Usually the entire body of Crabs is covered with a hard, calcified armour. The Hermit Crab however lacks this protection on the hindmost part of its body, the abdomen, which is soft and vulnerable. It protects its abdomen, which contains such important organs as the liver and the gonads, by inserting it into a gastropod shell. For this purpose the abdomen is bent, so that it fits in the curvature of the snail-house. The outer bend of the abdomen bears some little appendages which enable the crab to hold on to the inside of the shell. The reduced 4th and 5th pairs of legs serve the same purpose. When walking the animal drags its house along. In water the weight of the shell is diminished, and so the Hermit Crab, in spite of its burden, can zealously run about. In case of danger the Hermit Crab withdraws into the shell as deep as possible. In the shell there is no room for two big pincers. Therefore the Hermit Crab has but one. When hiding in the shell it uses this pincer to guard the entrance. When the crab grows and does not fit in its shell any longer, it looks for a bigger one. The original occupant, if still present, is picked out. Then, quickly and nervously, the crab moves over into its new home.


From Redondo on 12/15/05