Question

Explain about the animals with jointed legs that you have studied.

Answer 1

Arthropoda is the largest phylum of the animal kingdom. They are bilaterally symmetrical, triploblastic and coelomate animals.

• The body is divisible into head, thorax and abdomen. Each thorasic segment bears paired jointed legs.
• Exoskeleton is made of chitin and is shed periodically as the animal grows. The casting off and regrowing of exoskeleton is called moulting.
• Body cavity is filled with haemolymph (blood). The blood does not flow in blood vessels and circulates throughout the body (open circulatory system).
• Respiration is through body surface, gills or tracheae (air tubes).
• Excretion occurs by malphigian tubules or green glands. Sexes are separate.

Example: Prawn, Crab, Cockroach, Millipede, Centipedes, Spider, Scorpion