Question

Two out of every three known animal species are arthropods. Describe the general body plan of an arthropod, give an example of an organism belonging to each of the three major groups (Cheliceriformes, Myriapoda, and Pancrustacea); and explain why the arthropods have been so successful.

Answer 1

Ans.Arthropoda is the largest phylum of animal kingdom with about 9,00,000 species over two - third ( 60-70%) of all named species on earth are arthropods .

General body plan:

it is much hetrogenous group including crab, mosquito, honeybee, locust, butterfly, scorpion, prawn etc

: Bilateral symmetrical

: Segmented body

: These are coelomates as true coelom is present .

: Body is covered by hard, water- proof exoskeleton made up of chitin . this chitin exoskeleton is one of the reason of successful existance of Arthropods on the earth . It provide protection & support to the body & internal organs.it also prevent the loss of water due to evoparation thus live in dry environment.

Body divide into: Head ,thorax and abdomen .( Segmented body). , Joint appendages ( Arthros- joint, poda- appendages ) .

eg. Group cheliceriformes: horse shoe crabs, spider ,ticks ,scorpion etc.

Myriapoda: centipedes, millipedes, pauropods , symphylans etc.

pancrustacea: Hexapods & crustaceans .