Common Name: Ochre Sea Star

Scientific Name: Pisaster ochraceus

Kingdom: Animalia

Phylum: Echidermata

Class: Asteroidea

Order: Forcipulata

Family: Asteroidea

Genius: Pisaster

Species: P. ochraceus



Pisaster ochraceus is better known as the Ochre Sea Star. Its size ranges from 10-25 cm long. Their colors range from purple to orange and then from orange to brown. It depends on the temperature of the water. The amazing thing is that it stiffens its tissue when there are tides and to protect itself from predators and such things. You can tell it’s an Ochre Sea Star because of its colors and the fact that it has five rays that move frequently under water. Some things that'll help it do well in the ecosystem are their suction cups, which will help it move through the water. The water vascular system acts as a hydraulic system. It lets a liquid out of its tube feet that moves it when it’s not being moved by tides. It uses its suction cups to direct itself. It can pry shells open to eat the animals that are inside them. They are found in the cold waters by the North Pacific Ocean and continuously into Alaska and along some coasts of California, which is very weird because most sea stars stay in warm waters instead of cold.


There is no exact number for the population because it has differed for a long time. Some of the reasons why it has changed so much are El Nino, fishing shops, souvenir shops, and most of all people finding it on the beaches. The reason for El Nino is because all the waves made the water temperature warmer so the starfish soon died. Fishing shops and souvenir shops are also a problem because people have found them and caught them. The biggest reason of all is because people constantly find them laying on rocks, or in the water. So as you can tell, their population is shrinking. Save the sea stars!


The sea star is a predator because it has few natural predators, and it's a carnivore. They usually eat mussels but if they can’t find any they'll eat small crabs or crustaceans. Some can even eat a whole mussel bed. First, they'll pry open its shell. They have a mouth that brings out its stomach and digests it inside the shell. They can do this because some of their prey is too large for them to swallow. This is one of their advantages. They also have to have very strong arms to open shells. The only organism they compete with for their food is the people, such as fishermen. The only known predator the Pisaster ochraceus has are the sea lions and seagulls. The strangest thing is that the sea lions only eats its rays. It takes up to a year to grow them back though. The seagulls usually can’t find them so they aren’t as much as a threat. The biggest predator is us. Even though we don’t eat them we find them or buy them and it is making their population go down.


The way that they protect themselves is they stiffen their tissue or hide under a rock. That it is a well-developed animal and it has little hardships, other than us. We are its biggest enemy and we should stop. The interesting facts that I found were that some fishermen were mad because the sea star was eating all its mussels and so they caught some and cut them into the half. They thought that would kill them but it doubled the population. Another interesting fact I found is that they have 5 eyes on each of its rays, but it is blind. Those are just light sensors. I think that is so cool.


Author: Raquel T

Published: 02/2008



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