Investigation of pedicellariae distribution among diverse habitats and genetic lineages of Leptasterias species
By: Elora Chatain
Department: Biology
Faculty Advisors: Dr. C. Sarah Cohen and Dr. Bing Huey
Leptasteria spp. is a species complex of small, predatory sea star found in intertidal habitats along the west coast of North America, from Alaska to central California (Kwast, Foltz and Stickle, 1990; George, 1994; Foltz et al., 1996). Leptasterias occur in rocky intertidal and subtidal habitats, typically measure less than 6 cm from ray tip to ray tip and mature around 2 years of age. Unlike larger sea stars which tend to disperse their gametes via broadcast spawning (Menge, 1975; Pearse and Beauchamp, 1986), Leptasterias spp. are limited dispersers – larvae are brooded until they reach the juvenile stage, at which they crawl away from the mother (George, 1994). The resulting limited transport of individuals across local populations may lead to clade differentiation or local adaptation, due to decreased gene flow among population (Strathmann, 1985; Kwast, Foltz and Stickle, 1990; Foltz et al., 1996; Melroy, Smith and Cohen, 2017). The potential for Leptasterias to form ecotypes based on wave-exposed and wave-protected microhabitats has been observed. Many lineages within the Leptasteria genus have an unresolved taxonomic status. This study will observe morphological characteristics of the different species in the hope of discovering a difference and refining the differentiation of species. In fact, it has been observed that Leptasterias spp show presence of crossed pedicellaria. They consist of small claw-shaped appendage with movable jaws. Nevertheless, their number and distribution vary, and these variations are only very little studied in the current literature. Our study seeks to find out if such a difference is visible between the species L.pusilla and L.aequalis. The distribution of these pedicellaria could also inform us about their role in the sea star life.