Among the most beautiful of echinoderms, C. papposus is a bright spot of color in North Atlantic and Pacific waters. It can be readily recognized and differentiated from other sea stars in that it has several more than the standard number or tube feet (five). (Hickman and Roberts, 1995)
Unfortunately, information regarding the economic importance of C. papposus and its value to humans is either not well-studied, not well-documented, or simply inaccessible. As an aggressive predator high on its food web and as an agent of dispersal of both its competitors and prey, C. papposus clearly has a significant impact on its ecosystem.
In its habitat, C. papposus is considered to be the dominant predator, along with Solaster endece, another species of predacious sea star. As a dominant predator, C. papposus plays an important role in determining community structure. (Himmelman and Dutil, 1991) Its abundance and frequent predatory activity suggests that it belongs to an important predatory guild. C. papposus has often been observed feeding on urchins, as well as on numerous other invertebrates, including echinoderms, bivalves, cnidarians, and tunicates. (Coleman, 1991) Cannibalism in C. papposus is rare, observed only after long starvation in captivity. (Sloan, 1984)
North Atlantic and Pacific Coasts: (Himmelman and Dutil, 1991) One can find C. papposus from Alaska to Puget Sound, from the Artic to the Gulf of Maine. (MConnaughey and McConnaighey, 1985) It is common in British waters and in eastern Maine and can often be found in the lower intertidal zone from the Eastport area northward. (Hayward and Ryland, 1995)
Biogeographic Regions: atlantic ocean (Native ); pacific ocean (Native )
Crossaster papposus is found on rock bottoms, ranging from the low tide line to approximately 1080' (329m) deep. (McConnaughey and McConnaughey, 1985) It is tolerant of strong sunlight. (Coleman, 1991)
Aquatic Biomes: coastal
Crossaster papposus ranges from 8" to 14" in diameter. It has many arms (between 8 and 14) the length of one-half its radius. It is scarlet on top with concentric bands of white, pink, yellow, or dark red, and it is white on the underside. Its entire upper surface is sparsely covered with brushlike bristles. (McConnaughey and McConnaughey, 1985) These bristles, called pseudopaxillae, consist of bundles of fine spines atop short stumps. The mouth area is bare, and it has two rows of sucker-tipped sensory tube feet. (Gosner, 1978)
Other Physical Features: ectothermic
Crossaster papposus, like most sea stars, has separate sexes, and fertilization is external. (Hickman and Roberts, 1995) Sexual reproduction produces lecithotropic larva in late winter. One-year-old individuals measure 1.8 to 4.0 cm in diameter, and there is a 2 cm annual growth increment during the following few years. (Himmelman and Dutil, 1991) Juvenile C. papposus tend to prefer sediment bottoms of the sea. Upon growing to 5cm in diameter, C. papposus migrates to shallow water (4-8cm in diameter) and then, with increasing size, it gradually moves to greater depths. (Himmelman and Dutil, 1991) Like other sea stars, C. papposus can regenerate injured or missing arms, as long as a portion of the central disc, where the arms converge, is intact. (Hickman and Roberts, 1995)
