#24 Starfish

#24 Starfish

(Pisaster Ochraceus)

Common Name: Purple Sea Star/Ochre Starfish

Description

- Purple color

- About the size of a man's hand 

- 5 arms about 7cm in length

- The arms are arranged around a central disk

- There surface is rough and contains several small spines(ossicles) that are arranged in a net-like pattern on the central disk

- They have tube feet with suckers on the ends which allow them to attach to a wide variety of surfaces

Taxonomy

- Kingdom: Animalia 

- Phylum: Echinodermata

- Class: Asteroidea

- Order: Forcipulatida

- Family: Asteriidae

- Genus: Pisaster

- Species: P. ochraceus

Ecology

- Pisaster has been described as a keystone species, they only have a few predators (sea gulls, otters).

- They can be found in great numbers on mussels beds and on rocky shores in crevices and under rocks.

- Pisaster starfish have been hit by Sea Star Wasting Disease, which is killing many starfish on the pacific northwest. The disease leaves legions on the ectoderm followed by tissue decay, which leads to fragmentation of the body and then death. The cause is still unknown at this point. However scientists believe it is due to environmental factors.

- If the disease persists and a cure is not found there will could be no sea stars left within a few years.