Animal Kingdom
👇 Download Handwritting Notes 👇
TAXONOMY :
Taxonomy is the branch of science which deals the study of nomenclature, classification and principles
of classification. Taxonomy word was given by "Candolle" (Taxis - arrangements. Nomia-distribution)
Aristotle :- He is known as the "father of zoology". (Book : Historia Animalium)
He is also known as the father of ancient taxonomy. He classified animals into two groups on the basis of the
colour of blood.
(1) Anaima - Those animals which don't have red blood or in which RBC are absent. e.g. Invertebrates like
Sponges, Cnidaria, Mollusca, Arthropoda, Echinodermata.
(2) Enaima :- These animals have red blood. This group includes all vertebrates and it has been further
divided into two sub groups.
(a) Vivipara :- It includes animals which give birth to young-ones. e.g. Mammals.
(b) Ovipara :- It includes animals which lay eggs. e.g. Pisces, Amphibians, Reptiles, Aves etc
IMPORTANT PHYLA
1. Protozoa (Included in kingdom - Protista) - Amoeba , Paramoecium etc.
2. Porifera (Kingom - Animalia) - Sponges (Leucosolenia, Sycon)
3. Coelenterata/Cnidaria - Hydra, Jellyfish etc.
4. Ctenophora (minor phylum) - Pleurobrachia, Ctenoplana
5. Platyhelminthes - Flat worms (eg : Tape worm)
6. Nemathelminthes/Aschelminthes - Round worm (eg : Ascaris )
7. Annelida - Earthworm , Leech etc.
8. Arthropoda - Insects , Scorpion , Fly etc.
9. Mollusca - Snail, Pila, Octopus etc.
10. Echinodermata - Star fishes
11. Hemichordata - Balanoglossus
12. Chordata - Fish, Snake, Birds, Monkey etc
BASIS OF CLASSIFICATION
1. Level of body organisation :-
Protoplasmic level
Cellular level
Tissue level
Organ level
Organ system level
Symmetry :
(a) Asymmetry :- When any plane that passes through the centre does not divide the body of animals into
two equal halves.
e.g : most of the sponges are asymmetrical.
(b) Radial symmetry : When any plane passing through the central axis of the body divide the animal into
two identical halves.
e.g : Coelenterates, Ctenophores and Echinoderms (adult)
(c) Bilateral symmetry : When the body can be divided into identical left & right halves in only one plane.
e.g : Platyhelminthes to Chordates.
Radial Symmetry
Bilateral Symmetry
Germinal layers :-
(a) Diploblastic – Animals in which the cells are arragned in two embryonic layers ectoderm and endo-
derm with an interveining undifferentiated mesoglea e.g. Coelenterates and Ctenophores.
(b) Triploblastic – Those animals in which the developing embryo has a third germinal layer–Mesoderm
in between the ectoderm and endoderm e.g. Platyhelminthes to Chordates.
Body Cavity or Coelom :- Presence or absence of a cavity between the body wall and gut wall is very
important in classification.
(a) Acoelomates – Animals in which the body cavity is absent
e.g. Porifera, Coelenterata, Ctennophora, Platyhelminthes
(b) Pseudocoelomates – In same animals body cavity is not lined by mesoderm, instead, the mesoderm is
present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called
pseudocoelom.
e.g. Aschelminthes.
(c) Coelomates – Animals possessing coelom i.e. the body cavity which is lined by mesoderm on all sides
* On the basis of embryonic development, the coelom is of two types
(i) Schizocoel – Coelom formed by splitting of a mesodermal mass
e.g. Annelida, Arthropoda, Mollusca.
(ii) Enterocoel – Coelom formed by fusion of gut pouches during embryonic stage
e.g. Echinodermata, Hemichordata and Chordata
Body plan :
(a) Cell-aggregate type e.g. Sponges
(b) Blind Sac type :- Animals in which digestive system is incomplete, it has only single opening to the
outside of the body that serves as both mouth and anus.
e.g. Coelenterates to Platyhelminthes
(c) Tube-within-tube type :- Found in those animals having complete digestive tract i.e. with separate
openings mouth and anus
eg - nemathelmanthes to chordates
Segmentation :-
(a) Pseudometameric– e.g. Tapeworms
(b) Metameric – In Annelids, Arthropods and Chordates.
In these animals, the body is externally and internally divided into segments with a serial repetition of
atleast some organs, this is called metameric segmentation and the phenomenon is known as
Metamerism.
Notochord :- It is a mesodermally derived rod-like structure formed on the dorsal side during embryonic
development in some animals.
(a) Non-chordates – Animals without notochord e.g. Porifera to Hemichordata
(b) Chordates – Animals with notochord. eg. Chordata
Circulatory system :-
(a) Open type – In which the blood is pumped out of heart and the cells & tissues are directly bathed in it.
e.g. Arthropods, Molluscs, Echinoderms, Hemichordates and some lower Chordates like tunicates
(b) Closed type – In which the blood is circulated through a series of vessels of varying diameters i.e.
arteries, veins and blood capillaries
e.g. Annelids, Cephalopod molluscs, Vertebrates etc.
. Embryonic development : On the basis of fate of blastopore, animals can be divided into two categories :
(a) Protostomiates : Animals in which mouth is formed first (Blastopore ® Mouth)
e.g. Platyhelminthes to Mollusca
(b) Deuterostomiate : Animals in which anus is formed earlier than mouth (Blastopore ® Anus)
e.g. Echinoderms, Hemichordates and Chordates.
0 Comments