Mushroom corals can reproduce sexually or asexually (5). During sexual reproduction, eggs and sperm are released into the water, where the egg is fertilised and develops into a larva (3). Within a fortnight, the larva will settle on to a hard substrate (5). Asexually reproduced young coral can develop from partly buried, damaged or dying parent tissue. Either way, the result is a vase-shaped polyp that gradually grows into a flattened disc, attached to the substrate via a stalk (4). 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 (4) (5).
The mobility of adult mushroom corals allows them to expand the reef by moving down-slope onto the soft substrate. This is an important process in reef ecosystems as it provides a hard substrate for other corals to establish, as well as shelter for other invertebrates (4) (5).
When mushroom corals 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 facilitates food capture (4). However, mushroom corals receive the majority of their nutrition from symbiotic algae, known as ‘zooxanthellae', which live within their tissues. The algae provide the corals with nutrients through photosynthesis, and in return receive a stable environment in which to live (3).