Mushroom corals of the family Fungiidae are flat or dome-shaped, with round or oval skeletons and a possible central arch. These corals are mostly solitarily and free-living (they are not attached to the substrate), and are commonly seen at all coral reefs on Koh Lanta dive trips.
Most mushroom corals are in fact a single, giant polyp, some with multiple mouths. A few species do actually form small 'colonies' in that several polyps live within the same, shared skeleton.
All species have wide, slit-like mouths with short tentacles that usually extend for feeding at night, except the Sunflower mushroom coral (Heliofungia actiniformis) which has very long tentacles extended during the day and is often mistaken for a sea anemone.
Free-living individuals can move, though very slowly. They do this by inflating and deflating its tissues. While smaller ones may be able to right themselves should they be accidentally overturned, bigger ones will die if this happens to them.
Young mushroom corals start life attached to a hard surface, and actually do look like a tiny stalked mushroom. In most species, as the corals mature, they eventually break away from their stalk and live life as adults, unattached to the bottom. In a few species, the adult coral remains attached, and the stalk is obscured by the growing disk.
3 species found on this page.
Elongate Mushroom Coral
(Ctenactis echinata)
Ctenactis echinata @ Koh Haa
The Elongate Mushroom Coral has an oblong-oval shape and is usually brownish, but may also be greenish.
This species is not colonial (it only has a single polyp/mouth) and is free living, with a dominant axial furrow.
The upper side has large, toothed costate septa (a septa is one of the radiating vertical plates within the corallite wall. When it extends beyond the coralite wall, it is called the costate). The underside has numerous pointed tips.
The Elongate Mushroom Coral can grow up to 25 cm long, and is common to all dive sites around Koh Lanta.
Common Mushroom Coral
(Fungia fungites)
Fungia fungites @ Koh Haa
The Common Mushroom Coral has a circular coral plate, occasionally with an arched center. The septal teeth are triangular and pointed.
The tentacles are short and bubble-shaped. The colour may vary from greyish-green to yellowish-brown to pink.
The Common Mushroom Coral is often seen solitary, or in small groups, usually in shallower areas. This single coral polyp can grow to 28 cm, but is usually observed 5 cm to 15 cm.
Tongue Mushroom Coral
(Herpolitha limax)
Herpolitha limax @ Koh Haa
The Tongue Mushroom Coral, also known as the Slipper Coral or Boomerang Coral, is a colonial, free-living mushroom coral, with many polyps living within a single colony.
Colonies may be flat or domed, and are usually elongate, with rounded ends. Colonies may also be Y, T or X shaped.
Tongue Mushroom Coral axial furrow with slit-like mouths
The Tongue Mushroom Coral has an indistinct axial furrow which runs most of the length of the colony, and contains multiple irregularly spaced slit-like mouths.
There are many smaller secondary mouths occurring outside the axial furrow. Septa costae are arranged in rows perpendicular to the colony edge and have regular, densely packed teeth which are interrupted by the numerous secondary mouths.
Tongue Mushroom Coral many secondary mouths
The white-tipped 'tentacles' along the costate septa rows are short and partially transparent. These are not true tentacles but inflated portions of the costate septa tissues. The true colony feeding tentacles are extended at night.
The Tongue Mushroom Coral grows to 50 cm, but more commonly observed around 20 - 30 cm at the dive sites around Koh Lanta.
This species may be pale or dark brown, or greenish-brown and is found on reef slopes.
