Skip to Content
Sign up
Report an error

Heterocyathus aequicostatus

Milne Edwards and Haime, 1848

Sometimes zooxanthellate. Corals are solitary, free-living, and have a flat base. They have a commensal relationship with a sipunculid worm (Aspidosiphon corallicola) which moves the coral about on soft substrates and prevents it from becoming buried. Tentacles are usually extended only at night. Larvae initially settle on a microgastropod shell which they usually envelop during subsequent growth. Corals have only one corallite which is circular. They have prominent costae.

Colour: Pale brown, often with a greenish oral disc.

Habitat: Always found on soft horizontal substrates at depths of 20 metres or more, usually in association with Heteropsammia cochlea and the fungiid Cycloseris cyclolites.

Abundance: May be locally abundant (commonly 40 individuals per square metre).

Similar species:

Taxonomic note: Source reference: Veron (2000). Taxonomic reference: Hoeksema and Borel-Best (1991). Additional identification guides: Veron (1986), Sheppard and Sheppard (1991), Carpenter et al. (1997).

Map displaying probable distribution of species. Points indicate recorded sightings from OBIS.
Heterocyathus aequicostatus.  Philippines.  A small cluster.  Doug Fenner.

Heterocyathus aequicostatus.Philippines.A small cluster.Doug Fenner.

Heterocyathus aequicostatus.  null.  These corals, the size of a small coin, only occur on soft inter-reef substrates.  Clay Bryce.

Heterocyathus aequicostatus.null.These corals, the size of a small coin, only occur on soft inter-reef substrates.Clay Bryce.

Heterocyathus aequicostatus.  Philippines.  With tentacled retracted. The strongly developed costae are readily seen.  Pat Colin.

Heterocyathus aequicostatus.Philippines.With tentacled retracted. The strongly developed costae are readily seen.Pat Colin.

Heterocyathus aequicostatus.  Great Barrier Reef, Australia.  With tentacles partly extended.  Dave Fisk.

Heterocyathus aequicostatus.Great Barrier Reef, Australia.With tentacles partly extended.Dave Fisk.

Heterocyathus aequicostatus.  Ryukyu Islands, Japan.  Showing calice structures.

Heterocyathus aequicostatus.Ryukyu Islands, Japan.Showing calice structures.

Heterocyathus aequicostatus.  Ryukyu Islands, Japan.  Showing lower surface.

Heterocyathus aequicostatus.Ryukyu Islands, Japan.Showing lower surface.

Heterocyathus aequicostatus.  Ryukyu Islands, Japan.  Showing septo-costae.

Heterocyathus aequicostatus.Ryukyu Islands, Japan.Showing septo-costae.

Heterocyathus aequicostatus.  Ryukyu Islands, Japan.  Showing worm hole.

Heterocyathus aequicostatus.Ryukyu Islands, Japan.Showing worm hole.