Jack Gansky, age 11, of Warminster, Pennsylvania, for his question:
What are hermit crabs?
A human hermit lives alone, isolated from the rest of humanity, usually in the wilds. Chances are he would find it hard to offer a sound reason for his choice of life style. The hermit crab lives a solitary life in the salty sea for a very sensible reason. He is hiding from his hungry enemies which are many.
The sea's assortment of crusty coated crabs scuttle around sideways on crusty coated legs or so it seems. Actually, a number of large and small crabs do not have the usually crusty armament, at least not all over their bodies. The heads, .pincers and the first two pairs of walking legs are sheathed in shell. But the banana shaped abdomen is unprotected.
These are the hermit crabs. You might mistake them for winkles or whelks because they tuck their unprotected tummies into the discarded shells of various sea creatures. The head, claws and a few walking legs poke, out through the open end of the shell. But during rest periods, a hermit crab tucks his entire body into his borrowed shell and places his extra large right claw across the doorway.
The third and fourth pairs of soft crab legs are used to hold onto the inside walls of the shell. The fifth pair is curved to hold around the shell's central column. The infant hermit crab is a shrimp like larva. After four molts and a period of hazardous swimming, he is ready to settle down and occupy his first apartment. Being a small fellow, he chooses a winkle or some other small shell.
As he grows, a hermit crab needs to occupy a larger and then a larger house. Changing his address is quite a problem and he gives the matter his full attention. If possible, he investigates several discarded shells, exploring the insides with his claws. When satisfied, he turns around and tucks his unprotected tummy~inside.
Some of the smaller hermit crabs live near tropical islands and make their homes in bits of bamboo. Sometimes a larger one lives in a hollow coconut shell. Others shelter themselves in coral crevices and once in a while a large deep water hermit crab makes himself at home in an old ship's lantern. A few types gather sea anemones and fasten them on their roofs and one cloaks his shell in sea mosses.
Several larger hermit crabs live on beaches and spend most of their time out of water. One of these is the robber or coconut crab of the South Pacific islands. He is a shell less hermit, six inches wide and weighing several pounds. This fellow does not bother to shelter himself in a borrowed shell.
The female hermit crab produces perhaps 15,000 little purple eggs. While the eggs are attached to her body, now and then she comes partly out from her shell and fans streams of water around them. As the tiny larvae hatch, she moves aside and uses the bristles on her fourth pair of legs to brush them out into the sea. In a year, the few that survive will be ready to produce eggs of their own.