Feather stars are so called because their arms look just like feathers. By day they keep curled up but on night-dives you see these pretty animals in their warm colours, with their feathery arms extended.
When food is plentiful, with strong currents carrying large amounts of plankton, feather stars will form large groups. They appear to have no particular predators. Look closely and you will often see another animal - such as a shrimp, crab or fish - living with the feather star.
Photo copyright Tim Nicholson.
Feather star in Middle Reef, Red Sea, Egypt.
Relatives of starfish, there are many different species of feather star. Some species have 5 arms, some 200.
Photo by Jill Studholme.
Feather star in Soma Bay, Red Sea, Egypt.
Also known as crinoids, feather stars have a tenacious grip and anchor themselves to coral, seaweed, sponges and the like. They can swim by sweeping their arms up and down, or crawl slowly on the tips of the arms which are bent right over to hold the body away from the sea bed. They spend most of their time though simply anchored in their chosen location, suspension-feeding.
Photo by David Mark.
Their feathery branches are equipped with numerous tiny tube feet that catch floating food and flick it into grooves which run down each arm. The food is then transported down to the mouth in the centre of the body. Unlike starfish, a feather star's mouth is on the top side of its body.
You find feather stars almost everywhere: in tropical, temperate and polar seas.
Next time you are night-diving it's worthwhile spending some time examining these lovely creatures.
Great British Marine Animals, by Paul Naylor