Mushroom Corals

Fungia corals can reproduce sexually or asexually (4). During sexual reproduction, eggs and sperm are released into the water where the egg is fertilised and develops into larvae (3). Within a fortnight, the larvae will settle on to hard substrate (4). Asexually reproduced young coral, or acanthocauli, can develop from partly buried, damaged or dying parent tissue. Either way, the result is vase-shaped polyp that gradually grows into a flattened disc, attached to the substrate via a stalk (3). The stalk of the 'mushroom' eventually dissolves, and the coral becomes mobile. The newly mobile coral rests on the bottom where it will mature and reproduce. The mobility of adult Fungia corals allows them to expand the reef by moving down-slope onto the soft substratum. This is an important process in reef ecosystems as it provides a hard substrate for other corals to establish and shelter for other invertebrates (3) (4). Fungia corals are abundant on unstable substrates and in volatile environments, uninhabited by many other coral species, and are able to withstand sedimentation, breakage and immersion by freshwater for short periods of time. To survive in such environments, Fungia corals are particularly successful in their ability to repair and regenerate their tissues and skeleton. When repair is impossible, asexual reproduction allows them to repopulate an area following a catastrophe (5). When Fungi are in immediate contact with other hard corals, they secrete a mucus that can damage coral tissues and prevents the over growth of these neighbouring corals. This mucus also plays a role in removing sediment from the coral, and facilitating in food capture (4). Fungia corals have been observed feeding on jellyfish, which may be their main food source, and is possibly the reason why these corals possess such large mouths. Occasionally, parasites reside inside the mouth; one particular parasite species, Fungiacava eilantensis, is found nowhere else in the world (3).

Fungia corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that trade in this species should be carefully regulated (1). Indonesia and Fiji have export quotas in place for this species (1). Fungia corals will form part of the marine community in many marine protected areas (MPAs), which offer coral reefs a degree of protection, and there are many calls from non-governmental organisations for larger MPAs to ensure the persistence of these unique and fascinating ecosystems (6).

Rather than forming colonies like most other corals, Fungia corals are usually solitary and generally free-living; that is, they are not attached to the substrate (except for juveniles). They are flat or dome-shaped, and either circular or elongate in outline (2). All species have wide slit-like mouths in the centre and short, tapered and widely spaced tentacles that are usually only extended at night. Very young Fungia (called acanthocauli) bear little resemblance to the adult form; they are shaped like flattened discs and are attached to the substrate via a stalk (3). Their resemblance to mushrooms gives these corals their common name.

The preferred substrates for Fungia corals are live coral and rubble, and they are more abundant on outer reef slopes than in lagoons (4). As they are free-living, and therefore readily moved by waves, Fungia are usually found below the depth of strong wave action. It is especially common on the slopes of fringing reefs where many species are usually found together (3).

Occurs in the Indian and Pacific Oceans, mostly restricted to tropical and subtropical latitudes, except for F. scutoria which is found in high latitude reefs (3).

Listed on Appendix II of CITES (1).

Fungia corals face the many threats that are impacting coral reefs globally. It is estimated that 20 percent of the world's coral reefs have already been effectively destroyed and show no immediate prospects of recovery, and 24 percent of the world's reefs are under imminent risk of collapse due to human pressures. These human impacts include poor land management practices that are releasing more sediment, nutrients and pollutants into the oceans and stressing the fragile reef ecosystem. Over fishing has 'knock-on' effects that results in the increase of macro-algae that can out-compete and smother corals, and fishing using destructive methods physically devastates the reef. A further potential threat is the increase of coral bleaching events, as a result of global climate change (6). Fungia corals may also potentially be threatened by coral harvesting. Fungia species are most popular in the dead coral trade, for use as ornaments or jewellery, rather than being traded live for aquariums. It is one of the four genera that are most frequently traded in the dead coral trade (7).

Fungia is a genus of corals in the family Fungiidae. It is monotypic with the single species Fungia fungites, which is found growing on reefs in the Indo-Pacific.