Brittle stars

Brittle stars are starfish built the other way round: a small, neat central disc, usually one and a half to three centimetres across, with five thin, flexible, whip-like arms that are clearly separate from it rather than merging into it. The common Maltese species, Ophioderma longicauda, has a smooth-looking disc, often dark chocolate, olive or reddish-brown, sometimes finely mottled, and long banded arms that can give a span of fifteen to twenty-five centimetres. A second regular is Ophiothrix fragilis, much bristlier, with arms covered in fine glassy spines and colours running from orange to purple.

By day they are almost always hidden, packed into crevices, under loose boulders and slabs, and among the rhizomes at the edge of a Posidonia meadow, from a couple of metres down to a hundred. Lift a rock in the shallows at Ċirkewwa or Xlendi and you will often find several jammed underneath, which is exactly why you should put the rock back the way it was.

They do not walk on tube feet like a true starfish. They row, whipping two or three arms forward and dragging the disc after them in a surprisingly fast, spidery scuttle that is worth seeing at least once. At night they emerge, and the bristly kinds climb up onto sponges, gorgonian stems and wreck railings to hold their arms into the current and comb food particles out of the water. The name is earned: a grabbed arm snaps off on purpose, and grows back over the following weeks.