Hermit Crab Behavior

What to expect and what to watch our for

Crabs are not known for normal pet behavior. They are not cuddly, fuzzy, or cute (to most people). They have an incredible curiosity for their surroundings, and love climbing all over the place.  They also have a mobile home which must be changed from time to time.

Changing Shells-
(I'll have some pictured soon)

Some crabs only change shells out of absolute necessity. Others may change several times in a day. I've seen a crab change more than ten times in a day, and it ended up in the same shell that it started in!
Hermit crabs sometimes have a habit of doing mass-changes.  The largest crab will take a new shell, the next largest will take the largest's old shell, and so on all the way down to the smallest.  I have read of chains of over twenty crabs, and I have witnessed a chain of three, and it's fascinating to watch.  Check out some of the bio-related links to read more about shell chains.
Anyway, when a crab changes shells, it won't do it in a hurry unless a> it has no shell or b> it is being forced out of its shell.  Crabs that walk around without shells are either really sick or really weird (or molting), but they usually don't stay out of their shells for long. If you see one without a shell, make sure it stays in a humid area.

If a crab is being forced out of its shell, you will know it because the aggressor will be rocking the crab back and forth slowly.  The defending crab may lose limbs in the process and it usually makes an abrupt barking sound to show its discomfort. Eventually, the aggressor will move in or lose interest, and if the aggressor wins, the defending crab will take the aggressor's old shell.

If many replacement shells are present, crabs have no need to compete for shells and will go about their normal shell-changing procedure. When they first come upon a shell, they will do a quick inspection of the inside to see if it is occupied. They probe the outside for holes, turning it all the way around several times, and then conduct a more thorough inspection of the inside.  They may come almost all the way out of their current shell while they are inspecting the innermost regions of the prospective shell.  This whole process takes between a minute and an hour, depending on the crab.  if the crab is satisfied with the new shell, it will stand it up close to their current shell and, while holding onto their new shell with their legs, they will move their soft abdomen across into their new shell. Once moved in, they may inspect the new shell further.  many crabs practice a quick withdrawal into their new shell several times to make sure it is safe.  If they don't feel secure, they may insect their old shell and move back in.

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