Habit and habitat: This phylum is. the largest.in animal kingdom. About 60-65% of the known animals belong to this phylum. They are - universally distributed and are adapted to live in almost all types of environments.
Many species are either ecto or endoparasite. They are terrestrial or aquatic. Many of them are capable of flying like cockroach, butterflies,
Bagdaprawn, king crab, spider etc are members of this phylum.
a. Body is divisible into different regions, namely head, thorax and abdomen of cephalothorax and abdomen or head and trunk. Appendages of the animals of this phylum are jointed or formed by many segments.
b. Body is covered by cuticle enriched with chitin.
d. In the head there is a pair of compound eyes and antenna.
e.They have blood filled body cavity named haemocoel.
Example: periplaneta Americana (Cockroach) Bombyx mori (Silkworm)
Carcinoscorpius (King crab -a living fossil).