon disulphide and cyanide gas.
2.
Specimens are poisoned with 10% aqueous solution of mercuric
chloride
44
3.
Use of insect repellants example Naphthalene balls and Para
dichlorobenzene mixed in the ratio 2:1 and put in herbarium case.
4.
Use of calcium chloride in small bottles the mouth covered with lose
cotton and kept in herbarium cases to absorb moisture thereby
preventing fungal attacks.
5.
Specimen should be handled with care to avoid cracking and
crumbing, tear and wear
6.
Store specimens in steel cabinets and fire – proof buildings
9.7 Uses of Herbarium
1.
The vegetation in any particular region is easily known.
2.
While exploring a new area, the herbaria of previously explored areas
can be referred to
3.
Data about the nature, distribution and ecology of any plant of
economic or medicinal value can be obtained easily.
4.
It can serve as the basis for other branches of botany example plant
ecology. Phytogeography, Economic botany e.t.c
45
WEEK 10 General classification of the Animal Kingdom
Members are all multicellular and exist either in water or on land. The animal
kingdom is divided into two major groups
Group – invertebrata and
Group – vertebrata.
The invertebrates comprises of animals that do not passes backbone while the
vertebrate animals are those that posses backbone
The group invertebrate comprises of the following phyla:
Phylum: coelenterata
Phylum: Platyhelminthes
Phylum: Nematoda
Phylum: Annelida
Phylum: Arthropoda
Phylum: Mollusca
10.1 Group – Craniata (vertebrata)
This forms the major part of the phylum chordata
General Characteristics of vertebrata
-
Possession of an enlarged brain that is enclosed in a brain case – cranium
-
A segmental spinal column of vertebrae that became the axial support of
the body
-
Body comprises of a head, neck, trunk and tail
-
Show a progressive series of structural and functional advances in all
organ systems.
Other characteristics include
46
1.
Body covering is a stratified epithelium of epidermis and dermis with
many mucous glands in aquatic animals.
Most fishes are covered with protective scales in land dwellers, the
exterior is confined with scales on reptiles, features on birds and hair on
mammals.
2.
The internal and jointed skeleton is of cartilage in lower vertebrates and
of bane in higher groups. This support and protects various organs
3.
Muscles are attached to the skeleton that makes movement possible
4.
Complete digestive tract that is ventral to the vertebral column
5.
Circulatory system of a well developed muscular heart of two, three or
four chambers
6.
Respiration in lower forms is by paired gills while terrestrial forms have
lungs
7.
Paired excretory organism – kidney. In lower form, it is segmental in
nature and drain waste both from the coelom and the blood. In higher
forms, it is non segmental and drain only from the blood.
8.
Series of endocrine glands that secrete hormones for regulation of body
processes.
9.
With rare exceptions, sexes are separate
The group vertebrata comprises of the phylum chordata with the following
major classes
Pisces (Fish), Amphibian (Amphibians)
Reptilia (Reptiles), Aves (Birds) and Mammalia (mammals)
47
10.2 Group invertebrata
Phylum Cnidaria
Characteristics of the phylum: Cnidaria or coelenterata
-
Tissue grade of organization
-
Simple aquatic animals, mostly marine with few fresh water forms
example Hydra.
-
Radially or biradially symmetrical with a central gastrovasculer cavity
that opens to the exterior as the mouth
-
Only one opening i.e mouth with no anus
-
Diploblastic, outer layer called ectoderm and an inner layer of
endoderm separated by a non cellular, gelatinous mass called
MESOGLOEA.
-
Fairly small animals but often fund joined together to form colonies,
units being termed Z00IDS
-
Possess nematocyst used for paralyzing prey or holding it.
-
Mouth surrounded by tentacles
-
No circulatory, respiratory or excretory organs.
-
No coelomic cavity
-
Nerve system of one or more net work of nerve cells but no central
nervous system
-
Exhibit polymorphism i.e two main types of structures, the polyp and
MEDUSA. Polyp is sessile and is the asexual form of zooid while
medusa is free swimming and is the sexual zooid
-
Reproduction is both asexual and sexual. Asexual is by budding and
sexual occurs by means of sperm and ova.
-
Egg usually develops into a ciliated free swimming larva known as
PLANULA e.g Hydra, obelia, physalia, jellyfish and sea animal
This phylum consists of three main classes
48
Class: Hydrozoa
-
Solitary or colonial
-
Asexual polyp and sexual medusae present medusae with a velum.
Freshwater from include Hydra. Marine mostly e.g obelia, physalia
Class: Scyphozoa
-
Solitary
-
Polyp stage reduced or absent
-
Bell shaped medusa without a velum
-
All are marine.
e.g Jellyfish (Aurelia aurita).
Class: Anthozoa
-
Solitary or colonial
-
Exclusively marine forms
-
All polyps, no medusoid stage
-
Found attached to stones, seaweed or should e.g sea anemone (Tealia
crassicornis)
Corals (Meandrina Cerebriformis)
-
Small solitary polyp living in fresh water size is 10 – 30mm.
Body is cylindrical tube with lower and classes to form based disc or fort
used for attaching objects and locomotion.
The opposite and free oral end contain mouth on a conical hypostome encircled
by 6 – 10 slender tentacles.
Mouth leads into a digestive cavity or gastrovasculer cavity or interact.
Nematocysts are found throughout the epidermis especially on the tentacles.
49
The side of the body may bear lateral buds that give rise to new individual by
asexual reproduction. At times, it beers other rounded projections, the ovaries or
tests concerned with sexual reproduction
10.3 Phylum Platyhelminthes (flat worms)
General characteristics
-
Bilaterally symmetrical.
-
Dorsoventraly compressed (flattened).
-
Non segmented worms
-
Acoelomate, triploblastic animals
-
A system of flame cells and excretory vessels is present
-
No blood vascular system.
-
Hermaphrodite
-
Many are free-living but others are parasitic on or in the bodies of
larger animals
-
Single opening to the alimentary canal i.e the mouth
-
Great power of regeneration
There are three main classes.
Class: Turbellaria –entirely free living
Class: Trematoda (entirely parasitic)
Class: cestoda (entirely parasitic)
Example: planaria, fasciola, taenia, schistosoma
External features of Planaria
These are small creatures with flattened leaf-like bodies.
Black in colour, up to 15mm long.
Body is broad in front than at the back
Where it roundly tapered and became extremely flattened. Has a definite front
end, upper dorsal surface and lower ventral surface which is applied to the
50
substratum. Eyes are found near the anterior end. Mouth is at the ventral surface
and of the only opening to the gut.
10.4 External features of Fasciola hepatica
Diagram
Leaf like structure. Adult has a flattened, oval shaped structure 2.5cm long and
1.2 – 1.3cm wide.
Anterior region has a triangular projection at the apex – main and is surrounded
by oral sucker. Ventrally at the base of the projection is a rounded ventral
sucker. Between the two suckers is a shallow depression genital atrium.
Posteriorly is a minute, terminal excretory pore.
Body is covered by a tough cuticle. Mouth leads into a short buccal cavity
followed by muscular pharynx and a narrow oesophagus which fork into two
blind branches leading to posterior region and given off numerous lobed caeca.
10.5 Phylum Nematoda (Round Worms)
-
Bilaterally symmetrical, Triploblastic
-
Unsegmented, pseudocoelomates
-
Cylindrical but tapering at the anterior and posterior ends.
-
Uniform in structure although differ in size and habitat.
-
Can be found in terrestrial, freshwater, marine or parasitic habitats.
-
Lack suckers mouth is surrounded by Lips or papillae
-
All are dioecious (separate sexes
-
Alimentary cannot is a straight complete tube with two openings,
mouth and anus.
-
Species parasitic in man vary in size from threadlike object just visible
to the naked eye (sronglyloides) to elongated string-like worms
attaining a length of 60cm (Dracunculus)
-
Have internal fertilization,
-
Females are either viviparous (produce larva) or oviparous (lay eggs).
51
-
Moult usually four moult during development from ovum to adult and
third stage larva is responsible for infection of a new host.
-
Nematodes which infect human live in the tissues or intestinal tract.
Tissue nematodes are transmitted by insect vector only while intestinal
nematodes are soil transmitted
Nematodes are divided into two main groups based on phasmids (caudal
sensory structure)
1.
Class:- Aphasmida
Members lack phasmids. Male has one spicules example, Trichuris
trichiura (whipworm) in soil, Trichinella spiralis (fund in undercooked or raw
meat,
2.
Class: Phasmids: Members have phasmids, male has two spicules
example,
Ancylostoma
duodenale
(hookworm)
Dracunculus
medinensis (Guinea worm) Ascaris Lumbricoides) (roundworm
Structure of T. Spiralis
Small cylindrical worm pointed anteriorly and rounded posteriorly, female is
3mm long and 80cm wide, male is 1.5mm long and 40.cm wide
Structure of Ascaris lumbricoides
-
Large worm, body is relatively stout although it tapers at each end
particularly at the hinder end.
In male, the tail end curves sharply towards the ventral surface, shows a pair
of blister (copulatory spicules) protruding from the cloaca which is situated a
centimeter from the tip of the tail.
Three lips guard the entrance of the mouth. Body is encased in a tough but
smooth cuticle which is semitransparent so that some of the internal organs
are seen through it.
52
10.6 Phylum Annelida (Ringed Animals)
General Characteristics
-
Triploblastic, elongated cylindrical body
-
True segmented worms
-
Metameric segmentation
-
Perivisceral coelom is present.
-
Body wall very muscular and have an inner layer of an outer layer of
circular muscles
-
Nervous system well developed
-
Excretory system consist of tubes called nephredia
-
Body covered by thin cuticle with setae
-
Some live in sea, soil or parasitic
-
Closed blood system, digestion is extra cellular
-
Larva when present is trochophore e.g earthworm, leeches, and nereis.
There are three main classes
Class: Polychaeta
-
Largest class of annelids
-
Mostly marine with few found in brackish water, freshwater and moist
soil.
-
Same free living, same tube living and same burrows into mud.
-
Have well marked internal and external segmentation
-
Each body segment bears a pair of appendages called parapodia which
bears numerous chaetae
-
Many reach up to a length of 1m.
-
Cephalisation is well pronounced.
-
Well defined head region with eye and tentacles
53
-
Parapodium used for locomotion assisted by chaetae
-
Sexes separate No permanent gonads
-
Fertilisation is external with a free swimming trochophore larva,
Example Nereis diversicolar (rag worm)
Arenicola (Lugworm)
Chaetopterus (tube living worm)
Diagram of Nereis
Class: Oligochaeta
-
Terrestrial or freshwater habitat.
-
Well marked external and internal segmentation
-
Posses few chaetae e. No parapodium
-
Hermaphrodite, cross fertilization
-
Clitellum present at sexual maturity
-
Eggs are deposited in cocoon.
-
No free larval stage
-
Respiration over the entire body surface example earthworm, tubifex
Diagram of Earthworm
54
Class: Hirudinea
-
Vermiform, dorsoventraly flattened
-
Body consist of definite number of segment marked externally by
secondary rings and annuli
-
Capable of elongation and contraction to different proportion
-
Feed by sucking in organic matter using pharynx or may be parasitic
by sucking blood of mammals, frog/tadpoles and small fishes
-
Found in ponds, swamps and slow flowing streams
-
Hermaphrodite
-
Lack setae and parapodium.
example Hirudo medicinalis
Diagram of Hirudo medicinalis
10.7 phylum: Arthropoda (Jointed limbs)
In terms of number of species and individuals, this phylum surpass any other
phylum. Of some 1 ¼ million known animal species, 4/5 are arthropods. Also
this phylum contain the class insecta which represent almost ¾ of described
animal species.
General Characteristics of this Phylum
•
Triploblastic
•
Bilaterally symmetrical
•
Metamerically segmented
•
Paired jointed appendages on each metamere with at least one pair acting
as a set of jaws.
•
Reduced coelomic cavities and a major body cavity – Haemocoel with
fluid called Haemolymph.
•
Presence of a skeletal covering composed of chitin. This forms the
exoskeleton.
55
•
Nervous system with cerebral ganglionic mass connected to ventral
paired ganglia
•
Open circulation with no blood vessels
•
Anterior photoreceptors
•
Moult and metamorphosed between immature and adult stage during
growth
•
Sexes separate
•
Can be found almost in every environment including aerial one
Classification
There is no definite system of classification for the phylum existing in view of
divergent ideas concerning the phylogeny of arthropods. It is in a state of flux
and may always remain.
Divided into four subphyla
1.
Subphylum –
Trilobita (extinct)
2.
Subphylum –
Chelicerata consisting of the class: Arachnida,
Merostomate and Pycnogonida
3.
Subphylum –
Crustacean
4.
Subphylum –
Uniramia consisting of the classes
Insecta
Myriapoda
Chilopoda
Symphyla
Diplopoda
Pauropoda
56
Subphylum – Chelicerata
Absence of antenna, presence of a pair of chelate appendages as the first pair of
segmental appendages
Class – Merostomata
Characteristics
•
Aquatic, usually marine with brachial respiration
•
Body divided into two – prosoma and opisthosoma
Prosoma has chelicerae on the first segment and 5 similar pairs of appendages
on the 2nd – 6th segments.
The opisthosoma is divided into a Mesosoma with 5 or 6 pairs of lamilli form
appendages of which the 1st form a genital operculum while others are biramous
and bears gills and a Metasoma without appendages and with a telson. E.g.
Horseshoe crab
Class: Arachnida
e.g. – spiders, scorpion, harvest man
General Characteristics
•
Body divided into two parts anterior prosoma (cephalothorax) bearing six
pair bears the chelicerae that is associated with the mouth (pre oral)
second pairs bears the pedipalps (post oral). The remaining four pairs are
legs. Posterior opisthosoma makes up the abdomen. The genital opening
is on the anterior part of the opisthosoma. The only appendages here are
the pectines of scorpions and spinnerets of spiders
•
Respiration is by lung books and or tracheae.
•
Development is straight forward without metamorphosis
57
•
Generally terrestrial
Subphylum – Crustacean
e.g. crabs, shrimps, lobsters, woodlice
Characteristics
•
Aquatic with majority occurring in marine environment
•
Exhibit tremendous morphological diversity
•
Include the largest arthropods, the crabs and lobsters as well as the
smallest tiny water fleas and shrimps.
•
Five of the six head segments bears appendages
•
Two pairs of sensory antennae and three pairs of mouth parts
•
The remaining segment is divided into two region, thorax and abdomen
terminated by a post segment region telson
•
The thoracic segment fused with head to form the cephalothorax while a
backward fold of head forms the carapace
•
Sexes are separate and often display sexual dimorphism but few are
hermaphrodite
•
Reproduction is by sexual means but parthenogenesis also occur
•
Very plentiful is sea therefore termed marine insects.
Subphylum – Uniramia
Class – insecta
e.g. grasshopper, cockroach, ant, fly
General characteristics
•
Most extensive class in the animal kingdom
•
The number of described species exceeds the number of all other known
animal species
•
Invade all habitable terrestrial environment
•
Body divided into three regions – head, thorax and abdomen
58
•
Head bears six segments, a pair of antenna, three pairs of mouth parts,
mandibles, first and second maxillae
•
Thorax bears three segments and each segment bears a pair of
appendages (legs), second and third segments bears wings if present
•
Abdomen bears eleven segment and posterior telson
•
Anus opens at the posterior end of the abdomen and just anterior to it are
the genital aperture that opens ventrally
•
Appendage at the eleventh segment is the Cerci
•
Respiration by direct diffusion of gases
•
Undergo metamorphosis during development
•
Depending on feeding habit, mouth part can be modified into sucking,
piercing or chewing type.
Class: Myriapoda
Characteristics
•
Body consist of head followed by numerous similar segments
•
Series of similar legs bearing segment
•
Single pair of antennal
•
One or two pairs of maxillae behind mandibles
•
Mostly terrestrial
•
Include the centipedes and millipedes
10.9 Phylum: Mollusca
General Characteristics
Second only to arthropods in terms of abundance
-
Display a belvildening diversity in form despite sanitarily in basic
morphology
-
Range in size from minute of few mm (half mm) snails to giant squids
which is over 15m long exclusive of tentacles that is 6m in circumference
59
and weighing 2 – 3 tonnes. Includes the small flattened chitins which
creep about on rocks of sea share, staggering variety of bivalves, snails
slugs and peculiar borrowing tooth shell of sandy of muddy substratum.
The most highly evolved are the predatory cephalopods (Octopus, squids
and cuttlefish).
-
Wide spread in aquatic and terrestrial habitat.
-
Triploblastic
-
Coelomate animals which do not show segmentation, soft bodied and
bilaterally symmetrical
-
Body consist of head, with tentacles flat creeping foot and dame like
visceral hump containing most of the alimentary canal, digestive gland,
gonads, heart, kidney and paired gills called ctenidia.
The skin of the visceral hump is called the mantle which grows downward
posteriorly to cover a cavity called mantle cavity into which opens the anus,
the excretory and reproductive duct. The mantle secretes the shell.
-
Sometimes a larval form which resembles the trochophore larva of
annelids
-
Of interest to man as food, as source of dyes, intermediate host to
many important parasitic helminthes, destructive barer and producers
of pearls, shells use extensively for bolluns ornament, for shell
collection
-
Moth is interiorly while anus is posteriorly located
Six main classes
1.
Class:
Monoplacophora
2.
Class:
Amphineura
3.
Class:
Scaphopoda
4.
Class:
Gastropoda
60
5.
Class:
Bivalvia or lamellibranchiata
6.
Class:
Cephalopoda
Class: Monoplacophora – mainly fossil molluscs
Only one living genus neopilina with four known species. Have limpet – like
appearance lives in the depth of the ocean. Shell of neopilina is uncoiled. There
is a simple foot used for creeping. Gills, kidneys, coelomic sacs and contain
muscles are serially repeated.
Class: Amphineura
Constitute a small class of marine mollusks
Represented by several genera and species of chitins, all of which hare small,
sluggish creatures found in rock crevices or clinging to the undersides of stones.
Possess a dorsal shell made up of longitudinal raw of eight plates. The head foot
has a broad creeping sole but the head – foot has a broad creeping sole but the
head is inconspicuous and devoid of tentacles or eyes. The mouth is at the
anterior end of the head and the anus at the extreme posterior end of the body.
Bilaterally symmetrical.
Class: Scaphopoda
These are small group of burrowing marine mollusks known as the tusk – shells
with a hollow that opens at both ends within which is an elongated body with a
short extensible foot used mainly for burrowing into the sandy deposits of
which the animal live. Ranges in length usually from about 2 – 5cm. The head
bears bunches of slender tentacles used for catching food.
The largest living species is Dentalium vernei which is about 13cm long and a
diameter of 1.5cm.
61
Class: Gastropoda
Constitutes the largest and most diverse group of the Mollusca with about
40,000 living species and more than 15,000 fossil species.
Predominantly marine group, however widely spread in fresh water habitats.
One large sub class pulmanata has become typically terrestrial. Body consist of
a ventrally well developed head and a broad muscular foot both which retain a
bilateral symmetry. Exhibit unusual features not found in any other class of
mollusk. They are coiling and torsion. Torsion is usually an early larval evend,
coiling occurs at a later phase in development
e.g. periwinkles, topshells, limpets, sea snails, slugs, land snails e.t.c.
Class: Bivalvia
-
Mainly marine which burrow in sand and mud but same have colonized
the fresh water with no terrestrial forms.
-
Second largest class of mollusca
-
Bilaterally symmetrical, laterally compressed with extensive lateral
mantle lobes which secrete a single shell of two valves and a ligament
which joins them dorsally at a hinge. Head is rudimentary. Ciliary
feeders, the foot is compressed and adapted for burrowing. Fertilization is
external
E.g. mussels, scallops, oysters, clams, cockles
Class: Cephalopoda
-
All are active predaceous creatures able to swim and capture large
crustacean such as crabs
62
-
Body is characterized by a fore – shortening of the anterior – posterior
axis and an extension of the dorso–ventral axis
-
Head well developed and bears a pair of highly developed eyes and a
number of tentacles. Foot is represented by a siphonal apparatus that
assist in swimming. Some have ink sac (cuticle fish)
-
Sense organs are highly developed. Shell occur with the exception of
Nautilus where it encloses the body is reduced and internal and in
octopuses it is absent.
e.g. squid, pearly Nautilus, Octopus, cuticle fish
63
WEEK 11 Phylum chordata
General characteristics
-
Largest and ecological mort important phylum in line of evolution.
-
It is distributed in all habitats- marine fresh water and terrestrial.
-
Include all the large animals present on earth today with the possible
exception of the cephalopods.
-
Possession of a notochord at least sometimes or another during their
bicycle. It may persist throughout life example lancelet, lamprey or be
replaced either wholly or partially in the adult animal by a backbone
example fishes reptiles, birds and mammals
-
Pharyngeal region has in its lateral walls a series of paired openings
(gill slits) communication with the exterior to form visceral cleft in
aquatic forms, it becomes modified to provide respiratory survey aces
as gills or brachial clefts.
-
Central nervous system is always dorsal in position, hollow and
tubular in structure. The anterior end of the cord is usually enlarged to
form brain.
-
Bilaterally symmetrical with three germ layers and a segmented body
marked externally.
-
Circulation of blood in blood vascular system in maintains by a central
muscular propulsive organ-heart that is ventral (closed circulation)
except urochordata
-
Post and tail usually projecting beyond the anus which is extremely
flexible and muscular. In aquatic forms, it constitute the main
propulsive organ. In terrestrial firm, it may be reduced in the adult.
-
Complete digestive system.
-
Cartilaginous or bony endoskeleton formed in mesoderm.
-
Exoskeleton often present, well developed in fishers, reptiles and birds
64
-
Sexes usually separate (few hermaphrodite or protandric) oviparous or
viviparous
The major classes of this phylum which comprises of the vertebrate include
Class – Pisces (fishes)
Class – Amphibia (Amphibians)
Class – Reptilia (Reptiles)
Class – Aves (Birds)
Class – Mammalia (Mammals)
Class Pisces
General characteristics
-
Cold Blooded (poikilothermic)
-
Aquatic, either fresh water or marine
-
Skin covered with scales
-
Body streamlined
-
Presence of paired and unpaired fins supported by soft or spiny ray
-
Dorsal, caudal and anal fins are unpaired while the pectorals and
pelvics are paired
-
Endoskeleton by gills, opens to the outside by gill-slits
-
Gill slits are never more than seven pains usually five pains are
present
-
Swim bladder or airbladder usually present
-
Lateral line well developed
-
Heart is venous and two chambered
65
Diagram Tilapia
66
WEEK 12 Class Amphibia
General Characteristics
-
Skin moist and glandular, no external scales
-
Two pairs of limbs for walking or swimming .No fins, toes four to five
or fewer.
-
Nostrils two, connected to mouth cavity, eyes often with movable lids,
ear-drums, external on toads and frogs. Mouth usually with small
teeth, tongue often protrusible
-
Skeleton largely bony, skull with two occipital condyles. Ribs if
present not attached to sternum
-
Hearth typically three chambered
-
Respiration by gills, lungs, skin or mouth lining separately or in
combination
-
Body temperature variable
-
Excretion b y mesonephric kidneys
-
Fertilisation external or internal mostly oviparous usually an aquatic
larva firm with metamorphosis to adult form.
Diagram of Frog
67
Class: Reptilia
Genera Characteristic
-
Body covered with dry cornified skin usually with ectodermal scales
-
Limbs provided usually with five toes and adapted for climbing,
running or paddling. Absent in some lizards and snakes
-
Skeleton well ossified
-
Respiration by lungs and gills, cloacal respiration is some aquatic
turtles
-
Heart incompletely 4 chambered
-
Body temperature variable
-
Excretion by metanephric kidneys
-
Sexes separate, fertilization internal
-
Amniotic eggs covered with calcareous or leathery shells
e.g Lizard, crocodile. Snakes and turtle
Diagram of Lizard
Class – Aves (birds)
Characteristics
-
Body spindle shaped with four division – head, neck, trunk and tail
68
-
Body covered with feathers
-
Two pairs of limbs, forelimbs modified as wings for flight, hind limbs
adapted for perching, walking or swimming (with lobes or webs)
-
Skeleton light, strong, fully ossified with air sacs. Many bones fused,
providing rigidity
-
Upper and lower jaws drawn in front to form beak or bill with horny
sheath. No teeth.
-
Skull with are occipital candyle
-
Neck usually long and flexible
-
Respiration by compact highly efficient lungs attached to ribs and
connected to thin walled air sac
-
Voice boxes at base of trachea.
-
Body temperature constant
-
Excretion by metanephric kidneys. Fertilization internal, female with
only left ovary and oviduct.
-
Young at hatching cared by parent
Diagram of a bird
69
Class Mammalia
-
Body covered with hair but reduced in some. Skin with many glands
(sebaceous, sweat, scent and mammary)
-
Skeletal features of the skull with two occipital condyles seven
cervical vertebras and often an elongated tail
-
Mouth with teeth on both jaws
-
Movable eyelids and fleshy external ears (pinked)
-
Fore limbs (reduced or absent in same) adapted for many forms of
locomotion
-
Four chambered heart, persistent left aorta
-
Respiratory system of lungs and voice box.
-
Muscular partition (DIAPHRAGM) between thorax and abdomen
-
Excretory system of metanephric kidneys with ureters that opens into
a bladder
-
Nervous system of well developed brain and twelf pains of cranial
nerves
-
Sexes separate Reproductive organ vagina.
-
Internal fertilization. Eggs develop in a uterus with placental
attachment.
-
Young nourished by milk from mammary glands with exception of
Duckbilled platypus and spiny anteaters that lay eggs and do not
possess true mammary glands
70
WEEK 13 External Features of a Tilapia
It is found in aquatic environment (fresh water)
Bony fish, spindle shaped, flattened laterally to give it a streamlined shape that
allows it to move smoothly through the water. Body is covered with scales with
paired and unpaired fins. Unpaired fins are the dorsal, ventral and tail fins while
the pairs fins are the pectoral and pelvic fins.
Diagram of tilapia
External Features of Frog
The skin of frog is soft, smooth and moist. The head bears a wide mouth, small
valvular nostrils, large spherical eyes and behind each eye are flat eardrum or
tympanic membrane. Each eye has a fleshy, opaque upper eye lid and a lesser
lower lid. Continuous with the latter and folded behind it when at rest is a
transparent portion which functionally resembles the nictating membrane of
higher vertebrates. At the posterior end of the body is the vent or cloacae
opening through which are discharged undigested food wastes, urine and eggs
or sperm.
At mid body is the sacral hump, where the pelvic girdle is hinged to the sacrum.
The short front led (arm) comprises of an upper arm, fore arm, wrist and hand
with 4 digits and vestigial thumb.
The inner digit (thumb) is thickened on males especially in the breeding season.
The hind leg includes a thigh, lower leg, ankle and long foot with a narrow sole
71
and five slender toes connected by broad thin webs. The palm and soles bear
cornified tubercles that protect the feet against abrasion and provide traction on
wet, slippery surfaces.
Diagram of a frog
External Features of a Lizard
Body is made up of a head and trunk joined together by a definite neck. The
trunk ends in a long tapering tail.
On the head, there is a wide terminal mouth, a pair of nostrils, a pair of slightly
protruding eyes with movable eye lids and a pair of ear drums found in shallow
depression on the skin. Below the eardrum is a fold of skin, the gular fold which
is lowered during courtship or when the animal is frightened. Above the neck is
a median crest of skin, the nuchal crest, which the male raises when fighting
with each other.
The trunk bears a pair of fore and hind limbs which terminate each in five
clawed digits on the underside. Just behind the hind limbs is a transverse slit,
the cloaca. In the male, there is a hemi cod at each end of the cloaca.
The whole body is covered by overlapping scales. Adult males are larger and
more brightly coloured than females when are smaller and dull coloured
72
Diagram of a lizard
External Features of a Domestic Fowl
Has distinct head, long flexible neck, a stout spindle shaped body (trunk). The
two fore limbs are attached high on the back and have long flight features.
Wings folded in Z shape when at rest.
On each hind limbs, the two upper segment are muscular. The slender lower leg
contain tendons but little muscles and is covered with cornified scales, and four
toes that ends in horny claws.
The short tail bears a fanlike group of long tail feathers mouth is extended as a
pointed bill with horny covering. On the upper mandible are two slit like
nostrils. Eyes are large and lateral. Each with upper and lower eye lids. Below
these is the nictating membrane which can be drawn independently across the
eye ball from the anterior corner. Below and behind each eye is an ear opening
hidden under special feathers. There is a fleshy median comb and lateral wattles
on the head. Below the base of the tail is the vent.
73
Diagram of a Bird
External Features of a Rabbit
Body consist of the head, neck, truck and the tail and is covered with fur
Head bears a terminal mouth which is bordered by a pair of upper and lower
lips. The upper lip has a slit or cleft in the centre exposing the incisor teeth in
front. Above the mouth lies a pair of nostrils. The eyes have an upper and lower
eye lids and a nictating membrane.
In rabbit, the senses of smell and sight are well developed. At the sides of the
mouth on the upper lip are whiskers or vibrissae which are sensitive to touch.
These help the rabbit to move in its dark burrow.
It has a pair of external ears that consist of a funnel like pinna. The narrow neck
connects the head to the trunk. The trunk bear two pairs of limbs and end in a
short tail is made up of two regions, the thorax and the abdomen which hare
separated by a muscular sheet, the diaphragm. Within these two regions lie the
internal organs or viscera. On the ventral side of the abdomen, the adult female
has three to five pairs of teats which bear the openings to the mammary gland.
The anus lies under the tail while the urinogenital opening is just ventral to it.
On either side of the tail is a hairless patch of skin into which opens perineal
gland. The secretion from this gland gives the rabbit it characteristic smell. Each
fore limb consists of the upper arm, fore arm and fore foot with five digits. Each
hind limb consists of the thigh, the shank and the hind foot with four digits. The
hind limbs are longer than the fore limbs and are much more powerful. Their
straightening results in the forward thrust necessary for jumping.
74
Diagram of rabbit
75
WEEK 14 Protochordates as a link between invertebrates and vertebrates
The protochordates (urochordata and cephalochordata) are considered to be
link between vertebrata and invertebrate. The protochordates shows lots of
embryonic affinities with vertebrata and invertebrate.
The cephalochordates possess all the four chordate hall marks (notochord,
dorsal tubular nerve cord, pharyngeal gill slits and post anal tail). But its
notochord is over developed into a forward extension for its specialized
burrowing mode of life. It effectively prevent the development of a proper
brain its kidney type bear little resemblance to the vertebrate glomerular
tubular nephron and there is a non vertebrate like proliferation of gill slits.
The adult ascidians (Tunicates) are virtually immobile forms surrounded by
a tough cellulose containing tunic of variable colour. Their adult life is spent
in one spot attached to same submarine surface filtering vast amounts of sea
water from which they extract their plank tonic food. As adult, they lack
notochord tubular nerve cord, post anal tail, sense organs and segmental
musculature superficially, they resemble sponges (invertebrate) for mere
then they resemble the vertebrates.
Acorn Worm, common name for simple, wormlike marine animals in the
hemichordate phylum. They are of special interest because of their close
relationship to chordates. This connection is evident in the adult anatomy. Some
representative acorn worms have gill slits, traces of a supporting structure
resembling a notochord, and a tubular nerve cord, which are features
characteristic of vertebrates. The larval stages of acorn worms, however, are
very much like those of echinoderms such as starfish, indicating a remote
common ancestry of echinoderms and vertebrates.
The hemichordates are divided into two classes comprising about 50 species.
The first class, the acorn worms, consists of animals that average 10 cm (4 in) in
length, although some species may be up to 1.5 m (up to 5 ft) long. They
construct burrows, commonly U-shaped, in sand of shallow seafloors using an
76
extendable, muscular proboscis attached to a thick collar that resembles an
acorn—hence the name. They secrete a slime that collects food particles on the
proboscis and collar, but some species filter sediments and sand through a
complicated pharynx with many gill slits. The second class consists of small,
usually colonial animals of the deep sea. They are not worm-shaped but stout,
and they usually construct tubes. Food is captured by tentacles that project from
the tube. The body is much simplified, and gill slits are reduced to one pair or
none.
Diagram of an Acorn Worm
77
WEEK 15 Preservation methods of common vertebrates and invertebrates
Preservation is a method of keeping animal tissues as closely as it is while
living. The specimens will last for longer time, can be stored indefinitely by
destroying any bacteria, fungi that could degrade the specimen and protect from
further action by microorganisms.
A preservative is a chemical compound that is capable of keeping the animal
tissues as closely as it is while living.
The procedure for preserving animal specimen varies greatly from one animal
group to another. In most cases, the specimen must first be killed or narcotized
in such away as to leave the tissue relaxed and suitable for display. The material
is then fixed in this condition and then finally preserved. The final preservation
is normally made either is a solution of ethanol and methanol usually known as
alcoholic or in a solution of methanol formaldehyde known as formalin for
preservation purpose.
Industrial methylated spirit diluted to an appropriate concentration can also be
used satisfactorily.
Appropriate killing, narcotizing, fixing and preservation of various animal
groups are as follows:
Animal Group
Killing or Agent Fixative
Preservative
Notes
-
Best
Narcotizing A.
Protozoa
-
-
stained
preserved
in
smears
on
slides
Porifera
70% alcohol
70%
alcohol
70% alcohol
Change
the
alcohol
after 24 hours. Sponges
can also be preserved
dry.
78
Coelenterates
Hot
Bouins Bouin’s
solution
70% alcohol
solution
Flood live specimen
with
hot
Bouin’s
solution starting at base
moving
up
to
the
tentacles
Platyhelminthes
2 – 4% methanol 2 – 4% 2% methanol Allow
(cestodes)
or formal acetic methanol
or
acid
alcohol
specimen
to
70% relax in cold water and
then wrapped on a
supported then fix
Nematodes
Hot
2% Hot
2% 2% methanol Larger forms may be
methanol or hot methanol
70% alcohol
or
or
70% dropped directly into
hot alcohol
the hot fixative
70%
alcohol
Annelids
(leaches
Methanol crystal 2 – 4% 70
and or MgSO4
methanol
–
90% Place
alcohol
earth worms)
worms
shallow
sufficient
in
dish
a
with
water
to
cover them. Add little
alcohol,
crystals
menthol
or
MgSO4
every 2 minutes till the
worms are limp and
insensitive
to
touch
transfer to fixative and
leave over night, then
transfer to alcohol
Mollusks (snails) Epson salts or 2 – 4% 70% alcohol Place snail in a stopper
asphyxiation
methanol
or
methanol
2% jar completely filled
with H2O and leave for
79
24 hours or may be
placed in warm H2O,
allow to expand before
slowly adding Epson
salt.
Transfer
to
fixative for 24 hrs and
then to preservative
Crustaceans
2% methanol
small fresh water
and
2%
70
–
90% Add sufficient formalin
methanol
alcohol
to
marine
specimen
in
its
habitat water to form
forms
2% methanol transfer
to
alcohol
for
preservation
Insects
juvenile
all 70
–
80% 75 – 80% 75
forms alcohol
alcohol
–
80% Place insects in alcohol
alcohol
in small vials. Change
except
orthoptera
alcohol after 24hrs. if
and
permanent slide is to
isoptera
be made add KOH is
the preparation
All other insects Killing
juvenile
bottle -
or containing ethyl
adults
Dry
mount
on cards or
ethanoate
pins
(acetone)
naphthalene
to
add
prevent
attack
by
pests
Other arthropods 70% alcohol
70%
spiders,
alcohol
mites
scorpions, ticks
70% alcohol
Specimens should be
dropped directly into
the alcohol
80
Fish
Formation
70% alcohol
or 2%
2%
Methanol
or
Place
fish
in
large
Methanol or vessel to which a little
70% 70% alcohol
alcohol
formalin
added,
has
been
when
dead
transfer to fixative or
transfer directly in 70%
alcohol
Amphibians
KOH
methanol
with 3 – 4% 2% methanol Place
methanol
or
specimen
in
2% KOH with methanol.
Methanol or Allow to sink, relaxed
70% alcohol
to the bottom then
position and transfer to
fixative. Or specimen
may
be
placed
in
plastic bags in freezer
for
24hrs
thawed,
positioned and fixed
Reptiles
Freezing
4%
3% methanol Place in a plastic bag in
methanol
a freezer and leave for
24 hrs and then allow
to thaw place in 4%
methanol
and
inject
same of the fixative
into body cavity. In
case of large lizard it
should be injected into
each limbs and into
base of tails.
Birds
-
-
Dry mounts
81
Mammals
CO2 in a killing 3%
chamber
methanol
3% methanol After
placing
killing
in
a
chamber,
specimens should be
left in the chamber for
at least 10 minutes
after collapse to ensure
death has taken place.
The body cavity and
larger muscles should
be
injected
fixatives
82
with