This is probably the largest group of animals. These animals are bilaterally symmetrical and segmented. There is an open circulatory
system, and so the blood does not flow in well defined blood vessels. The coelomic cavity is blood-filled. They have jointed legs (the word
‘arthropod’ means ‘jointed legs’).
Some familiar examples are prawns, butterflies, houseflies, spiders, scorpions and crabs.
