Download What is an animal? Part 1

Animal Form And Function
Part 1 - Invertebrates
Biology
PFHS
Lecture Outline:
What is an animal?
Origin of animal body form diversity
Correlation between form and function
Organization of body plans into grades
Views of animal diversity
What is an animal? How do we define an
animal?
While there are exceptions to nearly every
criterion for distinguishing an animal from
other life forms, the following criteria, when
taken together, create a reasonable definition.
1. Animals are multicellular eukaryotes.
2. Animals are Heterotrophs:
Cannot make their own food - cannot convert simple
inorganic molecules into complex organic molecules.
They must take in preformed organic molecules through
ingestion, eating other organisms or organic material that
is decomposing.
Plants are Autotrophs – they can synthesize their
nutrition from simple inorganic molecules into complex
organic molecules.
3. Animal cells lack cell walls that provide
structural supports for plants and fungi.
Cell Membrane: Every cell is enclosed in a
membrane. The membrane is a double layer
of lipids (lipid bilayer) but is made quite
complex by the presence of numerous
proteins that are important to cell activity.
Animal Cell
Cell Wall: Prokaryotic cells, fungi cells, and
plant cells have a rigid cell wall in addition to
the cell membrane that is made up of
polysaccharides. The cell wall provides and
maintains the shape of these cells and serves
an extra protective barrier.
Plant Cell
4. Locomotion:
Animals are capable of moving from one place to
another. This complex function is achieved by
coordinated functioning of two unique tissue
types.
i. Nervous tissue for impulse conduction
ii. Muscle tissue for movement.
Exception: Some animals do not have locomotor
ability – sedentary.
5. Reproduction: Most animals reproduce sexually,
with the diploid stage usually dominating the life
cycle.
In most species, a flagellated haploid sperm fertilizes a
haploid egg. The fertilized diploid egg - zygote - undergoes
cleavage, a succession mitotic cell divisions, leading to the
formation of a multicellular, hollow ball of cells called the
blastula.
6. Characteristics that are true for most animals,
but not all…
• The multicellular bodies of animals are held
together with the extracellular proteins, especially
collagen.
• In addition, other structural proteins create several
types of intercellular junctions, including tight
junctions, desmosomes, and gap junctions, that
hold tissues together.
• Animals have skeleton – endoskeleton (bones) or
exoskeleton (shells) – that provides rigidity of
form.
Correlation between Form and function
Animals show a correlation between body form (structure) and
function.
Form fits function at all the levels of life, from molecules to
organisms.
Knowledge of a structure provides insight into what it does and how
its works.
Conversely, knowing the function of a structure provides insight
about its construction.
Therefore, sometimes distinction between anatomy and physiology
is blurred.
Animal Classification:
•
Living animals are classified in to 35 different phyla based body
plans.
•
Most are marine phyla, only a few terrestrial phyla – most species
diversity is in the ocean. We will cover about 13 of these phyla
•
Four basic features of animal body plan are the basis for
classification of animals into various phyla.:
Body symmetry
Germ Layer
Coelom
Development pattern
1. Body Symmetry:
•
Mainly based on anatomical features in adults and certain
details of embryonic development.
•
The symmetry of an animal generally fits its lifestyle.
i. Radial Symmetry
ii. Bilateral Symmetry
iii. Asymmetry (not common)
i. Radial Symmetry:
•Many radial animals are sessile or planktonic and
need to meet the environment equally well from all
sides.
Multiple planes
of symmetry
ii. Bilateral symmetry:
•Animals that move actively are bilateral.
•Head, anterior end, encounters the environment -food, danger, and other stimuli.
•Bilateral symmetry is associated with cephalization, concentration of sensory
equipment on the anterior end – head.
•Cephalization leads to the development of central nervous system.
Dorsal
Posterior
Single plane of symmetry
Anterior
Ventral
2. Germ Layers:
Three germ layers:
Ectoderm: forms the outer covering and, the central nervous system (if
present).
Endoderm: lines the digestive tract and the organs derived from it, such
as the liver and lungs of vertebrates.
Mesoderm: lies between the endoderm and ectoderm and develops into
muscles and other organs e.g., kidneys and gonads.
i. Diploblastic: have two germ layers – ectoderm and endoderm. e. g.,
the radiata.
ii. Triploblastic: have three germ layers – ectoderm, endoderm and
mesoderm. e. g., the bilateria
3. Coelom: The germ layers form a cavity around the
internal organs – Coelom.
Coelom has many functions.
•Its fluid cushions the internal organs, helping to prevent
internal injury.
•The noncompressible fluid of the body cavity can
function as a hydrostatic skeleton against which muscles
can work.
•The present of the cavity enables the internal organs to
grow and move independently of the outer body wall.
A coelom – the body cavity - could be a true coelom or a
false coelom.
Based on the type of coelom and presence or absence of a
coelom and animal could be classified as:
•Coelomate
•Pseudocoelomate (false coelom)
•Acoelomate (no coelom)
Coelomates are organisms with a true coelom, a fluid-filled body
cavity completely lined by mesoderm.
•The inner and outer layers of tissue that surround the cavity
connect dorsally and ventrally to form mesenteries, which
suspend the internal organs.
Pseudocoelomates, have a body cavity, but it is not completely
lined by mesoderm, e.g., rotifers (phylum Rotifera) and the
roundworms (phylum Nematoda).
Acoelomates have a solid body and lack a body cavity, e.g.,
(the phylum Platyhelminthes) .
4. Development pattern:
DEUTEROSTOMES
PROTOSTOMES
(a) Cleavage
(zygote divides
into ball of cells)
Spiral
cleavage
(b) Gastrulation
(cells invaginate
to form gut)
Radial
cleavage
Mouth
Pore
becomes
mouth
Pore
becomes
anus
Anus
(c) Coelom
formation
Gut
Mesoderm
Block of solid
mesoderm splits
to form coelom
Coelum
Gut
Mesoderm
Mesoderm pockets
pinch off of gut to
form coelom
Major Steps in Animal Form and Function
Choanoflagellates
Poriferans
Protist
ancestor
Ectoderm
Multi-cellularity
Endoderm
Cnidarians
Ectoderm
Mesoderm
Endoderm
Two tissue
layers
Mouth
Protostomes
Anus
Body cavity
Three tissue layers,
a body cavity, and
bilateral symmetry
Developing
mouth
Ectoderm
Mesoderm
Endoderm
Deuterostomes
Anus
New forms of embryological, development,
including the formation of the mouth secondarily
Porifera
Porifera
• Poriferans are commonly referred to as
sponges.
• fossil sponges are among the oldest
known animal fossils, dating from thelate
precambrian.
• The approximately 5,000 living sponge
species are classified in the phylum
Porifera
Porifera
• Sponges are characterized
by the possession of a
feeding system unique
among animals.
• Poriferans don't have
mouths; instead, they have
tiny pores in their outer
walls through which water
is drawn.
• Cells in the sponge walls filter goodies from the water as the water is
pumped through the body and out other larger openings. The flow of
water through the sponge is unidirectional, driven by the beating of
flagella which line the surface of chambers connected by a series of
canals.
• Sponge cells perform a variety of bodily functions and appear to be
more independent of each other than are the cells of other animals.
(b)
Central cavity
Gelatinous middle layer with
skeletal materials and motile
cells that can become
gametes
Microvilli
Collar
cell
Motile
cell
Pore
Central
cavity
Collar cells are similar in form
to choanoflagellate protists,
suggesting that animals derived from
colonial choanoflagellates
Skeletal
material
(spicule)
Fig. 13.04
Porifera
• Form symbiotic
relationships with
bacteria and fungi
• Produce a wide array
of chemical defense
compounds
• Useful for Medicinal
lead compounds
– Discodermalide
a potent anticancer
compound in clinical
trials
Introduction to Cnidaria
• Jellyfish, corals, and other stingers. . .
• Cnidarians are incredibly diverse in form, as evidenced by
colonial siphonorphores, massive medusae and corals, feathery
hydroids, andbox jellies with complex eyes.
• Yet, these diverse animals are all armed with stinging cells
called nematocysts. Cnidarians are united based on the
presumption that their nematocysts have been inherited from a
single common ancestor.
• There are four major groups of cnidarians:
– Anthazoa - which includes true corals, anemones, and sea pens
– Cubozoa - the amazing box jellies with complex eyes and potent toxins
– Hydrozoa - the most diverse group with siphonophores, hydroids, fire
corals, and many medusae
– Scyphozoa - the true jellyfish.
Cnidaria
There are four major groups of cnidarians:
Anthazoa - which includes true
corals, anemones, and sea pens
Coral Reef Ecosystems
• Coral reefs and other marine ecosystems, however, contain
more varied life forms than do land habitats.
– All but one of the world's 35 phyla are found in marine environments
-- 15 exclusively so.
• Coral reefs are found in shallow waters, extending to depths
of 30 meters and cover 15 percent of the world's coastline
(0.2% of the total area of oceans)
• Fish production on these reefs and on the adjacent
continental shelf could amount to nearly 10 percent of global
fisheries production if fully exploited.
• Coral reefs also protect coastal areas from erosion. In the
case of coral atolls, coral provides the foundation of the
island itself. In the Indian Ocean, 77 percent of isolated
islands and island archipelagoes are built exclusively of reef
depositions.
Affiliated Ecosystems
Coral reefs stand out from other marine environments because of
their species diversity, but many coral reef species also
depend on other affiliated ecosystems.
Often, coral reefs, mangroves, and sea grass beds are linked
physically and biologically:
1. reefs serve as breakwaters that allow coastal mangroves to
develop;
2. the calcium of the reef provides the sand and sediment in
which mangroves and sea grasses grow; and
3. the mangroves and sea grass communities provide energy
input into the coastal ecosystem and serve as spawning,
rearing, and foraging habitat for the many of the species
associated with the reefs.
Coral Reefs
Mangroves
Sea Grass Beds
Coral Reef Ecosystems
Some Facts and Figures on Coral Reefs as a Fishery Resource
• Healthy coral reefs can produce more than 20 metric tons of fish
and other edible marine products per square kilometer per year.
Unfortunately, 95% of the country's coral reefs are various stages
of deterioration due to destructive and illegal practices, siltation
and sedimentation, and pollutants from industrial and domestic
wastes and construction activities, among others.
The Destruction of Coral Reefs
• Fishing practices destructive to coral reefs include muro-ami,
cyanide fishing, trawl fishing, indiscriminate harvesting, and
dynamite fishing. Blast or dynamite fishing alone destroys an
average of one to three square meters of corals per blast. consider
this -- coral grows very slowly at an average of one to two inches
a year. Thus, it takes hundreds of years to grow a coral reef!
Cnidaria
There are four major groups of cnidarians:
Hydrozoa - the most diverse group
with siphonophores, hydroids, fire
corals, and many medusae
Cnidaria
There are four major groups of cnidarians:
• Scyphozoa – the true
jellyfish
Cnidaria
There are four major groups of cnidarians:
Cubozoa - the amazing box jellies
with complex eyes and potent
toxins
(e) Radial body plan
Jellyfish, from top
Nerve
cell
Nematocyst
discharged
(f)
Tentacle
Nematocystbearing cell
Mouth
Epidermis
Epidermis
Gastrodermis
Mesoglea
Polyp form
Gastrovascular
cavity
Medusa form
Mesoglea
Mouth
Muscle
cells
Digestive
enzymesecreting
cell
Fig. 13.05
Slide 4
Treatment for Stings
• Primary first aid for any jellyfish sting should be to minimize the
number of nematocysts discharging into the skin and to reduce the
harmful effects of the venom. If stung by a jellyfish, the victim should
carefully remove the tentacles that adhere to the skin by using sand,
clothing, towels, seaweed or other available materials. As long as
tentacles remain on the skin, they will continue to discharge venom.
• A variety of substances have been used to reduce the effects of
jellyfish stings. Meat tenderizer, sugar, vinegar, plant juices and
sodium bicarbonate have all been used with varying degrees of
success. Methylated spirits and other forms of alcohol formerly
recommended for inhibiting stinging cells actually stimulate them and
may increase pain and cause severe skin reactions. Picric acid and
human urine also cause a discharge of nematocysts and should not be
used. Victims of serious stings should make every effort to get out of
the water as soon as possible to avoid drowning. If swelling and pain
from more serious stings persists, prompt medical attention should be
sought. Recovery periods can vary from several minutes to several
weeks.
Adult female
medusa
Tentacle
Gonad
Adult male
medusa
Egg
Sexual
reproduction
Zygote
Sperm
New
medusa
Development
Planula
larva
Cilia
Asexual
reproduction
Stack of
developing
medusae
Differentiation
Hydra-like
polyp
Fig.13.06
Protostomes
Fruit fly larva,
cross section
First opening
becomes the mouth
Anus
Fig. 13.08a
Platyhelminthes
(Flatworms)
Platyhelminthes
• Reproduction is by both sexual and asexual
means. For sexual reproduction, planarians are
hermaphroditic organisms.
• Asexual reproduction is accomplished by
fragmentation followed by regeneration, and many
of these free-living flatworms have remarkable
regenerative abilities. As a result of this, the
turbellarian flatworms have contributed a great
deal of information to our knowledge of
regeneration.
Hermaphrodite
• An organism which has both male and female
organs, and produces both male gametes (sperm)
and female gametes (eggs).
• The organism can have both types of organs at the
same time (simultaneous hermaphrodite) or have
one type early in life and the other type later in life
(sequential hermaphrodite).
Platyhelminthes
Class Trematoda (Flukes)
• The flukes are all parasitic organisms; the adult stage
living in or on a wide variety of vertebrate animals. Of
the groups the blood flukes are the most important as
they are the causative agents for the human disease
known as Schistosomiasis. This debilitating disease
affects some 400,000,000 persons in Asia, Africa, parts of
South America and the Caribbean
Class Cestoda (Tapeworm)
• Tapeworms are elongate, intestinal parasites consisting of
an anterior scolex for attachment and numerous body
segments called proglottids. They are highly modified to
a parasitic existence and have no digestive system.
Tapeworms also have complicated life histories.
Tape Worms
•The adult lives in the small intestine. It is
hooked onto the intestinal wall by a structure
called a rostellum which is sort of like a hat
with hooks on it. The tapeworm also has six
rows of teeth to grab on with.
•Once docked like a boat to the host intestinal
wall, the tapeworm begins to grow a long tail.
•The tapeworm absorbs nutrients through its
skin as the food being digested by the host
flows past it.
•Older segments are pushed toward the tip of
the tail as new segments are produced by the
neckpiece. By the time a segment has reached
the end of the tail, only the reproductive tract is
left. When the segment drops off, it is basically
just a sac of tapeworm eggs.
28 foot tape worm
(b) The flatworm body plan
Dorsal
Posterior
Left
Right
Head
Anterior
Ventral
Direction of
movement
(c) Organ sytems
Nervous
system
Seminal
vesicle Mouth
Muscular tube
(phaynx)
Digestive
system
Ovary
Eyespot
Fig. 13.09
Brain
Platyhelminthes
(Why are flatworms flat??)
• The simplest animals that are bilaterally symmetrical
and triploblastic (three tissue layers)
• Flatworms have no body cavity (NO COELEM) other
than the gut
• They lack an anus; the same pharyngeal opening both
takes in food and expels waste.
• Because of the lack of any other body cavity, in larger
flatworms the gut is often very highly branched in order
to transport food to all parts of the body.
• The lack of a cavity also constrains flatworms to be flat;
they must respire by diffusion, and no cell can be too
far from the outside, making a flattened shape
necessary.
Protostomes
Fruit fly larva,
cross section
First opening
becomes the mouth
Anus
Fig. 13.08a
Annelids
• The phylum includes earthworms and their relatives,
leeches, and a large number of mostly marine worms
known as polychaetes. Various species of polychaete are
known as lugworms, clam worms, bristleworms, fire
worms, sea mice, and "EWWW! I stepped on that
THING!"
• Annelids can be told by their segmented bodies.
Polychaetes (meaning "many bristles") have, predictably,
many bristles on the body, while earthworms and leeches
have fewer bristles. There are about 9000 species of
annelid known today.
• Annelids are triploblastic and contain a coelom
• They also have well developed organs.
Annelids
The internal organs of annelids are well developed. They include a closed,
segmentally-arranged circulatory system and a digestive system with mouth and
anus. Gases are exchanged through the skin. The nervous system includes a pair of
cephalic ganglia attached to double nerve cords that run the length of the animal
along the ventral body wall. Annelids have some combination of tactile organs,
chemoreceptors, balance receptors, and photoreceptors; some forms have fairly
well developed eyes, including lenses.
Anus
5 “Hearts”
Crop
Gizzard
Brain
Mouth
Blood Nerve Coelom Intestine
vessel cord
(d) A segment
Partitions
(septa)
Excretory units
(nephridia)
Blood vessel
Intestine
Funnel
Nerve cord
Excretory
pores
Bristles
(setae)
Fig. 13.11d
Protostomes
Fruit fly larva,
cross section
First opening
becomes the mouth
Anus
Fig. 13.08a
Phylum: Mollusca
• Mollusks are triploblastic coelomates, some have very
well-developed brains and are thought to be very
intelligent (ie octopus)
• There is one thing that all mollusks have in common: a
foot. The foot is used for different purposes in each
class, as you will see.
• Here are four classes of mollusks:
–
–
–
–
Gastropoda
Polyplacophora
Bivalvia
Cephalopoda
(c)
The mantle forms a cavity
surrounding body organs,
and secretes the shell
Digestive
gland
Gonad
Blood-filled
cavity
Heart
Coelom
Excretory
organ
Anus
Shell
Tentacle
Mantle
cavity
Gill
Water
flow
Head
Mouth
The rasp-like radula
helps obtain food
Nerve cords
Gut
The muscular foot aids
In locomotion
Fig. 13.12c
Gastropoda
• There have been nearly 35,000 living species and 15,000
fossil species identified, including spirally-coiled snails,
flat-shelled limpets, shell-less nudibranchs, whelks,
abalones, pteropods and terrestrial snails and slugs.
• Most have a single, usually spirally coiled shell into which
the body can be withdrawn, but the shell is lost or reduced
some important groups.
• Gastropods have a muscular foot which is used for
"creeping" locomotion in most species.
• Most gastropods have a well-developed head that includes
eyes, 1-2 pairs of tentacles, and a concentration of nervous
tissue (ganglion).
• Gastropods are dioecious, and some forms are
hermaphroditic. Hermaphroditic forms exchange bundles
of sperm to avoid self-fertilization;
Gastropoda
Torsion in Gastropods
• Gastropods initially have a basic bilateral symmetry
like most mobile animals. The mouth sits at one end
anteriorly and the anus sits at the other end posteriorly.
During development however, the digestive system
and the rest of the internal organs turn-sometimes 90
degrees, sometimes up to 180 degrees so that the anus
is then situated over the mouth.
• This process occurs early in development in most
cases and usually occurs in two steps.
• A foot retractor muscle develops and at a certain stage
in development, this retractor muscle is pulled and the
internal body organs and digestive tract turn 90
degrees in a counterclockwise fashion. This turn
usually occurs within a few minutes or hours.
Why Torsion?
• Of course the obvious question is why would a
gastropod rearrange its digestive system and other
organs-including gills and nerves, so that its anus
is above its head. This doesn’t seem to be a good
adaptation to anything.
• Besides the hygiene considerations, it also limits
growth since the body is doubled over on itself,
and nerves are bent into a figure eight. The result
is the visceral hump prevalent in most gastropods.
Polyplacophora
(Chitons)
• They are flattened, elongated animals with eight overlapping
dorsal shell plates or "valves," bordered by a thick "girdle"
formed from the mantle.
• The mantle cavity encloses the foot, with which chitons cling to
rocky surfaces.
• Chitons have a single heart, a pair of kidneys, a simple nervous
system comprising two pairs of nerve cords that connect near the
mouth, and sense organs including eyes and chemosensory
organs.
• Chitons are dioecious.
• All are marine. Most species live in the rocky intertidal zone, but
some can be found at great depths. They graze on algae, scraping
algal cells from the substrate with a radula.
Polyplacophora
Bivalvia
• Clams, scallops, mussels
• Like other molluscs, bivalves have a fleshy mantle
encasing the visceral mass and a muscular foot.
• Unlike gastropods and cephalopods, bivalves
secrete two shells rather than one.
• Additionally, bivalves have lost the radula, which
is presumed to be a primitive feature among all
mollusks.
Bivalves
Scallops
Clams
Muscles
Bivalves
Cephalopods
What group of animals can change color faster than a chameleon
plus change texture and body shape?
has three hearts pumping blue blood?
is jet powered, has members in all oceans of the world ?
has inspired legends and stories since recorded history?
is thought to be the most intelligent of invertebrates and yet is
related to animals such as clams and oysters?
has members that can squeeze through the tiniest of cracks?
is related to garden slugs yet has eyes and other senses that rival
our own?
and can make their own 'smoke screen' or 'decoys' out of ink?
Cephalopods, the group in which scientists classify octopuses,
squid, cuttlefish and nautiluses can do all these things and more.
Protostomes
Fruit fly larva,
cross section
First opening
becomes the mouth
Anus
Fig. 13.08a
Nematoda
• Roundworms (nematodes) are bilaterally symmetrical,
worm-like organisms that are surrounded by a strong,
flexible noncellular layer called a cuticle.
• A true coelom is lacking, instead, nematodes have a
"pseudocoel" formed directly from the cavity of the
blastula (rather than as a result of the division or folding of
mesoderm).
• No cilia or flagellae are present.
• Some nematodes have specialized cells that excrete
nitrogenous wastes; in others, canals or canals plus these
specialized cells are present. Nematodes do not have flame
cells.
• Most nematodes are dioecious, but some are
hermaphrodites.
Nematoda
Although they are
small, nematodes are
incredibly abundant. If
all the nematodes in the
Willamette River were
combined into one huge
animal, it would be over
20 meters long (see
image left). Laid endto-end they would
encircle the earth’s
equator.
Nematoda
• Nematodes are almost unbelievably abundant. One study reported
around 90,000 individual nematodes in a single rotting apple.
• Another reported 236 species living in a few cubic centimeters of
mud. The number of described species is around 12,000, but too little
attention has been paid to these animals and the true number may be
closer to 500,000.
• Many nematodes are free living and play critical ecological roles as
decomposers and predators on microorganisms.
• But nematodes also include parasitic species, a number of which
affect humans directly or indirectly through their domestic animals.
These include the common roundworms, which probably infest more
than half the world's humans; hookworms; trichina, the worms that
cause trichinosis; and filarial worms, primarily tropical parasites that
cause diseases such as filariasis (elephantiasis) and onchocerciasis
(river blindness).
Nematoda
Protostomes
Fruit fly larva,
cross section
First opening
becomes the mouth
Anus
Fig. 13.08a
Arthropoda
. . . the REAL rulers of the Earth. . .
Diplopoda
Chilopoda
Arachnida
Insecta
Crustacea
Chordates
Arthropods
Echinoderms
Cnidarians
Annelids
Other
(Ctenophores,
Platyhelminths,
Brachiopods,
Nematodes,
Hemichordata)
Mollusks
Sponges
Nematodes Platyhelminthes
By nearly any
measure, the most
successful animals on
the planet are the
arthropods. They
have conquered land,
sea and air, and make
up over three-fourths
of all currently
known living and
fossil organisms, or
over one million
species in all.
Arthropoda
• Despite this unbelievable diversity, the basic body
plan of arthropods is fairly constant.
• Arthropods have a stiff cuticle made largely of
chitin and proteins, forming an exoskeleton that
may or may not be further stiffened with calcium
carbonate. They have segmented bodies and show
various patterns of segment fusion (tagmosis) to
form integrated units (heads, abdomens, and so on).
The phylum takes its name from its distinctive
jointed appendages, which may be modified in a
number of ways to form antennae, mouthparts, and
reproductive organs.
(d) Hormonal control
Periodic releases of ecdysone (molting hormone)
Molt
Molt
Molt
Larva
Larva
Adult
Pupa
High
Low
Very low
Level of juvenile hormone
Fig 13.16d
Insect Adaptations
The most distinguishing
characteristic of an insect's head
is the mouthparts. They may be
designed for chewing food, for
sucking it or lapping it up. The
housefly uses its it's mouthparts
are used for mopping; up liquid
food. The end of the labium
functions like a sponge. A
butterfly sucks up its food
through a part of the maxillae
that forms a tube. The
mosquito also sucks ups its
food. All of its mouthparts,
except the labium, form a
needle-like tube called a
fascicle. The ground beetle is a
carnivore; it has large
mandibles adapted for piercing
and cutting prey.
Insect Adaptations
• The legs of all insects are made up of
the same basic parts - femur,
trochanter, coxa, tibia and tarus, but
they can differ considerably.
• At left, is the rear leg of a
cockroach. It is long and lean, made
for running. They have spines which
point backward. They are used for
holding onto surfaces.
• Compare it to the rear leg of the
grasshopper. It has a large, stronglymuscled femur to help it leap into the
air.
• The Honeybee's back legs are covered
with hair. Pollen sticks to the them
and is collected into a special area on
the leg called a pollen basket.
• The Water Beetle's legs are fringed
with hair which helps push it through
the water.
• The Mole Cricket's legs are short and
spade-like, making them especially
useful for digging.
Insect Adaptations
Cockroach
Moth
Mosquito
Honeybee
Antennae are sensory structures to help the insect find
out more about its surroundings. The structure of
some, such as the cockroach, moth and mosquito are
adapted in different ways to increase the surface area
for sensory cells. The bee's antennae have a simpler,
more robust shape.
Insect Adaptations
Lacewing
Moth
Beetle
Most insects have membranous wings; such wings are very thin and like
cellophane. Many have venation, a system of thickened lines in the wings, such as
the lacewing. The wings of butterflies and moths are not membranous. Rather they
are covered with small dust-like scales.
Flies and mosquitoes have one pair of wings. Some insects - such as the ant and
termite - are wingless. Most insects have two pair of wings. They can be prominent
as in the lacewing and butterfly, or modified to be less obvious. The beetle's front
pair of wings provide a hard or leather-like covering that protects the back pair when
they are not being used.
Insects are Important
• the majority of insects are found in the warm and moist tropics.
Insects have adapted to a broad range of habitats, successfully
finding their own niche, because they will consume almost any
substance that has nutritional value.
• Insects perform a vast number of important functions in our
ecosystem. They aerate the soil, pollinate blossoms, and control
insect and plant pests; they also decompose dead materials,
thereby reintroducing nutrients into the soil. Burrowing bugs such
as ants and beetles dig tunnels that provide channels for water,
benefiting plants. Bees play a major role in pollinating fruit trees
and flower blossoms. Gardeners love the big-eyed bug and
praying mantis because they control the size of certain insect
populations, such as aphids and caterpillars, which feed on new
plant growth. Finally, all insects fertilize the soil with the
nutrients from their droppings.
Insects Blend into their Environment
Insects can be brightly colored
Sea urchin larva,
cross section
Second opening
becomes the
mouth
Blastopore
becomes the
anus
Echinodermata
•
•
•
•
•
Spiny skin = phylum name
No cephalization w/ oral & aboral surfaces
Internal skeleton
Water vascular system/tube feet
Radial symmetry
Water Vascular System
•Network of canals creating hydrostatic pressure to help the
starfish move
WATER VASCULAR SYSTEM
•Water enters through sieve plate or madreporite on aboral
surface into a short, straight stone canal
•Stone canal connects to a circular canal around the mouth
called the ring canal
•Five radial canals extend down each arm & are connected to
the ring canal
•Radial canals carry water to hundreds of paired tube feet
Echinoderm Classes
Non-vertebrate chordates
• Related to chordates
• Similar in structure to invertebrates
• Subject of controversy
Unifying Themes
1. Chordate evolution is a history of innovations that is built upon
major invertebrate traits
• They display many of the basic traits that first evolved in the
invertebrates: bilateral symmetry, cephalization, segmentation,
coelom, "gut" tube, etc.
2. Chordate evolution is marked by physical and behavioral
specializations
• For example the forelimb of mammals has a wide range of structural
variation, specialized by natural selection
3. Evolutionary innovations and specializations led to adaptive
radiations - the development of a variety of forms from a single
ancestral group
Characteristics of the Chordates
• Notochord, dorsal hollow nerve cord, pharyngeal gill slits,
blocks of muscle, postanal tail
Characteristics of the Chordates
The notochord
• All chordate embryos have a notochord, a stiff but flexible rod that
provides internal support
• Remains throughout the life history of most invertebrate chordates;
among, present only in the embryos of vertebrate chordates
Characteristics of the Chordates cont.
Dorsal Hollow Nerve Cord (=Spinal Cord)
• A fluid-filled tube of nerve tissue that runs the length of the
animal, dorsal to the notochord
• Present in chordates throughout embryonic and adult life
Characteristics of the Chordates cont.
Pharyngeal gill slits
• Pairs of opening through the pharynx
• Invertebrate chordates use them to filter food
• Juvenile fishes use them to them for breathing
• In adult fishes the gill sits develop into true gills
• In reptiles, birds, and mammals the gill slits are vestiges, occurring
only in the embryo
Characteristics of the Chordates cont.
Blocks of Muscle - Myotomes
• Surrounding the notochord and nerve cord are blocks of muscle myotomes
Postanal Tail
• The notochord, nerve cord, and the myotomes extend to the tail
• Found at some time during a chordate's development
SubPhylum Urochordata
• Marine animals; some species are solitary, others are colonial.
• Sessile as adults, but motile during the larval stages
• Possess all 5 chordate characteristics as larvae
• Settle head first on
hard substrates and
undergo a dramatic
metamorphosis
(e.g., tail,
notochord, muscle
segments, and nerve
cord disappear)
SubPhylum Urochordata cont.
• Adult body is covered by
an outer envelope or tunic;
composed of fibers of
tunicin embedded in a
mucopolysaccharide matrix
• Tunic encloses a basketlike pharynx, that is
perforated by gill slits
• Tunicates are filter feeders; plankton is trapped in a sheet of mucus
and cilia later direct the food-laden mucus to the stomach
• Water leaves the animal via an excurrent siphon
Chordate Metamerism
• Body segmentation (i.e. metamerism) appears to have evolved in
two lineages of the chordates: the Cephalochordates and the
Vertebrates; probably occurred after divergence from the
Urochordates
• However, segmentation in the chordates does not involve the
coelom
• The cephalochordates and the chordates movement is
accomplished by contraction of muscle fibers that are arranged in
segmented blocks - myotomes
• Presumably, segmentation of muscles developed as an adaptation
for undulatory swimming and rapid burrowing
SubPhylum Cephalochordata
• Exclusively marine animals
• Although they are capable of swimming, they usually are buried in
the sand with only their anterior end being exposed
SubPhylum Cephalochordata cont.
•All chordate characteristics are present throughout their life history
• They are filter feeders: inside of the oral hood is lined with cilia wheel organ
• These cilia, plus cilia in the pharynx help generate a water current
• Water and suspended food particles pass through the oral hood,
equipped with projections called cirri that strain larger particles
• Feed by secreting a mucous net across the gill slits to filter out food
particles that are present in the water.
The End