Electric blue hermit crab
Calcinus elegans
Also known as Electric Blue Leg Hermit Crab, Blue-Banded Hermit Crab, Elegant Hermit Crab, Blue knuckle hermit crab
SaltwaterCrab
Care at a glance
- Temperature
- 72–79°F
- 22–26°C
- pH
- 8.1–8.4
- Adult size
- 2 in
- 5 cm
- Minimum tank
- 20 gal
- 75 L
- Temperament
- Peaceful
- Social behavior
- Solitary
- Swim level
- Bottom
- Difficulty
- Easy
- Breeding
- No record
- Rarity
- Common
- Reef safe
- Reef safe
- Family
- Diogenidae
- Origin
- Indo-Pacific, from East Africa to Hawaii and French Polynesia, north to southern Japan and south to northern Australia
Overview
The electric blue hermit crab is an active scavenger and a useful part of a reef cleanup crew. It is easy to keep.
Did you know
The electric blue hermit crab's enlarged left claw works as both a weapon and a trapdoor. It folds flush across the shell opening to seal the crab safely inside whenever a predator gets too close.
Caring for the electric blue hermit crab
Give the electric blue hermit crab at least 20 gal (75 L), with live rock that grows algae for it to pick at. Leave enough open rock and sand for it to move around freely. Keep a good supply of empty shells in a range of sizes.
Keep the water at 72 to 79°F (22 to 26°C) with a pH of 8.1 to 8.4. It grazes green hair algae and cyanobacteria, and it cleans up detritus and leftover food.
It is generally peaceful toward fish and corals, so it counts as reef safe. It is not snail safe. If it outgrows its shell and no spares are available, it will attack and kill a snail to take its shell. Expect some squabbling over shells if several share a small tank.
Good to know
Calcinus elegans is a hermit crab in the family Diogenidae. It is unmistakable for its electric blue legs banded in black and yellow, blue eyestalks and green claws tipped in white. Like other Calcinus, it is a left-handed hermit. It grows into shells up to 7.5 cm long.
In the wild
The electric blue hermit crab ranges across the Indo-Pacific, from East Africa to Hawaii and French Polynesia. It reaches north to southern Japan and south to northern Australia. It lives intertidally and on shallow coral reef and rubble, down to about 5 meters. There it grazes rock and rubble for algae and organic debris, carrying its shell home wherever it forages.
Common questions
What size tank does an electric blue hermit crab need?
An electric blue hermit crab needs at least 20 gal (75 L). It spends most of its time in the bottom.
What temperature and pH does an electric blue hermit crab need?
An electric blue hermit crab is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.
What does an electric blue hermit crab eat?
An electric blue hermit crab grazes green hair algae and cyanobacteria, and it picks at algae on live rock. It also cleans up detritus and leftover food.
How big does an electric blue hermit crab get?
An adult electric blue hermit crab reaches about 2 in (5 cm).
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