Ochre Starfish, Piaster ochraceus, also known as Purple Sea Star, is alive and well in The Sea Ranch. Together with California Mussel, you can say that they were the inspiration for the concept of a "keystone species." Back in 1969, a zoologist by the name of Robert T. Paine studied these two animals and their interaction and argued that they were critical to the cycle of life in the intertidal region. Since then, a lot of other animals have been given the keystone designation, but Starfish was one of the very first. That makes him something of a celebrity.

Don't be confused. Just because his name is Ochre Starfish does not mean that he comes in just one color. In fact, you will see a range of color from orange to purple. They are all the same animal and most of us just call him Starfish (or Sea Star- the name the scientists prefer). His role in the intertidal world is to keep Mussel in check. If Starfish did not exist, Mussel would pretty much completely cover all of the rock surfaces and crowd out all of the other animals that seek to live there. At various times in his development, Starfish feeds on everything from plankton to invertebrates, but, as an adult, he goes after Mussel.

Starfish

Starfish

Starfish

Starfish

Seagull & Starfish

The inner workings of Starfish are complicated and we make no pretense at understanding them, but suffice it to say that he moves on very small feet located on the underside of his body. Anyone who has watched him understands that he is very slow, but everything is relative. He is lightening fast compared to Mussel. He uses his feet to pry open Mussel's shell and then inserts his stomach inside Mussel to digest him. Gross, but apparently very effective. The scientists that watch these kinds of things think that the balance of life on the rocks in the splash zone is just about right.

Obviously, too many Starfish would cause a problem, so Seagull has the job of keeping him in check. Starfish is a pretty big mouthful for Seagull so he has a number ways to cope with the situation. He can pick him up by one of his arms or he can just dislocate his jaw and stuff Starfish inside his mouth. Again gross and again effective. The real worry for Starfish is water pollution. His internal workings requires that he constantly pump clean water through his body. Simply put, polluted water will kill him.

When you next go tidepooling, please step carefully.
Many of those strange things under foot are alive.