Anemone hermit crab

Care at a glance

Overview

An aggressive, active scavenger for a rough fish only or large predator tank, not a reef. It eats snails, small hermit crabs, tube worms, and any fish it can catch asleep on the sand, it knocks over frags and loose rock, and its anemones sting whatever they touch, so it gets a reef safe with caution verdict at best, though medium to large fish that stay off the bottom are fine company. Keep one per tank, since two will steal each other's anemones and fight over shells. Feed it meaty foods such as raw shrimp, clam, mussel, squid, and silversides two or three times a week, and remember the anemones need their own feeding of meaty bits to stay on the shell. Water at 22 to 27 C and pH 8.1 to 8.4 suits it.

In the wild

The anemone hermit crab lives on coral reefs, reef flats, and sandy lagoons across the Indo-Pacific, from East Africa and the Seychelles to Japan and Hawaii, from the intertidal down to about 95 m. It is a big, heavy hermit that drags a large snail shell, usually with one or more Calliactis anemones stuck to it. Give it a tank of 150 liters or more with a sand bed, stable rockwork it cannot topple, dim light, and a supply of large empty shells such as whelk and turban shells. Keep the water at 22 to 27 C, pH 8.1 to 8.4, and specific gravity 1.023 to 1.025.

Good to know

Dardanus pedunculatus is a left handed hermit crab in the family Diogenidae, described by Herbst in 1804 as Cancer pedunculatus. The body reaches about 10 cm, with a mottled tan and cream carapace, white eyestalks banded in red, and a left claw much larger than the right that it uses to seal the shell opening. Its trademark is the anemones it collects at night. It strokes and taps a Calliactis polypus until the anemone lets go of the rock, then sets it on its own shell, and when it moves to a bigger shell it moves the anemones too. The stinging tentacles put off octopus, its main predator, and the anemones get a ride and scraps from the crab's messy meals.

Common questions

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