ANIMAL BIODIVERSITY

BIODIVERSITY

Biological Diversity

Can be observed at 3 levels:– Genetic diversity

– Species diversity

– Ecosystem diversity

SPECIES DIVERSITY

Diversity of organisms on earth

ECOSYSTEM DIVERSITY

• Diversity in habitat, biota community, ecological processes in the terrestrial, marine and other aquatic systems

IMPORTANCE OF BIODIVERSITY

• Economic importance • Food• Environmental stability• Our heritage• Scientific, educational and recreational

value• Biological safety

ANIMAL CHARACTERISTICS       Eukariot        Multicellular        No cell wall        Can be differentiated through feeding

methods        Digest their food        Respire        React to stimulus        Able to move        Excrete        Transport food in the body

Eucaryotic Cell

ANIMALS: How many species exist?

• A few years back: – estimate 2 – 8 million

– 1.4 million known to science

• Now:– Estimate 30 – 50 million species

TRADITIONALLY CAN BE GROUPED BASED ON ON CHARACTERISTICS ASSOCIATED

WITH THEIR EMBRYONIC DEVELOPMENT

• Number of layers of primary tissue - diploblastic, triploblastic

• Is there a coelom formed and how was it formed;

• Cell alignment during cleavage;• What is formed from the blastopore; and• Body symmetry

Animal DevelopmentExample : sea urchin

• Development of the blastula is the earliest development stage of the embryo

• Firstly the unicellular zygote divides into two in a process called cleavage

8-cell stage

Animal Development (cont.)

• Both cells continue to divide until a 1-cell layer hollow ball called blastula is formed

• The space in the blastula is filled with fluid

• For sea urchin, formation of the blastula completes 10 hours after fertilization.

Animal Development (cont.)

• External layer of blastula folds inward until a 2-layer structure called gastrula is formed

• External cell layer is called ectoderm and the inside called endoderm.

• The mesoderm is formed in between

Animal Development (cont.)

• Ectoderm develops to form skin and nerve tissues;

• Endoderm forms the digestive system; • Mesoderm forms the muscle,

reproductive organs and circulatory system

• For deuterosomes, the mesoderm is formed from a clump of cells detached from the endoderm

Animal Body CavityAcoelomate – no cavityPseudocoelomate – not true cavity ie. false cavity

Coelomate – true body cavity

Blue – ectoderm, Red – mesoderm, Yellow - endoderm

Animal Body Cavity - Acoelom

• Example – flat worm;• Body made up of 3 layers(tripoblastik); • Possess digestive tract but no body cavity;• First animal class where muscle and other organs

evolved from the mesoderm;• Organs buried in mesodermal tissue; and• Water and digested food move along body through

absorption.

Internal parts of a Planaria (flat worm)

Animal Body Cavity - Pseudocoelom

• Example – nematode;• Size: 400m to 5 mm;• One of the most abundant animal on earth;• Fluid-filled pseudocoelom forms between

endoderm and mesoderm• Cavity not lined with mesothelium (as in

eucoelom)• Enable animals to move more effectively, esp. in

terms of muscle function;• Organs buried in mesodermal tissue; and• Another eg.: Phylum Rotifera

A nematode

Coelom

• Body cavity covers the entire vertebral column;

• Cavity lined with mesothelium

• Divides body into inner and outer tubes;

• During development, coelom divides into various components.

EXAMPLES OF COELOM COMPONENTS

• Fish– Pericardium (around the heart)– Pleuroperitonium (around other viscera)

• Mammals– Pericardium (around the heart)– Pleuron (around the lungs)– Peritonium (around other viscera)

ANIMAL BODY FORMS AND THEIR ADAPTATION

What is meant by body symmetry?

Symmetry refers to the balance of an animal body

Kinds of symmetry:

Asymmetry

• Eg. sponge (Filum Porifera)

• Normally sessile animals

• No distinct symmetry

Kinds of symmetry (cont.)

Radial Symmetry

• Eg. Hydra (Phylum Coelentrata);• Can be divided in any plane;• Radial symmetry is an adaptation by Hydra

to enable it to detect and catch prey from any angle.

Cross section of a Hydra

Kinds of symmetry:

Bilateral Symmetry• Left and right sections mirror image of the

other;• Anterior section different from posterior• Dorsal area different from ventral• All animals with bilateral symmetry possess a

body cavity where all the organs are located;• Due to the presence of body cavity, animals

can grow to a bigger size and are able to move and feed effectively;

• Without body cavity animals will have to depend on absorption for food.

Flat Worm- external features

A    dorsal B    dorsal and ventral 1    head2    anterior 3    posterior 4    eye spot 5    Sensory lobe 6    dorsal 7    Mouth8    Pharynx (extended during feeding) 9    Pharynx opening10   Genitalopeningl 11   Ciliated ventral surface.       

Internal sections of a Planaria

Example of a planaria Dugesia sp

THE ANIMAL KINGDOM

Colonial Protist

Parazoa Metazoa

Porifera Others

Early division of animal kingdom

Animal Groups

MolluscaAnnelidaArthropoda

EchinodermataChordata

      

      

      

      

      

      

      

                                                                        

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ANIMAL KINGDOM

Subkingdom Invertebrata– Larger in numbers

– Many without skeleton

– Some only with exoskeleton

– A few with endoskeleton

Subkingdom Vertebrata– Possess a notochord

– During adult stage notochord replaced with vertebra

– Brain contained in a cranium

ANIMAL KINGDOM

Invertebrata– Protozoa

– Porifera

– Coelentrata

– Annelida

– Mollusca

– Platyhelminthes

– Nematoda

– Arthropoda

– Echinodermata

Vertebrata– Fish

– Amphibia

– Reptilia

– Aves

– Mammalia

PHYLUM PROTOZOA

• Smallest animals• Now placed in Kingdom Protista• Body made up of one cell• Free-living or parasitic• Parasitic protozoa cause illness such as malaria,

dysentery and others;• Found in freshwater or marine environment• Some marine species excrete skin made of calcium

Free-living Protozoa:

Paramaecium – freshwater

Some forms of Foraminifera –Marine protozoa with external shell

Protozoa - Euglena

Euglena can change form easily

Hundreds of Euglena in a single drop of water

PARASITIC PROTOZOA

Species IllnessTrypanosoma brucei gambiensis chronic sleeping sickness

Plasmodium malariae MalariaEntamoeba Amoebic dysentery

PHYLUM PORIFERA

Basic Morfology of Sponge

PHYLUM PORIFERA – SOME CHARACTERISTICS

• Represents all sp of sponges (about 5000 sp)• Only representative of Parazoa (animals without true

tissue)• Almost all –radial symmetry• Almost all made up of 3-layered cell• Outer layer made up of flattened cells with numerous

pores;

• Middle layer contains mobile cells (amoebocytes or archaeocytes) and skeletel cells

– skeletal cells in form of spogin (flexible protein) or mineral containing particles;

– amoebacytes: collect food vacoules from coanocytes, digest food and send to cells that require it.

• Inner layer made completely of cells called choanocytes

•Do not have digestive tract, nerve cells or muscle cells.

PORIFERA CHARACTERISTICS (cont)

CLASSIFICATION OF PORIFERA

At one time, a diagnostic feature of the Porifera was the presence of spicules

As a result, certain fossil groups whose organization was consistent with that of living sponges were not placed within the phylum Porifera. These are groups with a solid calcareous skeleton

4 Different Forms of Spicules

Megascleres – large, can be seen with naked eyes

Microscleres - small

SEM of Spicules

CLASSES IN PHYLUM PORIFERA

• Calcarea

• Demospongia

• Hexactinellida

CLASSIFICATION OF SPONGES

Archaeocyatha – no living representative

Stromatoporoids

Choanoflagellates

Class Calcispongiae (Calcarea)• Spicules formed from

calcium carbonate;• Spicules in the form of

needles or with 3 or 4 branches;

• Spicules not hollow (stronger);

• All marine members;• Most in shallow waters. Leucosolenia sp

CLASS DEMOSPONGIAE• Abour 90% sponges in

this class;• Spicules formed from

spongin, silica or both;• Can grow to large size;• Found in all tropical and

sub-tropical waters; and• One FW family

Bath sponge

CLASS HEXACTINELLIDA• Spicules formed from silica

(sometimes called glass sponge);

• Spicules joined at 90o angle – make it seem like artificial sponge;

• Spicules with 6 branches;

• Almost all extinct

Aphrocallistes sp

Three groupings of sponges based on water circulation system

• Asconoid (eg Leucosolenia sp)

• Syconoid (eg. Scypha)

• Leuconoid

Groupings based on water circulation system

TYPICAL SPONGE FEEDING

- Water flowing through sponges provides food and oxygen, as well as a means for waste removal

-Can filter up to 20,000 times its volume in a single 24 hour period

- Feed on bacteria – can trap up to 90% of bacteria in water

- Some sponges harbour symbionts such as green algae, dinoflagellates, or cyanobacteria, from which they also derive nutrients.

CARNIVOROUS SPONGE

• Family Cladorhizidae • Feed by capturing and digesting whole animals. • Use spicules to capture• Prey – small crustaceans