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COPPERBELT COLLEGE OF EDUCATION
MODULE 3
BIO 261: Diversity, Form and Function of
Organisms
MODULE 3
Copperbelt College of Education
Kitwe- Zambia
Science Department
Copyright
© Copperbelt College of Education 2011
No part of this module may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording or by any
information storage and retrieval system, without permission in writing from the
publisher
Copperbelt College of Education
science Department
p.o box 29382
Kitwe Zambia
Phone:+260212239003
E-mail:[email protected]
Acknowledgements
The COPPER BELT COLLEGE OF EDUCATION SCIENCE DEPARTMENT wishes to thank those
below for their contribution to this BIO 261 MODULE 3:
MUMA A (Mr)
CBUC
CHANGWE P.B (Ms)
CBUC
KAPONGOLO E.L (Mr)
CBUC
BIO 261: Diversity, Form and Function of Organisms
Contents
About this [DOCUMENT TYPE]
1
How this [DOCUMENT TYPE] is structured .................................................................. 1
Course overview
3
Welcome to [Add course title here] [Course sub-title] ..................................................... 3
[Add course title here] [Course sub-title]—is this course for you? .................................. 3
Course outcomes ............................................................................................................... 3
Timeframe ......................................................................................................................... 4
Study skills ........................................................................................................................ 4
Need help? ........................................................................................................................ 6
Assignments ...................................................................................................................... 7
Assessments ...................................................................................................................... 8
Getting around this [DOCUMENT TYPE]
9
Margin icons ..................................................................................................................... 9
Unit 1
11
[Add unit title here]......................................................................................................... 11
Introduction ........................................................................................................... 11
[First topic heading] .............................................................................................. 13
[Second topic heading] .......................................................................................... 15
Unit summary ................................................................................................................. 22
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Unit 2
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Unit 3
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ii
Contents
Unit summary ................................................................................................................. 39
Assignment ..................................................................................................................... 39
Assessment...................................................................................................................... 40
Unit 4
41
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Unit summary ................................................................................................................. 54
Assignment ..................................................................................................................... 54
Assessment...................................................................................................................... 54
BIO 261: Diversity, Form and Function of Organisms
About this Module
Diversity, Form and Function of Organisms Module 3 has been
produced by Copper belt College of Education All modules
produced by Copper belt College of Education are structured in the
same way, as outlined below.
How this Module 3 is structured
The course overview
The course overview gives you a general introduction to the course.
Information contained in the course overview will help you
determine:
 If the course is suitable for you.
 What you will already need to know.
 What you can expect from the course.
 How much time you will need to invest to complete the course.
The overview also provides guidance on:
 Study skills.
 Where to get help.
 Course assignments and assessments.
 Activity icons.
 Units.
We strongly recommend that you read the overview carefully
before starting your study.
The course content
The course is broken down into units. Each unit comprises:
 An introduction to the unit content.
1
About this Module
PHYLUM: CHORDATA
 Unit outcomes.
 New terminology.
 Core content of the unit with a variety of learning activities.
 A unit summary.
 Assignments and/or assessments, as applicable.
Resources
For those interested in learning more on this subject, we provide
you with a list of additional resources at the end of this module;
these may be books, articles or web sites.
Your comments
After completing Module 3 we would appreciate it if you would
take a few moments to give us your feedback on any aspect of this
course. Your feedback might include comments on:
 Course content and structure.
 Course reading materials and resources.
 Course assignments.
 Course assessments.
 Course duration.
 Course support (assigned tutors, technical help, etc.)
Your constructive feedback will help us to improve and enhance
this course.
2
BIO 261: Diversity, Form and Function of Organisms
Course overview
Welcome to Module 3
You will be introduced to higher animals. Higher animals are
animals that bear back bones. In other words, they are known as
vertebrates. Vertebrates comprise fishes, amphibians, reptiles, birds
and mammals. This module is broken down into four units. You
will look at protochordates in unit 1, fishes in unit 2, amphibians
and reptiles in unit 3 then birds and mammals in unit 4.
As a teacher, you may find some ideas familiar, but you are still
encouraged to take up this module seriously. We have made the
concepts in the module as understandable as possible.
Diversity, Form and Function of
Organisms Module 3—is this
course for you?
This course is intended for people who had studied and passed BIO
110 at first year and has also done module 1of this course.
Course outcomes
Upon completion of MODULE 3 you will be able to:
3
Course overview
PHYLUM: CHORDATA
 Identify major morphological and anatomical features of
vertebrates.
Outcomes
including
 Compare and contrast the morphological and anatomical features
of representative taxa among animals.
 Describe the life cycle of important representative taxa among
animals.
 Describe the classification of animal representative taxa.
 Discuss the diversity of vertebrates.
Timeframe
This module is expected to take you a minimum of 80 hours. This
time should be spent on studying the module and doing the
activities.
How long?
Study skills
As an adult learner your approach to learning will be different to
that from your school days: you will choose what you want to
study, you will have professional and/or personal motivation for
doing so and you will most likely be fitting your study activities
around other professional or domestic responsibilities.
Essentially you will be taking control of your learning
environment. As a consequence, you will need to consider
performance issues related to time management, goal setting, stress
management, etc. Perhaps you will also need to reacquaint yourself
in areas such as essay planning, coping with exams and using the
web as a learning resource.
Your most significant considerations will be time and space i.e. the
time you dedicate to your learning and the environment in which
you engage in that learning.
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BIO 261: Diversity, Form and Function of Organisms
We recommend that you take time now—before starting your selfstudy—to familiarize yourself with these issues. There are a
number of excellent resources on the web. A few suggested links
are:
 http://www.how-to-study.com/
The “How to study” web site is dedicated to study skills
resources. You will find links to study preparation (a list of nine
essentials for a good study place), taking notes, strategies for
reading text books, using reference sources, test anxiety.
 http://www.ucc.vt.edu/stdysk/stdyhlp.html
This is the web site of the Virginia Tech, Division of Student
Affairs. You will find links to time scheduling (including a
“where does time go?” link), a study skill checklist, basic
concentration techniques, control of the study environment, note
taking, how to read essays for analysis, memory skills
(“remembering”).
 http://www.howtostudy.org/resources.php
Another “How to study” web site with useful links to time
management, efficient reading, questioning/listening/observing
skills, getting the most out of doing (“hands-on” learning),
memory building, tips for staying motivated, developing a
learning plan.
The above links are our suggestions to start you on your way. At
the time of writing these web links were active. If you want to look
for more go to www.google.com and type “self-study basics”,
“self-study tips”, “self-study skills” or similar.
5
Course overview
PHYLUM: CHORDATA
Need help?
Your course lectures are
Help
Ms P. B. Changwe
0976 876396 or 0969 913824
Mr. E. L. Kapongolo
0979 488913
During Residential School you will have access to the college
library.
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BIO 261: Diversity, Form and Function of Organisms
Assignments
In this course you will be expected to write a total of three
assignments. One assignment will be written after each module. For
example, you will be given an assignment based on module 3.
Assignments
All written assignment to be sent to
The Director,
Copper belt College of Education,
P.O BOX 20382,
KITWE.
You are expected to submit assignments in the order in which the
modules are given to you.
7
Course overview
PHYLUM: CHORDATA
Assessments
At the end of each unit, you will find self-marked activities. These
activities are for your own practice
Assessments
You will also write a Tutor Marked Assessment for this module. It
is important that you do all the self-marked activities and Tutor
Marked Assessment because these will help you check your
progress. We recommend you discuss the contents of the learning
journal with your Tutor.
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BIO 261: Diversity, Form and Function of Organisms
Getting around this module 3
Margin icons
While working through this MODULE 3 you will notice the
frequent use of margin icons. These icons serve to “signpost” a
particular piece of text, a new task or change in activity; they have
been included to help you to find your way around this
MODULE3.
A complete icon set is shown below. We suggest that you
familiarize yourself with the icons and their meaning before
starting your study.
Activity
Assessment
Assignment
Case study
Discussion
Group activity
Help
Note it!
Outcomes
Reading
Reflection
Study skills
Summary
Terminology
Time
Tip
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BIO 261: Diversity, Form and Function of Organisms
Unit 1
PHYLUM: CHORDATA
1.0 Introduction
HELLO! Welcome to unit I of module 3. In this unit you will be
introduced to phylum Chordata.To start with, if I may ask you a
question. What are higher animals? I am sure you will agree with
me that the best term we could use to describe higher animals is the
word chordates. Chordates belong to phylum Chordata. How
would you identify chordates? Of course, by looking at their
general characteristics.
What are the major characteristics of a Chordate? All chordates
have

a notochord: this is a slender rod-like structure on the
dorsal side of an animal for muscle attachment and support.
Notochord may not be present in animals throughout the
life stages.

pharyngeal region: this could be slits or gills of which at
some stage in their life cycle may disappear.

a post anal tail: this is a representation of some structures
forming a chain or a tail which serves for locomotion
especially in lower vertebrates.

a dorsal nerve chord: this leads to a distinct brain. In
other words it forms the central nerves system (CNS).
Besides these four major characteristics of chordates, general body
plan is another aspect. This plan can be cut into various segements;
head, trunk and the tail. Associated with this plan, there is concept
of symmetry known as bilateral symmetry. Meaning that animals
can be cut into halves whereby one half looks like the other from
the head to tail. Now move with me to the issue of classification.
The phylum chordata is classified into subphyla, super classes and
classes. There are five subphyla namely;
 Urochordata or Tunicata
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Unit 1 PHYLUM: CHORDATA

Hermichordata

Cephalochordata

Agnatha

Gnathostomata
Urochordata , Hermichordata and cephalochordata together form
what is called protochordata while Agnatha and Gnathostomata
form another second group known as vertabrata (true vertebrates).
Are we together?
Furthermore, phylum chordata includes the well known vertebrates
and these are fishes, amphibians, reptiles and mammals. The
vertebrates and hagfishes together comprise the taxon craniata.
The remaining Chordates are Tunicates (Urochordata), Lancelets
(Cephalochordata) and possibly some odd extinct groups.
Chordates are well represented in marine, fresh water and terrestrial
habitats from equator to the high northern and southern lattitudes.
Having listed down the sub phyla , you will now be introduced to
each of them in details starting with Urochordata.
Upon completion of this unit you will be able to:
 Describe the characteristics of chordates.
 Identify the structural features of Tunicates, Acorn worms,
Amphioxus, lampreys and hangfish.
Outcomes
 Classify the chordates of representative taxa.
 Discuss the diversity of protochordates.
Acraniata:
Animals without a well developed head region
(skull)
Craniata:
Animals whose head is well developed with
central nerves system (CNS)
Vertebrates:
Animals with a backbone
Terminology
Adding extra rows to the
Table graphicRemoving
rows from the table graphic
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BIO 261: Diversity, Form and Function of Organisms
1.1 Sub phylum: Urochordata
This sub phylum is also known as Tunicata.
1.1.1 Classification of Urochordata
Subphylum: Urochordata
Class: Acidiaceae
Class: Larvaceae
Class: Thaliaceae
There are three classes under phylum Urochordata which in certain
characteristics. However the common characteristics among this
phylum are explained below.
1.1.2 General characteristics for sub phylum Urochordata
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Unit 1 PHYLUM: CHORDATA
Fig 1.1 Structure of common tunicate
Digestive system: a tunicate siphons water in itself and releases it
through excurrent. This is refered to as filter feeding. Filter feeding
is a primitive method of nutrition. Digestion and absorption occurs
in the stomach.
For respiratory system, the heart is responsible for circulating
blood.
Neural system is also functional in tunicates.
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BIO 261: Diversity, Form and Function of Organisms
Reproduction system: tunicates are hermaphrodites meaning that
their sexes are not separated (monoecious). Fertilization occurs
externally. The early stage (larva stage) is motile but as it develops
it changes to its structural appearance. It becomes sessile. The
most prominent feature is the notochord. The notochord gives
support to the entire animal.
Now, move on to sub phylum Hermichordata.
1.2 Sub phylum: Hermichrdata
This is also known as Acorn worm
1.2.1 Classification of sub phylum Hermichordata
Sub phylum Hermichordata consists of two classes
Pterobranchia and Enteropneusta.
Fig 1.2 An acorn worm
represents the internal part
namely;
A. represents the external part B.
The body is divided into proboscis, collar and trunk. Buccal
diverticula is posterior part of proboscis.
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Unit 1 PHYLUM: CHORDATA
1.2.3 Characteristics of subphylum Hermichordata
Digestive system is complete.
Nervous system:
chemoreception
Sensory neurons in proboscis functions in
Respiratory system: respiratory system consists of gill slits
connected to the pharynx with external environment.
A single glomerulus connected to blood vessels may have
excretoryl function and is considered a metanephridium.
Reproductive system: colonies are formed by asexual budding in
Pterobranchs. Asexual reproduction by fragmentation in
Enteropneusta.
Circulatory system is composed of dorsal and ventral vessels and
dorsal heart.
Feeding habits: Many Acorn worms are deposit feeders extracting
the organic components of sediments. Others are suspension
feeders capturing plankton and detritus. The muscular proboscis is
the active part of the animal collecting food in mucous strands on
its surface.
Look at the next sub phylum.
1.3 Subphylum: Cephalochordata
Animals under subphylum Cephalochordata are also refered to as
Amphioxus.
1.3.1 Classification subphylum Cephalochordata
Sub phylum Cephalochordata consists of class leptocardi
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BIO 261: Diversity, Form and Function of Organisms
Fig 1.3 Anatomy of amphioxus
The appearance of Amphioxus is of fish like or larva like. The
posterial region is not fully developed. There is no clear separation
between the head and the trunk. Meanwhile the prominent features
are pharyngeal region which constitutes a bigger region of the trunk
, the gut shows no stomach, gonads develop below the pharynx and
on the dorsal side is the notochord which persist throughout life
span. The notochord is the major supporting structure of the animal
amphioxus. The skin is very thin and does permit exchange of
gases between the environment and animal. There is poor
specialization of organization in amphioxus. Amphioxus tends to
have a segemented body and muscles running from the notochord.
These features are similar to invertebrates. There is poor
cephalization (low development of CNS). However the notochord
is present through out the life cycle.
1.3.3 Characteristics of Amphioxus
Habitat: amphioxus live in marine environmental bottom areas,
burrowing in the sands or mud areas.
Excretory system in the ampioxus is poorly developed. There are
special cells called flame cells responsible for excretion. These
cells remove excretes from internal area to the outside. The
evolutionary features of amphioxus show that they are primitive
chordates closer to the invertebrates.
Feeding: the common method of feeding in amphioxus is filter
feeding methods.
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Unit 1 PHYLUM: CHORDATA
Respiratory system: there is absence of respiratory pigments and
lack of well defined heart.
ACTIVITY 1.1
1. Why are the amphioxus among the chordates and associated with
vertebrates?
…………………………………………………………………….
…………………………………………………………………….
…………………………………………………………………….
2. What is the type of feeding found in tunicates?
.........................................................................................................
........................................................................................................
End of activity
1.4 Sub phylum Agnatha
Agnatha are fish like in appearance. They lack appendages and
jaws.
1.4.1 Classification of Agnatha
Phylum: Chordata
Sub phylum: Agnatha
Class: Ostracoderm
Class: Cyclostomata
Order: Petromyzonitida
Order: Myxinitida
Class: Ostracoderm is extinct and made up of species whose head
had exoskeleton but without developed endoskeleton. They were
marine and filter feeders.
Class: Cyclostomata. ‘Cyclo’ means circular (round) and ‘stoma’
means mouth. Therefore Cyclostomata means round mouth.
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BIO 261: Diversity, Form and Function of Organisms
1.4.2 Characteristics of Agnatha
The body is cylindrical (eel shaped), long and slender.
The notochord is very prominent and persists throughout life span.
Just like all pisces, the heart is two(2) chambered (1 auricle and I
ventricle).
They are poikilotherms (cold blooded).
Unlike other species appendages are not paired, has no rib cage,
has circular mouth and lack jaws.
Class Cyclostomata is divided into two (2) orders myxinitida and
petromyzonitida.
Myxinitida consists of hagfish. Look at the structure of hagfish
below.
Fig 1.4 Atlantic hagfish
The mouth of hagfish tend to be highly terminal. Their gill slits are
any number from one to sixteen(1 - 16). Hagfish are completely
marine.
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Unit 1 PHYLUM: CHORDATA
Petromyzonitida consists of lampreys.
Fig 1.5 Sea Lamprey (Petromyzon marinus)
Lampreys have seven(7) gill slits.The mouth part is funnel shaped
and tend to point downwards. Lampreys are found in both fresh and
marine waters. They live as adults in marine environment hence
have to adjust osmotic potential.
Digestive system: the mouth of agnatha lacks the true jaws but the
cartilage structures are able to piece through the food and get the
food.. the oesophagus is present. There is no well defined stomach
almost no existence. Oesophagus end up with the small interstine
hence they have to keep on feeding.
Circulatory system: there is a ventral heart with two chambers on
the ventral side circulatory system is pumped forward. Oxygenated
blood is first supplied to the brain. On the dorsal side circulatory
system is directed backwards.
Respiratory system: oxygen in waters trapped less efficient, water
enters and comes out through gill slits. It is a primitive way.
Excretory system: Agnatha has pairs of kidneys with a tubular
structure along the system.
Reproductive system: fertilization in agnatha is external and sexes
are separate (dioecious).
1.4.3 Economic importance
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BIO 261: Diversity, Form and Function of Organisms
Lampreys tend to attack other species especially those caught by
fishermen. They lower the value of the catch.
1.4.4 Differences agnatha has from other chordates.
Lacks jaws and paired appendages,
Lacks pelvic girdle,
The ribcage is absent,
The notochord is present throughout its life span.
1.5 Subphylum: Gnathostomata
Gnathostomata is a subphylum of true vertebrates. It consists of
two supper classes: Pisces (fishes) and Tetrapoda.
Supper class pisces consists of the following classes: placoderms
(exitinct), chondrichthyes (sharks and cartilage fish) and
osteichthyes (bony fish). Super class pisces will be discussed in
details inunit 2.
Super class:tetrapoda is associated with four legged animals. It
consists of the following: Amphibian, Reptilia, Aves (birds) and
Mammalia. Super class tetrapoda will be discussed in details in
units 3 and 4 of this module.
Stop for a while and reflect on what you have learnt in unit 1 by
attempting the questions below.
ACTIVITY 1.2
1. Name five subphyla of the phylum chordata
............................................................................................................
............................................................................................................
2. Briefly define the type of symmetry associated with vertebrates
............................................................................................................
............................................................................................................
3. Identify at least three differences between hagfish and lamprey
....................................................................................................................
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Unit 1 PHYLUM: CHORDATA
....................................................................................................................
....................................................................................................................
Unit summary
Summary
In this unit you learned about phylum chordata. It was very
interesting to learn about the characteristics of chordates. In this
unit you also learnt about the five sub phyla under phylum
chordate. Sub phyla: urochordata, hermichordata, cephalochordata
and agnatha were discussed in details while subphylum
gnathostomata was not because it will be covered in the next unit.
Just a quick reminder! All chordates are expected to have four
major characteristics: notochord, pharyngeal region, post anal
metametrical segment and dorsal tubular central nerves system.
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BIO 261: Diversity, Form and Function of Organisms
Unit 2
PISCES (FISHES)
2.0 Introduction
Pisces is a super class. It is also known as fishes. It comprises
classes: chondrichthyes and osteichthyes..
We shall look at chondrichthyes first and then osteichthyes later in
details.
Upon completion of this unit you will be able to:
 Compare and contrast the morphological and anatomical features
between chondrichthyes and osteichthyes.
Outcomes
 Identify the structural features
chondrichthyes and osteichthyes.
representative
taxa
of
 Describe the characteristics of fishes.
Anadromous:
Animals which live as adults in marine water
or environment.
Catadromous:
Animals which spend their time in fresh water
but marine for breeding only.
Oviparous:
A type of development in which the young
hatch from eggs laid outside the mother’s
body
Ovoviviparous:
A type of development in which the young
hatch from eggs incubated inside the mother’s
body
Terminology
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Unit 2 PISCES (FISHES)
2.1 Class: Chondrichthyes
Chondrichthyes are the first true vertebrates. Chondri means have
no true bones but have cartilagous bones as a skeleton system
(cartilage). Ichthyes means fishes. Therefore it means that
chondrichthyes are fishes comprising cartilage bones.
2.1 Classification of chondrichthyes
Sub phylum: Gnathostomata
Class: Chondrichthyes
Sub class: Elasmobranchii
Order: Cladoselanchii (extinct)
Order: Pleuracanthedii (extinct)
Order: Selanchii (Sharks)
Order: Batoidea
Sub class: Holocephali
Order: Chimaerforms
There are two sub classes which have four orders. The first two
orders exist only in fossil records (extinct). Selanchii (order) is the
most popular and is used to represent the sub class elasmobranchii.
The other sub class holocephali has one order chimaerforms.
2.1.1 Characteristics of Chondrichthyes
The skin is fairly tough and covered with placoid scales ( very tiny
pointed scales).The skin is well supplied with mucus glands to
make the fish slippery and move efficiently. Mucus reduces the
resistance of environment when moving.
They are marine but order pleuracanthedii lived in fresh water.
They have ventral mouth (underside of the body) and supported
with sharp teeth. Nostril is not connected in any way to the
pharyngeal of the animal neither to the mouth. They have the
mouth supported by jaws on both upper and lower. The skeletal
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BIO 261: Diversity, Form and Function of Organisms
system is entirely cartilageous. It enables us to consinder it as
evolutionary primitive since the skeleton is cartilageous.
Notochord is present and exists throughout its life cycle. They have
paired fins that are pectorial and pelvic fins. Circulatory system
consists of two chambered heart and a single circulatory system
and moves in one direction of which ventral side is forward while
dorsal side is backward. They are poikilotherm (cold blooded
animals ). They do not require a lot of self generating energy to
maintain and regulate body temperature.
Fig 2.1 Male spiny dogfish shark
Having looked at a picture above, you will agree the fact that
Primitive features associated with chondrichthyes are that they
have no typical oesophagus, the tongue is flat and is found at the
base of the mouth and does not protrude. In addition intestines are
not coiled.
Circulatory system: chondrichtyes have the same plan as
cyclostoma they have two chambered heart. Circulated fluid passes
through the gill slits where it is oxygenated. An improvement is
that water enters the mouth and comes out through the gills slits as
compaired to Agnatha.
Reproductive system: They have separate sexes .This is an
advanced type. Internal fertilization through cloaca is exihibited,
individual offsprings are similar to the parents and breeding takes
place at a particular time and specific areas. Feeding of the young
is separated from the old to avoid feeding competition among the
fishes.
2.1.2 Economic Importance
25
Unit 2 PISCES (FISHES)
Chondrichthyes are food for other animals
They sting and attack the divers
They destroy fishermen’s catches and reducing their values.
2.2 Class: Osteichthyes
This class is also called bony fishes. There is over 20 000 various
fishes. Half vertebrates species are osteichthyes. It is the most
abundant class among the chordata. They exhibit an adaptive
diversity. They have a variety of habitats; open water system, deep
water layers, shore areas and others survive below the water in the
sea.
2.2.1 Characteristics of Osteichthyes
Fig 2.2 Anatomy of a freshwater fish
They consist of a skin and mucous glands. The scales may not be
present in some species. Some have dermal scales (the circular) and
this is the majority of the group. Others have placoid scales but
few.
The mouths of the fishes tend to be terminal with developed jaws.
Depending on the feeding behaviour eg predators (tiger fish, bubble
fish) have very strong jaws.
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BIO 261: Diversity, Form and Function of Organisms
Those which feed on the vegetation and have mouth like filter
feeding, mouths are structured to suit the feeding habits.
Skeletal structure (system) is made of actual (true) bones. It
consists of endoskeleton and exoskeleton on the head of bubble
fish. Notochord is on the dorsal side and persists.
Circulatory system consists of the heart with two chambers.
Respiration system comprises the use of gills. The water enters the
mouth and is released behind the operculum hence the efficience of
absorbing oxygen from water. The gills in some fishes are modified
into a lung eg bubble fish. This is some steps towards evolution.
Others are lung fish whose lungs are to absorb atmospheric air
(oxygen) to withstand the adverse environment .
Concerning body temperature, all fishes are called cold blooded
animals.
The fishes are stream lined to move effectively in water but others
are elongated eg eels. Others the body shape is compressed. The
body shapes vary to suit the habitat.
They have paired appendages. They have swim (air) bladder. This
is an organ used for the movement of the fish to adjust the level in
water.
Gonads in females have well defined shapes which suits the
breeding activity. When you press and the milky stick stuff comes
out then it is a female. The females have a wide and long gonad
and the outside shape of gonads is different from the male one.
The standard length of a fish is considered from mouth to the
posteriol end boadering the caudal fin.
The size of fish varies from species to species and depends on the
age. Fishes do not cease to grow unlike in mammals they continue
growing throughout their life.
There are several ways of describing and identifying fish species;
the shape of caudal fin and covering of scales. Others are covered
with scales on the trunk and tail only. Some are covered the whole
body. Some are spotted.
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Unit 2 PISCES (FISHES)
Fig 2.3 various types of caudal fins
You will also learn that there are evolutionary categories of fishes
and these are sarcrotegii and actinoptergii.
SARCROTEGII
It has long fresh lobed fins. It has cosmoid scales (very small and
thin scales ) and nostrils joined to the buccal cavity.
ACTINOPTERGII
This type of fish has common fins associated with a solid shape.
They are red fins because of the spines present. The number of
spines on dorsal fins suggest the type of fish (help in identifying
fish). This is refered to as dorsal formula.
Have a short break! During this break could you look at the
question below to help you reflect on what you have just read.
ACTIVITY 2.1
In what aspects is the class chondrichthyes more advanced to the
class osteichthyes?
.......................................................................................................
........................................................................................................
........................................................................................................
2. Name two types of skeleton systems found in vertebrates
.........................................................................................................
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BIO 261: Diversity, Form and Function of Organisms
.........................................................................................................
2.3 Some of the Fish Groups from Primitive to highly Evolved/ Advanced
2.3.1 Family: Protoptrinidae
Eg Protopterus anniecters (African lungfish).They are able to gulp
atmospheric oxygen and can live out of water for long periods of
time. Their dorsal fin is jointed together with caudal fin. This type
of fish is found in lower Zambenzi.
2.3.2 Family: Mormyridae
Eg Mormyrus larade, Mormyrus longrastris and Marcusenius
masolepdites
These type of fish have very long extended snout or bottled nose.
They have very tiny scales covering mainly the trunk. They tend to
have darkish colour and have extended caudal region. they are
found in the middle Zambenzi.
2.3.3 family: Anguillidae
Eg Anguilla mossambiquous and Anguilla bincolar
They are eel (shark like structures). There are four species in the
middle Zambezi. In the past they were confined to the middle
Zambezi but now are confined to the lower Zambezi. They are
catadrous (migrate to the sea and spent their adult life there).
2.3.4 Family: Clupeidae
Eg Limnothrissa miodo and stolothrissa tanganicae
Clupeide is locally called kapenta. They are very small fish, found
in open water environment. They feed on minute organisms. They
are identified by a silvery band along the laterial line.
2.3.5 family: Cyprinidae
Eg Barbus paeichii, Labeo altivelis and Cyprinus carpio
They are identified by stream lined body. They lack teeth but have
tubular structure for sucking plankton material. Jaws are poorly
developed. They do not have true stomarch and lack adipose fin.
They are common in lower Zambezi and Luangwa rivers.
2.3 6 Family: Characidae
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Unit 2 PISCES (FISHES)
Eg Bryanus lateralis, bryanus limber and Hydrocynus vittatus
(tiger fish)
They have sharp pointed teeth in the buccal cavity and have scales
apart from the head. They are common in Zambezi river. Hydro
means water and cynus means dog therefore hydrocyrus is one of
the strong preditors. It has forked fin.
2.3.7 Family: Hepsetide
Eg Hepsetus odoe
It is called the Kafue pike and has very nice olive brown colour.
2.3.8.Family: Claride
Eg Clarias gariepinus (barbel fish)
It has a bony cover (exoskeleton). It has projections (spike like
structures) on the body. There are no scales on the trunk.
Henterablandlus longifilis (giant cat fish)
This fish plays a significant role. It is a very good hunter invading
streams. One of its gills is modified into a lung and can survive
many hours out of water provided the place it is in is moist. Hence
traders can transport this fish to far places and remain flesh. It has a
lot of proteins.
2.3.9 Family: Malapterundae
Eg Malepterus electricus
This fish is able to create current. It has an inorganic battery which
it uses to electrocute its prey. The dorsal fin is reduced to vestigial
structure.
2.3.10 Family: Mochokidae
Eg Synodontis sp {zambenzis)
This fish has no scales. It has bony helment (cover), very strong
spins and very short trunk.
2.3.11 Family Cichlidae
Eg Oreochromis andersoni, Oreochromis macrochir, Oreochromis
niloticus, Tilapia rendalli, Tilapia spermnii, Serranochromis
angustica, serranochromis macrocepteris and Haplochromis
giardis.
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BIO 261: Diversity, Form and Function of Organisms
2.3.11.1 Characteristics of Cichlidae
The Cichlidae are referred to as breams.They are covered by the
scales on the trunk, head and gill covers. Dorsal fin is identified
with o black sport (Tilapia spot). It disappears as the fish grows.
Oreochromis andersoni is identified with prominent 3 spots on the
trunk. It is known as ‘three spotted bream’. It is one of the
common fishes in many places in Zambia. It is referred for fish
farming because of its fast growth.
Oreochromis macrochir has a green colour on the head region.it is
called ‘green headed bream’ as a common name. Compared to O.
andersoni growth rate is slow but grows very big hence farmers are
reluctant to grow it.
Oreochromis niloticus does not exist elsewhere but in Nile and lake
Tanganyika and some rivers in West Africa. It is known as ‘Nile
tilapia’. It is identified with Tilapia spot which does not disappear.
Its caudal fin has the lines which cross each other.
Tilapia rendalli has a red covering on the anterior part hence the
name ‘red breasted bream’. It is very famous for feeding on
acquatic miroplanktons in relation to biological control method.
Tilapia spermanii is a very small bream roughly 30cm. it has
greenish bandy running across the trunk.
Seranchromis angustica, Seranchromis macrocepteris and
haplochromis giardi are predators. They have red spots on the
pelvic fin.
2.3.12 Economical importance of bony fish
It provides fishing industry and employment to fishermen and
traders. Fish can be farmed. Fish farming is the fastest food
growing production. It also provides recreation and as an ornament
(aquarium fisheries). Government earns income through licensing.
It is used in biological control methods to control weeds. Species
Haplochromis giardi feeds on snails hence used to control bilhazia.
They feed on mosquito larva and control the spread of malaria.
ACTIVITY 2.2
1. Briefly list three characteristics that make osteichthyes suitable
for life in their habitats …………………………………………..
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Unit 2 PISCES (FISHES)
……………………………………………………………………
……………………………………………………………………
…………………………………………………………………….
Unit summary
Summary
In this unit you learned two classes under superclass pisces or
fishes. Thes two classes are chondrichthyes and osteichthyes.
Condrichthyes are cartilage fishes while osteichthyes are bony
fishes.
Assessment
What are the variations and adaptations of respiratory organs in
super class pisces?
Assessment
32
BIO 261: Diversity, Form and Function of Organisms
Unit 3
AMPHIBIANS AND REPTILES
Introduction
Amphibians are the only living vertebrates that have transition
from water to land in both their organismal development
(ontogeny) and evolutionary history (phylogeny). Some examples
of amphibians are frogs, toads and salamanders. Frogs and toads
belong to the order Anura (have no tails in adults). Salamanders
and newts, on the other hand, belong to the order Urodela (have
tails even in adults). True toads belong to the family Bufonidae.
The members of this family have short legs, stout bodies and thick
skins with permanent warts.
Reptiles are organisms whose body is entirely covered with scales.
Reptiles are found both on land and in water. This means that some
reptiles are found in water for example crocodiles while others are
found on land for example snakes
Upon completion of this unit you will be able to:
 describe the characteristics of amphibians.
 describe the characteristics of reptiles.
Outcomes
 differentiate between amphibians and reptiles.
 state at least two examples of each group.
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Unit 3 AMPHIBIANS AND REPTILES
Terminology
ontogeny:
Organismal development
phylogeny:
Evolutionary history
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
General characteristics of amphibians
Amphibians are organisms that live both in water and on land.
Some of the features that qualify an organism to be an amphibian
are that they have skeleton that is mostly bony. The limbs are
usually four (quadrupedal); the heart has two atria but has only one
ventricle. The skin is smooth, moist and glandular; respiration is
through the skin and in some forms by gills and/or lungs. The
presence of gills and lungs varies among species and by
developmental stage of some species. Amphibians are ectothermic.
The excretory system consists of mesonephric or opisonephric
kidneys. The main nitrogenous waste or excretory product is urea.
The ear has an eardrum or tympanic membrane and stapes for
transmitting sound. The cornea is used for vision while the eyelids
and lachrymal glands protect and wash the eye respectively. The
mouth is usually large with small teeth in the lower and upper jaws.
The nostrils are paired and open into a nasal cavity lined with
olfactory epithelium at anterior (front) part of the mouth.
Amphibians have ten pairs of cranial nerves.
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BIO 261: Diversity, Form and Function of Organisms
Reproduction
Amphibians reproduce by laying eggs. The sexes are separate and
fertilization is mostly external in frogs and toads but internal via a
spermatophore in most salamanders. Eggs hatch into tadpole
having a long tail. In addition the tadpoles have both internal and
external gills. Tadpoles and salamander larvae are carnivorous.
Most larger frogs are solitary except during breeding season.
During the breeding season, most males are very noisy
Protection from prey
Snakes, aquatic birds, turtles and humans prey on adult frogs. Fish
preys on tadpoles. Most adult frogs defend themselves by feigning
death (they pretend that they are dead). When disturbed along the
margin of a pond, a frog usually remains quite still. If they sense
danger, it jumps into the grass cover. In addition, when held, a frog
puts its captor off guard by ceasing to struggle. Then it leaps
suddenly while releasing urine. In most amphibians, the ability to
leap as well as use of poison glands is best method of protection
Activity 3.1
1. In which habitat are amphibians mostly found?
………………………………………………………………
………………………………………………………………
2. State at least four characteristics of amphibians.
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
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Unit 3 AMPHIBIANS AND REPTILES
………………………………………………………………
………………………………………………………………
………………………………………………………………
……………………………………………………………..
3. How do amphibians reproduce?
………………………………………………………………
………………………………………………………………
4. List three types o amphibians.
………………………………………………………………
………………………………………………………………
………………………………………………………………
5. Explain how amphibians protect themselves from predators.
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BIO 261: Diversity, Form and Function of Organisms
General characteristics of Reptiles
Reptiles are organisms with bodies that are covered with epidermal
scales and sometimes bony dermal scales, integument with few
glands. Reptiles have two pairs of limbs with five toes. The limbs
are adapted for climbing, running or paddling. However, in reptiles
such as snakes and some lizards, the limbs are vestigial. Apart from
snakes, the skeleton of the rest of the reptiles is ossified and also
have ribs. The skull has one occipital condyle. Respiration in
reptiles is mainly through lungs which have a large surface area.
However some reptiles use the cloaca, pharynx or skin for
respiration. The circulatory system is divided into systemic and
pulmonary circulation. Reptiles are ectothermic. The kidneys are
metanephric and are paired. The main excretory product is uric
acid.
They have a nervous system with optic lobes on the dorsal side of the
brain. There are 12 pairs of cranial nerves. The sexes are separate and
fertilization is internal. The eggs are covered with calcareous or leathery
shells. Extraembronic membranes (amnion, chorion, yolksac and
allantois) are present during embryonic life
Activity 3.2
1. In which habitat are reptiles mostly found?
………………………………………………………………
………………………………………………………………
2. State at least four characteristics of reptiles.
………………………………………………………………
………………………………………………………………
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Unit 3 AMPHIBIANS AND REPTILES
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
……………………………………………………………..
3. How do reptiles reproduce?
………………………………………………………………
………………………………………………………………
Tortoises and turtles
Tortoises and turtles are enclosed in shells consisting of a dorsal carapace
and a ventral plastron (breastplate). The shell is fused to the thoracic
vertebrae and ribs. The shell protects the head and appendages (limbs).the
limbs can be retracted inside.
Turtles do not breathe by expanding their chest because of the shell;
instead, they use abdominal muscles. Turtles have poor vision and are
mute. However, they have good sense of smell color vision.
Reproduction is by laying eggs. Fertilization is internal. The eggs are
buried in the ground. Nest temperature determines the sex of the
hatchlings. In turtles low temperatures produce males while high
temperatures produce females.
Lizards and snakes
These belong to the order Squamata. Lizards belong to suborder
Sauria. Lizards are a diverse group some of which are terrestrial,
burrowing, arboreal and aerial. They have movable eyelids. Examples of
lizards are geckos, iguanas, monitors and chameleons. Lizards are
ectothermic and they have an external ear. However hearing is not very
important in most lizards except for geckos because the males are
strongly vocal to announce their territory
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BIO 261: Diversity, Form and Function of Organisms
Snakes belong to suborder Serpentes. Snakes do not have limbs.
Snakes’ eyes are permanently covered
Crocodiles and alligators
[Add topic text here]
Unit summary
In this unit you learned [Add summary text here - you may wish to use
the unit outcomes to write this text]
Summary
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Assignment
[Add assignment text here]
Assignment
[Continue your body text here]
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Unit 3 AMPHIBIANS AND REPTILES
Assessment
[Add assessment text here]
Assessment
[Continue your body text here]
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BIO 261: Diversity, Form and Function of Organisms
Unit 4
AVES (BIRDS) AND MAMMALS
Introduction
Birds are organisms whose bodies are covered by feathers. They
have beaks and scales on their feet. Birds reproduce by laying eggs.
There are different types of bird some birds are nocturnal eg. The
owl while others are not
Upon completion of this unit you will be able to:
 [verb] [complete the sentence].
 [verb] [complete the sentence].
Outcomes
 [verb] [complete the sentence].
 Mention at least four mammalian orders.
 [verb] [complete the sentence].
 [verb] [complete the sentence].
Terminology
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
[Term]:
[Term description]
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Unit 4
AVES (BIRDS) AND MAMMALS
General characteristics of aves (birds)
The aves or simply birds have very interesting characteristics or features
that are unique to them. I am very sure that you are able to distinguish
birds from animals like amphibians and reptiles that you learnt in unit 1
and unit 2 respectively. So can you write at least two features that
distinguish birds from other animals?
1) ……………………………………………………………………
……………………………………………………………………
…………………………………………………………………….
2) ……………………………………………………………………
……………………………………………………………………
……………………………………………………………………
Okay, that’s good! Now let us look at the features or characteristics of
birds in detail. Generally birds have four divisions or parts. The four parts
are head, neck, trunk and tail. The neck is disproportionately long for
balancing and for food gathering. They have two pairs of limbs namely
forelimbs (front limbs) and posterior limbs (hind limbs). The forelimbs
are usually modified for flying while the posterior limbs are adapted for
perching, walking and swimming. The body is covered with feathers and
leg scales. Aves do not sweat glands, oil or green gland at the base of tail.
Birds have a skeleton which is ossified with air cavities. The front part of
the head has a beak but there are no teeth. The nervous system is well
developed. In addition to the nervous system, birds also have a
circulatory system. The heart has four chambers. This is not the first time
you are coming across a four chambered heart. Can you name another
organism that has a four chambered heart? Did you say human being?
Very good, that’s correct! A human being has a four chambered heart.
Aves are endothermic organisms. Do have any idea what that means?
Well, it simply means that birds are warmblooded.
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BIO 261: Diversity, Form and Function of Organisms
Feathers
These possess remarkable toughness and tensile strength. Most
feathers are contour feathers. Each contour feather consists of a
hollow quill or calamus and shaft or rachis. The shaft has
numerous barbs. Barbs are arranged in closely parallel fashion and
spread diagonally outward from both sides of the central shaft to
form a flat, expansive
DIAGRAM OF CONTOUR FEATHER ON PG 380
Fig 4.0
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Unit 4
AVES (BIRDS) AND MAMMALS
Classification
Birds are divided into two main groups. Guess what! The groups
are based on whether the birds are able to fly or not. Aves that are
able to fly belong to the group Neognathae. This group of birds
escapes from predators by simply flying away. The ones that are
not able to fly belong to the group Paleognathae. Can you guess
how such birds escape from predators? Did you say by this flying?
Of course not! Try again. Did you say by hiding? OOh! You can do
better than that. Ok, I will tell you. It’s by running very fast away
from predators. Examples of flightless birds are Ostriches and
Kiwis.
Skeleton
A major requirement for flight is a light skeleton. The bones of
flying birds are therefore light, delicate and have air cavities. The
bones are said to be pneumatized. Pneumatized bones are
nevertheless strong. In addition the bird’s skull is built lightly and
fused in one piece.
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BIO 261: Diversity, Form and Function of Organisms
Digestive system
Birds do not have teeth hence foods that require grinding are
reduced in the gizzard. Salivary glands are poorly developed and
mainly secrete mucus for lubricating food and the tongue. The
pharynx
is short and leads into the relatively long muscular
esophagus which extends into the stomach. A n enlargement called
the crop is found at the end of the esophagus and serves as a food
storage chamber. In birds like pigeons, parrots and doves the crop
produces a lipid and protein rich milk.
In order to grind food, birds swallow gritty objects or pebbles
which lodge in the gizzard. The cloaca is found at the terminal end
of the digestive system. It serves as both reproductive part as well
as for taking out waste matter.
Beaks of birds are adapted to specialized food habits. Some beaks
are chisel shaped while others are sharp and pointed. The following
diagrams show different beaks of variety of adaptations.
Fig 4.2
Reproductive System
Males birds do not have a penis but only have testes and these
appear very tiny and have a bean shape. During the mating or the
breeding season, the testes however enlarge. During copulation the
male touches his cloaca against that of a female. The sperms are
released into the female cloaca. These sperms remain alive for
main days after a single mating.
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Unit 4
AVES (BIRDS) AND MAMMALS
Females only have one ovary, the left ovary and oviduct. Female
birds tend to lose the right ovary, that is the ovary and oviduct on
the right side become vestigial structures. Now this is interesting!
What reason can you give for this kind of adaptation in females?
The ovary releases the eggs which pass down the oviduct. At this
point fertilization takes place. The fertilized egg continues moving
down the oviduct. Special glands secrete albumin, or egg white,
which is added to the egg. Later on in the oviduct shell membrane,
shell and shell pigments are secreted around the egg.
Diagram of female reproductive system
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BIO 261: Diversity, Form and Function of Organisms
Care for young
All birds lay eggs that must be incubated by one or both parents.
Most birds build some form of nest in which to rear their young
ones. Some young ones hatch naked, blind and are unable to walk.
Such are referred to as altricial birds. Others, however, are able to
walk and see soon after hatching. In addition they are covered with
down feathers. Such birds are referred to as precocial birds.
Fig 4.4
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Unit 4
AVES (BIRDS) AND MAMMALS
Activity 4.1
1. State at least four characteristics of aves (birds).
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
……………………………………………………………..
2. How do birds reproduce?
………………………………………………………………
………………………………………………………………
Origin and Evolution of mammals
Present day mammals are descendent of organisms of the
Paleozoic era particularly the synapsids. Synapsids have openings
in the temporal region of the skull associated with attachment of
mandibular muscles. The earliest synapsids were pelycosaurs
(which were herbivorous) and therapsids which were carnivorous).
Pelycosaurs diversified extensively and evolved changes in jaws,
teeth and body form. Evolution continued and gave rise cynodonts
from which modern mammals come from.
General characteristics of mammals
Modern living mammals differ from each other on the basis of
reproduction. There are three types or patterns of reproduction
48
BIO 261: Diversity, Form and Function of Organisms
among mammals and classification is based on the type of
reproduction. Monotremes are egg-laying mammals, marsupials
are pouched mammals and placental mammals. There are at least
29 recognized placental mammalian orders. In this module, only
seven orders will be discussed. The orders are Primates, Chiroptera,
Rodentia,
Proboscidea,
Lagomorpha,
Perissodactyla
and
Artiodactyla. We will look at each of these orders later in this unit.
We will also briefly look at marsupials and monotremes.
This group of animals is a very interesting one. Can you think of
the reason why it’s interesting? Of course one of the reasons is that
that is where we, as human beings, belong! Now that makes it even
easier for you. What are some of the features of a human being?
What about features of a cow? You know cattle are mammals too. I
suppose stating that having hair or fur was amongst the many
things that you thought about. You are absolutely correct! Humans
have hairs on their skin while cattle have fur. Perhaps the most
interesting feature is that all mammals have breasts or mammary
glands.
Activity 4.
1. Which organism are ancestors of mammals?
……………………………………………………………………..
2. Mention the three types of modern mammals
a) ……………………………………………………………………
b) ……………………………………………………………………
c) ……………………………………………………………………
3. List at least five orders found in class mammalian.
a) ……………………………………………………………………
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Unit 4
AVES (BIRDS) AND MAMMALS
b) ……………………………………………………………………
c) ……………………………………………………………………
d) ……………………………………………………………………
e) ……………………………………………………………………
The body of most mammals is mostly covered with fur. Of course
humans and pigs are an exception in that their skin is covered with
hairs. Depending on the type of mammal integument glands could
be either sweat, scent sebaceous or mammary glands. The skull has
two occipital condyles. The nasal cavity is present too. This is true
because animals breathe through their nostrils or simply through he
nose. The outer ear is fleshy while the middle ear has three small
bones and most of them have seven cervical vertebrae. In addition
the pelvic bones are fused. Some mammals like human beings
which have two sets of teeth are said to be diphyodont. The milk
teeth are replaced by permanent teeth. Most have mammals have
heterodont teeth which vary in structure and function. The eyelids
are movable
The circulatory system consists of four chambered heart with a
persistent left aortic arch. Respiratory system composed of lungs
with alveoli. There is muscular diaphragm for gaseous exchange.
The excretory system consisting of metanephric kidneys and
ureters that usually opens into a bladder. The brain is highly
developed and 12 pairs of cranial nerves are present. Some
mammals are endothermic while others are homeothermic.
Mammals have separate sexes and fertilization is internal. The
young ones are fed on milk
Activity 4.2
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BIO 261: Diversity, Form and Function of Organisms
1.
In which habitat are mammals mostly found?
………………………………………………………………
………………………………………………………………
2. State at least four characteristics of mammals.
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
………………………………………………………………
……………………………………………………………..
3. How do mammals reproduce?
………………………………………………………………
………………………………………………………………
Care for the young
All mammals have mammary glands. Therefore one of the ways in
which most mammals care for the young ones is by feeding them
on milk.
Marsupials
These mammals have pouches. They do not have a true placenta.
They have a special type of placenta called yolk sac placenta.
Embryos of marsupials are encapsulated by shell membranes. After
hatching the embryos do not in plant in the uterus. Instead they
make shallow depressions in the uterine wall in which they lie and
absorb nutrients. Gestation period is very brief but lactation period
is prolonged. An example of a marsupial is a kangaroo
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Unit 4
AVES (BIRDS) AND MAMMALS
Monotremes
These are mammals that lay eggs. An example is the duck-billed
platypus. The gestation period is about 10-12 days. After hatching,
the young feed on milk from the mother. However, the young do
not suck the milk instead they lap the milk secreted onto the
mother’s belly. Why do think the young do not suck? Well, it is
because monotremes have no nipples!
Order: Primates
Primates have a large cerebral cortex and because of this primates
come first in brain development in the animal kingdom. Most
species have large eyes in two occipital condyles.
Order: Chiroptera
These are mammals which are able to fly because their fore limbs
are modified into wings. An example of this order are bats. Bats
are mostly nocturnal, that is they are active at twilight and at
night. Bats navigate by echolocation. They therefore are able to fly
quickly, while avoiding obstacles, even in absolute darkness. In
addition bats are able to locate and catch insects with precision as
well as finding their way deep into the caves. When in flight, a bat
emits short impulses 5 to 10 m/sec in duration
Order: Rodentia
These are mammals which are able to fly because their fore limbs
are modified into wings.
Order: Proboscidea
These are mammals which are able to fly because their fore limbs
are modified into wings.
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BIO 261: Diversity, Form and Function of Organisms
Order: Lagomorpha
These are mammals which are able to fly because their fore limbs
are modified into wings.
Order: Perissodactyla
Order: Artiodactyla
Order: Primates
Glands
Mammals have the greatest variety of integumentary glands. There
are four classes of glands namely sweat, scent, sebaceous and
mammary glands.
Sweat glands are tubular, highly coiled glands that occur over
much of the body surface. There two kinds of sweat glands: eccrine
and apocrine. Eccrine glands secrete a watery fluid that cools the
skin when it evaporates. Apocrine glands are larger than eccrine
glands and have longer and more convoluted ducts. Apocrine
glands always open into a hair follicle. In addition apocrine glands
develop near sexual puberty and are restricted (in humans) to the
arm pits (axillae), mons pubis (pubic area), breasts, prepuce,
scrotum and external auditory canals.
Sebaceous glands- are associated with hair follicles. These glands
produce sebum into the hair follicle.
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Unit 4
AVES (BIRDS) AND MAMMALS
Unit summary
Summary
In this unit you learned aves and mammals. You learned that birds
reproduce by laying eggs. Females only have one ovary, the left ovary.
Mammals are of three types and these are monotremes, marsupials and
placental mammals.
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Assignment
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Assignment
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Assessment
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Assessment
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BIO 261: Diversity, Form and Function of Organisms
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Answers to activities in this module
Activity 1.1
1. presence of the notochord,
Presence of pharyngeal region,
Presence of central nerves system though poorly developed and
Cephalization though poorly developed.
2. Filter feeding.
Activity 1.2
1. Urochordata, Hermichordata, Cephalochodata, Agnatha and
Gnathostomata.
2. Bilateral symmetry
3. lampreys have seven gill slits while hagfish have varying
number between one and sixteen
The mouth of lampreys tends to point downwards while that of
hagfish is highly terminal.
Lampreys are fresh and marine water living while hagfish are
completely marine.
Activity 2.1
1. Chodrichthyes exhibit internal fertilization,
At birth individual offsprings are similar to the adults
Parents provide parental care,
Young ones feed separetly on special food.
2. cartilage and
True bones
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Unit 4
AVES (BIRDS) AND MAMMALS
Activity 2.2
Their skin contain mucus glands for little resistance with media
Their bodies are streamlined to enable easy penetration and
locomotion
They have a swim bladder that aids with bouyance.
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