Pin-cushion Sea Star

Appearance

A mature ''C. novaeguineae'' is pentagonal in shape with an inflated appearance and much-abbreviated arms. It can grow to a diameter of 30 cm . Rows of tube feet are on the underside, and it has a central mouth. The colour is very variable and includes a mottling with darker and lighter shades of fawn, brown, orange, yellow and green. The armoured body wall is made of calcareous ossicles which are supported internally by pillars which buttress the ambulacra. The armouring contains pits into which the tube feet can be retracted. The body cavity is filled with water. Small cushion stars are very different in appearance. They are star-shaped, with five short, broad arms and a low profile. As they grow, the inter-arm areas fill in and expand relative to the tube-feet areas, and the arms get shorter relative to the disc which becomes inflated and more massive.

Distribution

''C. novaeguineae'' is found in the Indian and Pacific Oceans. Its range extends from Madagascar and the Seychelles to the Philippines, New Guinea , Australia and Hawaii.

Behavior

''C. novaeguineae'' feeds on detritus and small invertebrates, including stony corals. It can be kept in a reef aquarium of sufficient size stocked with suitable corals on which it can feed.

Habitat

A number of organisms live in or on ''C. novaeguineae''. The small shrimp ''Periclimenes soror'' lives as a commensal hiding under the cushion star. ''Astroxynus culcitae'', ''Stellicola oreastriphilus'' and ''Stellicola parvulipes'' are copepods which live parasitically on the outside of the cushion star. The star pearlfish sometimes lives as a commensal inside the cushion star, working its way into the large body cavity through an ambulacral groove and emerging periodically to feed.