Striking Sea Star

This small starfish is star-shaped and has five stubby arms. The aboral (upper) surface has an inflated appearance due to it being covered by a "supradorsal" membrane; this is supported by bundles of spinelets borne on the flat plates that are arranged in a mosaic pattern on the cuticle below. This membrane encloses a supradorsal cavity filled with sea water, which is connected to the water column by a central osculum (aperture), which opens and closes periodically. The membrane has a reticulated pattern of ridges and small conical protrusions. It is patterned in some combination of red, white and brown.

Euretaster insignis is native to the tropical western central Pacific Ocean from the intertidal zone down to about 132 m (430 ft). It is found on coral reefs, rocky coasts, sand and muddy rubble.

The sexes are separate in Euretaster insignis. Instead of being planktonic, the developing embryos are brooded in the supradorsal cavity, and even receive nourishment from the mother in the form of a mucosal secretion from the cuticle; they receive this because their presence irritates the lining of the cavity causing it to secrete the fluid in a process that has been described as "cannibalistic ectoparasitism". The larvae are brooded until they are about 1 cm (0.4 in) in diameter at which time they are liberated as juvenile starfish into the sea.