which means that a single polyp produces both male and
female gametes within one breeding season. Two different
modes of reproduction are known (see Fig. 3): (i) internal
fertilization and release of settlement-competent planula
larvae (also known as brooding) or (ii) external fertilization
with a 1–4 days planktonic embryogenic stage depending
on the species and water conditions (also known as broadcast spawning). Reproductive cycles are often dependent on
external cues, such as seasonal temperature (spawning usually occurs when the water temperature reaches its annual
maximum of 28–30°C) and the lunar cycle. Brooders may
release larvae daily, without a visible pattern, or have
monthly or seasonal reproductive cycles, whereas broadcast
spawners usually show an annual cycle where they spawn in
a few consecutive nights of two consecutive months. In a
recent review, Bairdet al.(2009) found out that of approximately 400 scleractinian species investigated, 16% are
brooders and 30% are gonochoric. Self-fertilization has
been observed in hermaphroditic species (both in broadcast
spawners and in brooders), and in some brooding species
(i.e. Pocillopora damicornis) larvae can even be produced
asexually. For detailed information on the biology of sexual
coral reproduction, see Baird et al. (2009) and Harrison
and Wallace (1990).