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Step 1
Observe the hermit crabs three sections: a head, the body and an abdomen. The abdomen is protected by the shell and houses the reproductive organs and digestive system.
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Step 2
Notice the two pairs of antennae on the hermit crab. The long pair is used to feel and touch and is more commonly called "feelers." The shorter pair is used to help the crab smell and taste.
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Step 3
Look for the eyes, which are made up of faceted lenses that help pick up fine movements. Under the eyes are the mouth parts called maxillipeds. Food is moved into the mouth by three pairs of appendages. These appendages can also be used for grooming.
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Step 4
Examine the claws, otherwise known as chelipeds. The left claw is the larger claw and is mainly used as a defense mechanism to seal off the opening to the shell. The right claw is the shorter claw and is used for eating and scooping water into the maxillipeds.
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Step 5
Inspect the pereiopods, which are the legs. Including the chelipeds, the land hermit crab has 10 legs. Walking and movement is done with the second and third pairs of legs. The fourth pair of legs are stubby and used for moving in and out of the shell. The fifth pair of legs end in pinchers and are used for removing excrement from the shell and cleaning the gills, which are located between the fourth and fifth pereiopods and are used for breathing.
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Step 6
Discern between male and female parts of the crab. Female crabs have gonopores near the base of the third pair of legs. The gonopore in the female crab is the opening of the oviduct. Female crabs also have pleopods on the abdomen which are used for carrying eggs. Male crabs have hair concealing openings at the bottom of the fifth pair of legs.
