Euphyllia is a genus of stony corals that comprises a number of different species and sub-species, all of them characterized by having large polyps.
Euphyllia comprises several species, the ones below being the most important:
- Paraancora – also known as the branching hammer coral, this species is wide-spread in the Indo-Pacific area. These types derive their characteristic appearance from the large tentacles with a knob at the end, but they present large variations in terms of coloring – they come in all shades of brown, but fluorescent colors are not uncommon either;
- Divisa – found mainly in the reefs around Australia, Fiji, in the East China Sea and in Sotheast Asiaas well as around Palau, these corals feature long tentacles that extend into smaller branches with a rounded, knob-like tip. The tentacles are usually green, with light-colored endings;
- Paradivisa – common around American Samoa and the Indo-Pacific, too, these corals are often referred to as frogspawn coral. These corals have very long tentacles that end in not one, but multiple branches, usually of the same color as the tentacle itself;
- Glabrescens – also known as torch coral, this species is common in the Gulf of Aden, in the Iranian Gulf, in the Southwest of the Pacific, around Australia and in the East China Sea. Not nearly as spectacular as the other Euphyllia species, torch corals are usually brown or green, with a cream-colored knob at the end of the tentacle;
- Paraglabrescens – a very rare and special species, found in the East China Sea, Papua New Guinea as well as around the Phillippines. They resemble E. glabrescens in every way, with only two minor differences: the tentacles are green or grey and they are shorter;
- Cristata – found in the Andaman Sea, in certain reefs around East Africa and Southern Asia as well as in the West Pacific, they have shorter tentacles. In terms of coloring, they range from almost clear to green and grey, with tips colored differently;
All species belonging to the genus proliferate quickly and they can form large colonies over very short periods of time. When left in their natural habitat, they reproduce by releasing eggs and sperm, but they might choose to proliferate asexually, by means of budding, that is, the production of small, new polyps that grow from the base of the colony. They prefer low to moderate water flow, strong enough to keep the tentacles in movement and they thrive well in clear waters as well as in dimmer, more turbid ones.
These species are about the only types of corals that have stinging cells, which they use for protecting themselves. Luckily, the stinging tentacles differ from the others by their length, so they can be avoided easily. In strong currents, Euphyllia tend to develop sweeper tentacles that will become eventually separated by the flow and will travel to a location where they can start a new colony.