Hermit crabs are the only crabs that do not have shells but use a discarded one protect themselves. It selects and discards shells as its body grows. It does not appear that the hermit crab “lost” its shell by some evolutionary change and is attempting to get it back. Rather, it seems more logical that it was uniquely designed by the Creator to live exactly this way. A hermit crab’s body is asymmetrically twisted to fit inside the shells it inhabits. Its right claw is much larger than the left one and acts as a protective door when it withdraws into the shell to hide or sleep. Hermit crabs have a symbiotic relationship with sea anemones. Anemones protect themselves with stinging cells, but hermit crabs are allowed to actually pick them up and attach them to their shells. Both benefit from this cooperation. It’s hard to imagine a hermit crab losing its shell, regretting that development, trying to get it back, and twisting its body out of shape to fit into another animal’s shell. And how many tries did it take before the first anemone granted permission for the first hermit crab to pick it up? Trial and error could not have accomplished all this. The hermit crab lives exactly as it was designed to live by the Creator of the universe.
Chapman, Geoff. “Wonders of Creation: Those Clever Little Hermit Crabs.” Creation 16(1):51 December 1993