Star polyp

Morphology

Briareum violaceum forms thin encrusting sheets over rocks or live substrate. The colonies consist of two layers, the basal layer (medulla), which is attached to the ground and the upper layer (cortex). Both layers of Briareum violaceum colonies are deep purple due to the colour of the small skeletal structures (sclerites).

Behaviour

Sessile; Suspension feeder

Method of reproduction

Briareum have female and male colonies, and are ‘external brooders’, meaning the sperm are released into the water to fertilise the eggs within the mother colonies. The fertilised eggs develop into larvae inside mucus pouches on the surface of the mother colonies. The brooded larvae often sink to the bottom and settle within a few meters.

Habitat

Marine

Briareum is common in a wide range of habitats, but seems to prefer turbid water or shaded surfaces in clearer water.

Distribution

Found in shallow tropical waters of the Indo-Pacific, but particularly common in the upper 10 m on fore-reefs.

Life Cycle

Sperm, but not eggs, are released into the water, generally a few hours after sunset.