Halloween Hermit Crab care guide
Halloween Hermit Crab (Calcinus elegans) — minimum tank 40 L, temperature 24-26 °C, pH 8.1-8.4.
Compiled by Aquairi from published sources · Published · Updated
Overview
Halloween Hermit Crab (Calcinus elegans) is a marine hermit crab of the family Diogenidae, listed in the Aquairi knowledge base as a beginner-level species. Striking hermit with black-and-orange striped legs. Eats detritus and algae. Reef-safe in groups; provide larger empty shells to prevent attacks on snails.
Taxonomy
- Family: Diogenidae
- Genus: Calcinus
- Scientific name: Calcinus elegans
- Common synonyms: Halloween Hermit, Striped Hermit
Habitat
Hermit crabs of the family Diogenidae are anomuran crustaceans that protect their soft, asymmetric abdomen inside an empty gastropod shell, moving to larger shells as they grow. Reef species graze algae, biofilm and detritus across the rockwork and substrate. In the Aquairi knowledge base this species is recorded from Indo-Pacific.
Tank requirements
- Minimum tank volume: 40 L (10.6 US gal)
- Adult size: 2-4 cm
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- GH: 8-12 °dGH
- KH: 8-12 °dKH
- Salinity (specific gravity): 1.024-1.026
- Lifespan: 2-5 years
Diet
The species is an omnivore, grazing algae, biofilm and detritus across the rockwork and substrate; in aquaria its diet is supplemented with dried algae and sinking foods when natural growth is scarce.
Compatibility
The Aquairi knowledge base lists this species as peaceful. Suitable tank mates include Reef fish, Other hermits. It should be kept away from Snails (provide spare shells!).
Breeding
Breeding requires an extended planktonic larval stage in open water before the young settle, which makes captive reproduction very difficult and rarely accomplished in home aquaria. Most specimens in the hobby are wild-collected.
Breeding the Halloween Hermit Crab (Calcinus elegans)
Overview
Calcinus elegans (H. Milne-Edwards, 1836) is a hermit crab of the Indo-West Pacific, ranging from eastern Africa to islands south of Hawaii in shallow tidal and subtidal zones at 0-20 m. It is a nocturnal omnivorous detritivore that scavenges detritus and decaying plant and animal matter. Like all hermit crabs it occupies empty gastropod shells, preferring dog whelk shells and swapping shells as it grows.
Sexing
Hermit crab sex is determined by gonopores on the leg bases, which is difficult to check inside an occupied shell. During courtship males of Calcinus elegans rotate the female's shell and rub their claws around the shell opening; notably, this species does not perform a shell exchange during mating.
Spawning & Larvae
After mating the female carries fertilized eggs attached to her abdomen inside the shell until they hatch. The larvae emerge as planktonic zoeae that drift and feed in the water column, passing through several zoeal stages and a glaucothoe (post-larval) stage before finding a first shell and settling as juveniles.
Common Challenges
- Planktonic zoeae are drawn into skimmers, filters and pumps in a closed system.
- Larvae require live planktonic food and stable rearing conditions not available in a display.
- Newly settled juveniles need a supply of tiny empty shells, which a tank rarely provides.
- The multi-stage larval cycle through zoeae and a glaucothoe is impractical to support at home.