CRUSTACEANS

Named for their hard but flexible exoskeletons, Crustaceans are part of the phylum Arthropoda. Characteristics include appendages having multiple joints and having a carapace, or shield, over their head. Their bodies consist of repeated segments; head , thorax, and abdomen, some which fuse together in adulthood. Since the shell is a barrier to sensory nerve endings, crustaceans have developed antennae, various sensory hairs, bristles, pores, and slits to function as chemoreceptors (sense of smell) and to detect vibrations. Blood-filled gills, sometimes located beneath the exoskeleton, were developed to respirate through their hard shell. Their compound eyes can see 270 degrees around. Crustaceans grow by splitting the exoskeleton and the animal wriggling out - molting.

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