Marine Animal Encyclopedia
Cushion Star Culcita novaeguineae
The cushion star looks more like a spineless sea urchin than a starfish; it gets its name from its plump, rounded body. Its arms are so short that they merge with its body and only their tips can be seen. Juvenile cushion stars are much flatter than adults and have a clear pentagonal star shape, with obvious arms. They hide under rocks to escape predators, whereas the tougher adults are relatively safe in the open.
Cushion stars occur in a wide range of colors, from predominantly red to green and brown. The underside has five radiating grooves that represent the arms and are filled with tube feet. If the starfish is turned over, it can right itself by stretching out the tube feet on one side, anchoring them to the sea bed, and pulling. The cushion star feeds mainly on detritus and fixed invertebrates, including live coral. Two other similar species are found in the Indo-Pacific tropics but this one is the most common and widespread.
Cushion Stars Host Live-in Guests
The surface of the cushion star provides a home for a tiny shrimp, the sea-star shrimp Periclimenes soror. The shrimp does no harm to its host and is also found on other starfish. It often hides beneath the starfish and also matches its color to that of its host.