Stony Corals

It is thought that the differences in the shape of tentacles between Euphyllia species may be related to specialised feeding habits (2). These tentacles, unlike many other corals, do not possess clusters of stinging cells, and so may be adapted to capture food particles using water and cilia (microscopic hair-like projections), (2). Euphyllia corals also possess specialised tentacles that extend further than the normal feeding tentacles. These 'sweeper tentacles', can extend up to eight inches further than the normal tentacles and have numerous powerful stinging cells (nematocysts), that can cause significant localised damage to other corals that are growing nearby (4). On reefs where there is fierce competition for space, this is an extremely good defensive adaptation to possess. Euphyllia corals have separate male and female colonies (not all corals do), and most release eggs and sperm for external fertilization in the water, which then form larvae. In equatorial localities however, some may brood larvae internally (2). In captivity, asexual reproduction is much more common (4).

Euphyllia 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 has a quota system for corals, monitored though CITES. The aim of the quotas are to ensure harvest are kept at a sustainable level, but in reality, they are hard to set at the right level due to a lack of knowledge regarding coral biology. In 1999 the European Union CITES Scientific Review Group considered that some of the Indonesian quotas were too high and placed a ban on the import of E. divisa and E. glabrescens, and then in 2000 extended this trade suspension to all Euphyllia species (7) (8). Euphyllia 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 (5).

Whilst most coral species are identified entirely by their skeletons, for Euphyllia species it is necessary to look at the living coral polyp to distinguish between different species (2). The coral polyp is basically an anemone-like animal that secretes a skeleton, and possesses tentacles, and polyps form colonies which join together at the base of their skeletons. Each of the 15 species of Euphyllia that are currently known has very differently shaped large and fleshy tentacles, which are extended during the day and night (2). Euphyllia corals may be green, brown, pink, copper and occasionally blue, and the tips of the tentacles may be a different colour to the rest of the polyp (3). The most well known Euphyllia coral is E. ancora, commonly called hammer or anchor coral. This blue-grey to orange coral, with pale cream or green borders to the tentacles, may form continuous cover over the substrate, for many meters across (3). E. divisa has cream or green tentacles with pale, globular tips, the appearance of which gave rise to its common name 'frogspawn coral' (4).

Euphyllia corals occur in a wide range of reef environments; particularly shallow reefs (3).

Occurs in the Indian and Pacific Oceans, from Mozambique, up to the Red Sea, to southern Japan, northern Australia and the Fiji Islands (3).

Listed on Appendix II of CITES (1).

Euphyllia 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 (5). A more specific potential threat to Euphyllia corals is harvesting. Its colourful fleshy tentacles make it a desirable species for aquariums, and is therefore one of the species that dominates the live coral trade (6).

Euphyllia is a genus of large-polyped stony coral. Several species are commonly found in marine aquariums. The genus includes the following species:

Euphyllia baliensis Turak, Devantier & Erdman, 2012 – bubble coral Euphyllia cristata Chevalier, 1971 – grape coral Euphyllia glabrescens (Chamisso & Eysenhardt, 1821) – torch coral Euphyllia paraglabrescens Veron, 1990

The following species have been taxonomically reclassified into the Fimbriaphyllia genus under the Caryophylliidae family

Euphyllia ancora (Reclassified as Fimbriaphyllia ancora)Veron & Pichon, 1980 – hammer coral Euphyllia divisa (Reclassified as Fimbriaphyllia divisa)Veron & Pichon, 1980 – frogspawn coral Euphyllia paraancora (Reclassified as Fimbriaphyllia paraancora)Veron, 1990 – branching hammer coral Euphyllia paradivisa (Reclassified as Fimbriaphyllia paradivisa)Veron, 1990 – branching frogspawn coral Euphyllia yaeyamaensis (Reclassified as Fimbriaphyllia yaeyamaensis)(Shirai, 1980) - Thick branched frogspawn coral