These purple and orange sea stars are from the genus Pisaster. They're common along the Pacific Coast, and are the ones you will usually see on pilings or in tidepools at low tide. They are carnivores who eat by pulling shellfish apart with their hydroponic tube feet. They are part of a group named Echinoderms, or Spiny Skins, and you can feel the rough bumps that make a white pattern along the top of the animal. Sea stars are some of my favorite marine creatures.