The Starfish of Hong Kong, Part 2

Blue Linckia (Linckia laevigata)

Blue Linckia via WikiCommons cc-by-sa 3.0

Ranges in color morphs from dark or light blue, but also observed as aqua, purple, or even orange variations throughout the ocean. Grows up to 30 cm in diameter and has rounded arm tips. Some individuals can have lighter or darker spots along their arms. They are typically firm in texture and have slightly tubular arms with short, yellowish tube feet on the underside. It inhabits coral reefs and sea grass beds. They occur subtidally, sometimes intertidally, on fine sand or hard surfaces and move quite slowly .

Cushioning Star (Culcita nouvaeguineae)

via WikiCommons (Shizhao, cc-by-sa-2.5)

The cushion star has very short arms and an inflated appearance, resembling a pentagonal pincushion. Its colour is variable and it occurs in tropical warm waters in the Indo-Pacific. It ranges from Madagascar and the Seychelles to the Philippines, New Guinea, Australia and Hawaii.  It feeds on detritus and small invertebrates, including stony corals.

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The Starfish of Hong Kong, Part 1

Crown-of-Thornes (Acanthaster planci)

Crown-of-Thornes starfish

The crown-of-thorns starfish is a large starfish with many arms that preys on hard coral. Its name comes from the venomous thorny spines covering its upper surface – meant to resemble the crown of thorns put on Jesus before his crucifiction. This is one of the largest starfish and has a very wide distribution in the Indian and Pacific Oceans at tropical and subtropical latitudes where coral reefs or hard coral communities occur.

The venom of the starfish contains so-called asterosaponins which have detergent-like properties. The brittle spines can perforate the skin of a predator or unwary diver and tissue containing the venom is lodged into the resulting wound. In humans this immediately causes a sharp, stinging pain lasting several hours, with persistent bleeding aided the venom as well as nausea, tissue swelling lasting for a week or more. Breaking of the spines means they become embedded in the tissue where they require surgically removal.

Peppermint Sea Star (Fromia monilis)

The peppermint sea star can grow to a diameter of about 30 centimetres. Its arm tips and the central disc are bright red, while the other parts are paler, forming large plates. The color, plates and other features can be very variable and identification from photographs can be difficult. It feeds on encrusting spongess, detritus and small invertebrates. Occurs in shallow water in rocky environment, at a depth of 0 – 51 m.