The common sea star (Asterias rubens) is one species out of about 1,600 species of sea stars worldwide. This species is normally purple in coloration but can range in shades from red, to pink, to orange, depending on the type of food the sea star is eating. Sea stars are carnavores and favorite prey includes mussels and oysters.
Like sea urchins, sea stars are in the Phylum Echinodermata, which is why they are more properly called sea stars rather than starfish. Echinoderms exhibit radial symmetry. All common sea stars have five arms, but some sea stars have many more, some up to 40.