Something must have gone wrong for the hermit crab.
Snails and turtles get their own shells to protect their soft bodies. Hedgehogs can roll up into prickly bundles. Squid can defend themselves with a blast of black ink. Cats can scratch and dogs can bite. Birds can fly away.
But the hermit crab, it seems to me, has not evolved correctly. He has a soft, vulnerable abdomen that is totally exposed to the big, bad world and all the predators therein. The hermit crab has no shell in which to hide, no barrier of protection against the things that want to destroy him, and – more than that – no home.
So the hermit crab, realising his vulnerability, sets off to explore the world around him, sans shell. And that world is beautiful, you know. There’s so much to see, so much to experience. It’s stunningly, breathtakingly beautiful – but dangerous. The hermit crab knows instinctively that he can’t just crawl around indefinitely like this, hiding under this rock tonight and that plant tomorrow. His luck won’t hold out. Something will get him. Something will hurt him.
The first time he sees an empty shell, it’s like a little light bulb lights up above his head. A home! Security! Protection! He checks it out, tentatively at first, and decides that this is the place for him. It’s a bit big, and has that uneasy atmosphere of unfamiliarity, but it’s an improvement, right? You can’t just go wandering around without a shell. You’ll get hurt. You need a home! Now he looks just like all the other crabs. He’s not the weird naked one any more.
And actually, once he’s properly moved in and settled for a while in the second hand shell, he realises that it’s become a perfect fit. Sure, when he first got there, it was so big that he could retreat right back inside it and curl his whole body up so that he was completely hidden, and nowadays it seems that he can’t quite manage that, but it’s only his claws that are left poking out, and they’re tough enough to withstand whatever might come along, aren’t they?
But then some more time goes by, and suddenly the hermit crab discovers that he’s been sleeping with half his body outside his shell, and it’s getting really cramped and uncomfortable in there, and last night there was a close call when that big scary thing with teeth nearly took his leg off.
There’s no denying it any longer. As much as he loved that shell, he’s outgrown it. It’s time to move.
So the hermit crab moves out and moves on and moves into a new shell. This one’s bigger, and has a fancy looking sea anemone on the top. Although the hermit crab feels a bit disoriented at first, and perhaps even uncomfortable (having actually started to grow into the shape of the old shell), he soon adjusts and finds that the move was the best thing he could have done for himself. Once again he settles in and finds that he has space to grow and a safe place to hide. He’s glad he was forced out of the old shell.
But much to the hermit crab’s dismay, he finds that he keeps growing and changing. Time and time again, he gets that niggling feeling of discomfort, of having stayed too long in a shell that no longer fits him. When that happens, he becomes vulnerable once again. He gets hurt more easily; he’s at greater risk than the other hermit crabs, the ones who have shells that fit properly. He is no longer prepared for or protected against what may come along to harm him. Not only that, but he doesn’t have enough space to grow. He’s stuck. He’s suffocating. Staying put is simply not an option.
And so that is the life of the hermit crab. He moves from one temporary home to the next, each one unfamiliar and intimidating at first, but soon proving to have been a good move. He has room to grow and change and adapt, until he finds that he has actually grown and changed a bit too much for this particular shell that was once so full of potential but now leaves him stunted and stifled and at an increasingly greater risk of getting hurt. Leaving is a risk, especially as he might have to fight other hermit crabs for the next shell, meaning he could be left without any shell at all – or worse, injured or killed in the battle.
Yet, whatever the risk, the hermit crab must leave when that shell becomes too small for him. No matter how familiar and safe it feels, no matter how attached he’s become to it, no matter how frightening everything looks out there, outside of his shell. He has no choice. For a while, he can ignore the warning signs. Then he can endure the discomfort. But there comes a point where finding a new shell is the only remaining option. The transition will most likely be a smooth one; the hermit crab will find a new shell; life will go on as normal until the time comes for the next shell shift.
Another hermit crab will move into the abandoned shell. There’s no going back to the old shell.
Maybe that’s the scariest part.