Hermit crab in an old helmet shell

Sea life: Hermit crabs

Hermit crab in an old helmet shell
Hermit crab in an old helmet shell

I’ve been holding off on this post chiefly because hermit crabs are devilishly difficult to photograph. They look really cool, beetling around on the sand, but getting the camera to an angle that captures their little hairy legs and beady eyes is tricky. Plus, at the first hint of interference, they disappear into their shells.

Large hermit crab at Long Beach
Large hermit crab at Long Beach

Most of our local dive sites are overrun with hermit crabs. I mean it – I spend a fair amount of time lying on the sand waiting for Tony to finish skills with his students, and these little guys are ubiquitous.

Hermit crab on shell patch
Hermit crab on shell patch

There are patches of shells at Long Beach that look kind of deserted, but if you watch for a while you can see ten or twenty hermit crabs crawling over each other. I wonder whether this isn’t the equivalent of a used car lot for them: hermit crabs use empty shells from other molluscs as their homes. When they outgrow the shell, they must find a new one, and quick as a flash crawl out of the old shell and into the new. There is a high degree of competition for good shells. More than once we’ve seen two of these little guys tussling over real estate.

When out of their shells, these little crabs apparently look more like lobsters, with a soft tail part (hence the need for a shell). We get a couple of different kinds in the Cape, but most of them have pink hairy legs and bad attitude. They are hugely entertaining if you just lie and watch them, but as soon as you pick them up they retreat into their shells (justifiably so) and wait to be released.

Overbalancing - shell too large?
Overbalancing - shell too large?

As the crabs grow, they must find larger and larger shells as homes. The competition is fierce. Sometimes we see absolutely huge, venerable granddaddies like the one below, with a forest of sea lettuce on his shell.

Hermit crab with decorations
Hermit crab with decorations

We see them on day as well as night dives, and they seem to be quite active at night. Here’s one I found in the shallows one evneing at Long Beach.

Hermit crab at night
Hermit crab at night

They can be quite fierce – every evening the starfish are removed from the Touch Pool at the Two Oceans Aquarium because otherwise, while unsupervised, the hermit crabs nip on their limbs.

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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