What is the proportion of arthropods among the total known animal species?

Which feature is common among the fly,mosquito,and cockroach?

Haemocoel is present in

In many arthropods,the head and thorax are fused to form a cephalothorax. However,in which of the following classes of animals is the body divided into head,thorax,and abdomen?

Maximum diversity is found in which of the following phylum?

In the given figure,what do $A$ and $B$ represent respectively?