Lecture 1&2_ Intro , Protozoa , Por if Era
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Transcript of Lecture 1&2_ Intro , Protozoa , Por if Era
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
Slide 2 of 19
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