Such obvious question like ‘When does a hermit crab change its shell?’ is not difficult to answer. But there are more interesting things to know about hermit crabs that make you like nature. Or not. So, a hermit crab changes its shell when it has grown large enough to need to a bigger one.
Hermit crabs are unique for the fact that they have soft abdomen or tail which is folded up under the body. One thing that you should know is that the abdomen of the crab is not protected by its own shell. That is the reason why hermit crabs use empty snail shells as portable shelters and protectors.
But things don’t always go the way they want, there are fights between the hermits all the time. One hermit crab often has to fight with another one for possession of an attractive home. Things get scary sometimes especially when the homeseeker pulls out the original occupier and eats it before taking over the shell.
So how do the hermit crabs get in the shell?
One of the claws of hermit crab is larger than the other. The crab uses this claw to stop up the entrance after withdrawing into the shell. They also have the last two legs with roughened pads on its abdomen to grip the shell and hold the body in position. This video from BBC will show you the process precisely.
Partnership Under The Water
There is not always a fight in hermit crab kingdom, there is some friendship as well. Well, there is this kind of hermit crab that occupies sponge which grows at the same pace as the crab. The sponge is known as ‘sea-anemones’, and they are great partners with hermit crabs. The sponge takes up the residence on top of the shells. So, the crab provides the sea-anemone with transport, and the the sponge provides extra shield against attack to the crabs.
I told you, nature is awesome!!!