Birdsnest Coral

Colonies of Seriatopora hystrix formed a tangled, bushy clump of fragile, slender, tapering branches with pointed tips. These clumps can grow to a metre (yard) across. In shallow positions with strong water movement the branches are thicker than they are in deeper or turbid habitats in sheltered positions. The corallites form neat rows of oval cup-shaped depressions with raised rims from which the polyps protrude at night. This coral can be cream, pink, yellow, brown or blue.

Seriatopora hystrix is native to the Indo-Pacific region. Its range extends from East Africa, Madagascar and the Red Sea through the Indian Ocean to tropical Australia, Japan, the South China Sea and the island groups in the West and Central Pacific. It occurs on reefs and reef flats, mostly at depths between 3 and 15 m (10 and 49 ft).

Seriatopora hystrix is a hermaphrodite, mature polyps producing both sperm and eggs. The sperm are liberated into the sea and get drawn into other polyps of the same or other colonies, and the developing larvae are brooded maternally. Self-fertilisation may be an important strategy for this species. When eventually released, the larvae settle within about 24 hours which suggests a limited dispersal range. Many settle within a few tens of metres of the parent colony, but others are probably swept along in warm currents and end up further afield. S. hystrix is a zooxanthellate species of coral, housing symbiotic dinoflagellates within its tissues. It has been found that these symbionts are transferred during the brooding of the larvae and that different species of Symbiodinium are associated with the coral in different parts of its range, a likely example of coevolution and specialization. Another means of reproduction is by asexual means; fragments of coral that become detached from branches can form new colonies if they are deposited in suitable locations. At times of stress, another form of asexual reproduction takes place that may allow some of the polyps to survive even though the parent colony dies. …