Some species of insects are parthenogenic. The female organism ,under certain circumstances ,can produce fertile offspring without mating. A complex developmental process is common in insects. This process is called metamorphosis . They contain a ventral nerve cord and a brain.
Excretory organs vary from green glands to Malpighian tubules.
They are coelomates . The phylum contain the most known species than all the other phyla combined. Lobsters, crayfish, crabs, and shrimp. These organisms contain two body parts the cephalothorax and abdomen. Two compound eyes and two pairs of antennae.