3.1 BIOLOGY OF THE SEA STAR
Four major species of sea stars can be found in the Gulf of St. Lawrence:
the boreal or northern sea star (Asterias vulgaris), the polar sea star
(Leptasterias polaris), the spiny sunstar (Crossaster papposus) and the purple sunstar (Solaster endeca) (Gaymer et al. 2004) (Fig. 2). Although the focus in
this paper will be on Asterias sp., consideration should be given to the fact that
there are strong interactions between these four species. While A. vulgaris preys
on molluscs and echinoderms including other sea stars (A. vulgaris and L.
polaris ), L. polaris preys mostly on mussels and infaunal molluscs. C.
papposus, on the other hand, preys on a variety of echinoderms (including L.
polaris ), and S. endeca preys solely on sea cucumbers (Gaymer et al., 2004).
These predation differences stress the importance of discriminating between sea
star species during abundance studies.