April 27, 2018
This deep-sea mud star, Dytaster insignis, is a species which occurs in the true abyss, 2,515-3,530 meters (8,250-11,580 feet)! Although this individual was observed on the surface, it and other related “mud star” species are often seen buried just below the surface of muddy or sandy bottoms. This and related species are commonly collected with their disks engorged with mud. They have swallowed the sediment in order to devour potential snails and clams as well as other small organisms.
The unfurled tube feet are quite different from the tube feet that one might observe on a sea star in the rocky intertidal. The tube feet on these stars are pointed, rather than tipped with a sucker or a flat tip. These pointed tube feet, in conjunction with spines around the bottom edge of the body, assist these species in digging into the mud. The sharp spines around the edge also protect the star against predators.
Text contributed by Chris Mah, Smithsonian Institution, National Museum of Natural History.