Ochre Sea Star
Ganges Harbour, British Columbia
Conservation status
Secure
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Asteroidea
Order:	Forcipulatida
Family:	Asteriidae
Genus:	Pisaster
Species:	P. ochraceus
Binomial name
Pisaster ochraceus Brandt, 1835

The Pisaster ochraceus, generally known as the Purple Sea Star or Ochre Sea Star, is a common sea star found among the waters of the Pacific Ocean. This sea star has five rays that range in length from 10 to 25 cm. While most individuals are purple, colour variations include ochre, pink, and brown. They typically live in the intertidal like other pisasters, and are easily found during low tide clinging to rocks singly and in large groups.

A study found that Pisaster ochraceus will not be affected by ocean acidification in the same way as most calcerous marine animals. This normally causes decreased growth due to the increased acidity dissolving calcium carbonate. Researchers found that when Pisaster ochraceus was exposed to 21°C and 770ppm CO₂ (beyond rises expected in the next century) that they survived. It is thought that this is because the animals calcium is nodular and so it is able to compensate for the lack of carbonate by growing more fleshy tissue instead.^[1][2]

[edit] References

[edit] External links

• The Biogeography of the Purple Ochre Sea Star (Pisaster ochraceus) San Francisco State University
• Pisaster ochraceus, Walla Walla Washington University
• Pisaster ochraceus, Animal Diversity Web
• Ochre Sea Star, North Island Explorer