Fire corals are hydrozoans, and thus have different type of polyps with different functions than anthozoan corals. The polyps of hydrozoans are near microscopic size and are mostly imbedded in the skeleton and connected by a network of minute canals. All that is visible on the smooth surface are pores of two sizes: gastropores and dactylopores. In fact, Millepora means 'many pores'. Dactylopores have long fine hairs that protrude from the skeleton. The hairs possess clusters of stinging cells (nematocysts) that inflict the stings on human skin. These hairs capture prey, which is then engulfed by gastrozooids, or feeding polyps, situated within the gastropores (2). As well as capturing prey, fire corals gain nutrients via their special symbiotic relationship with algae known as zooxanthellae. The zooxanthellae live inside the tissues of the coral, and provide the coral with food, which they produce through photosynthesis, and therefore require sunlight. In return, the coral provides the algae with protection and access to sunlight. Reproduction in fire corals is more complex than in other reef-building corals. The polyps reproduce asexually, producing jellyfish-like medusae, which are released into the water from special cup-like structures known as ampullae. The medusae contain the reproductive organs that release eggs and sperm into the water. Fertilised eggs develop into free-swimming larvae that will eventually settle on the substrate and form new colonies. Fire corals can also reproduce asexually by fragmentation (4) (5).
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