Colonies are submassive, encrusting, laminar or subarborescent. Much of this variation may occur in the same colony but some colonies are composed only of plates. Hydnophores are 5-8 millimetres diameter. Tentacles are often extended day and night; they are long and shaggy and of uniform length.
Cream or dull green.
All reef environments, but especially lagoons and protected slopes.
Taxonomic note: This species is divisible into several smaller semi-distinct taxonomic units. The shape and degree of branch development, in particular, shows great regional variation. These regional variants do not overlap geographically. Source reference: Veron (2000). Taxonomic references: Wijsman-Best (1972), Chevalier (1975), Veron, Pichon and Wijsman-Best (1977). Additional identification guides: Randall and Myers (1983), Veron (1986), Sheppard and Sheppard (1991), Nishihira and Veron (1995), Carpenter et al. (1997).
displaying probable distribution of species. Points indicate recorded sightings from OBIS.
Hydnophora exesa.Tanzania.Colonies commonly have encrusting bases and an upper surface of irregular branches.Charlie Veron.
Hydnophora exesa.Great Barrier Reef, Australia.This species usually has a rough appearance due to projecting monticules.Ed Lovell.
Hydnophora exesa.Great Barrier Reef, Australia.Stunted interlocking branches in a colony exposed to wave action.Charlie Veron.
Hydnophora exesa.Papua New Guinea.Colonies may be entirely encrusting.Jim Maragos.
Hydnophora exesa.Vietnam.Branch ends with tentacles fully extended.Charlie Veron.
Hydnophora exesa.Houtman Abrolhos Islands, south-western Australia.Surface of an encrusting plate.Charlie Veron.
Hydnophora exesa.Lord Howe Island, south-eastern Australia.Detail of valleys with tentacles partly extended.Neville Coleman.