Electric Blue Hermit Crab (Calcinus elegans)

The legs on this hermit are genuinely electric blue, not just blue-tinted, with a bright orange band right at the tips that makes it one of the most photographed hermits in the trade despite spending most of its life dragging around a borrowed shell. Like every hermit it's constantly on the lookout for a bigger home, and a shortage of spares can trigger a scramble where several crabs line up in size order and swap shells down the chain — ecologists actually call this a vacancy chain.

Care level: Easy · Temperament: Peaceful · Max size: ~1.5" · Min tank: 10 gal · Reef safe: Yes · Diet: Omnivore, algae + scavenger