INTRODUCING THE AMAZING FEATHER STAR!!
It is the similarities between a bird’s feather and the arms of this animal that gives us its common name, the feather star. They are related to sea stars, sea urchins and brittle stars which we have discussed in previous Creature Features.
They are not the easiest animal to find on a rocky shore but well worth it when you do spot them. When in the open, they move their arms about, extending them in all directions or curling them up over or below their body. If overturned by a wave, they will use these long arms to push themselves over. This range of movement is possible because the arms are not rigid, rather they are made of many jointed segments.
Like a brittle star, a feather star’s arms originate from a central disc but the mouth, tubular feet and anus are all on the top of the disk, not on the bottom. Also, the tubular feet of a feather star lacks the suckers on the end which are found on its relatives. Feather stars you find may not have a full set of arms due to interactions with predators or the environment but, like their relatives, they can regrow lost body parts.
The feather star has an additional set of slender arms, called cirri, which grow on the underside of the disc and are used for walking and hanging on to objects while resting or feeding.
The feathery appearance of the arms is created by the row of pinnules down each side of the arm. The arm and pinnules are covered with tubular feet which help catch food. Feather stars are suspension feeders and their food is suspended in the water and pushed along by water currents. On the menu are members of the plankton community as well as scraps of organic material. When food bumps into the arm it is trapped in a mucus layer and then passed by the tubular feet into a groove which runs along the arm to the mouth. Food is pushed along the groove towards the mouth by microscopic hairs, called cilia.
Feather stars are primarily nocturnal animals. During the day they will seek cover and all you will see of them is an arm or two extended out from their hiding place. At night feather stars come out and feed.
Watch this mesmerising video of a tropical feather star species swimming!!
If you would like to learn more about the fascinating world of feather stars and the huge diversity of life that can be found in your local rock pools please contact Education Director Mandy Robertson on education@dolphinresearch.org.au
