The Crab
The crab is an animal known as a crustacean which is also like the grasshopper and the spider, an arthropod. Crabs have sensory hairs on their legs and antennae which allow them to feel their surroundings and to smell their food. A pair of optic nerves run directly to the two lateral eyes. There are eight pairs of haemal nerves that extend into the body of the crab. These contain motor and sensory fibers and are distributed mainly to the tissue and the membrane. The sixth pair of haemal nerves sends branches to the heart and intestine. These are purely sensory nerves and they run through the legs and gills as well.