Nine-armed sea star

The nine-armed sea star has long, slim tapering arms attached to a small circular central disc. It grows to a diameter of about 30 to 40 centimetres (12 to 16 in). The aboral or upper surface has a patchwork of closely packed spiny plates. The square ones near the edge of the arms are cream coloured and the irregular ones in a band running down the middle of the arms are grey. The margins of the arms are fringed with short white spines. The oral or underside of the sea star has further small white spiny plates down the edges of the arms and a central band of translucent, orange tube feet. Like other members of its genus, it has tube feet without suckers. The mouth is at the centre of the disc and there is no anus, undigested food fragments being expelled through the mouth.