Class Asteroidea

Order Valvatida

Family Goniasteridae


Ceramaster patagonicus (Sladen, 1889)


Broadly pentagonal, rigid, body flat or occasionally swollen. Aboral surface with small flat-topped plates. Arms and disc bordered by large marginal plates. Yellow to pink-orange, no red patches. To 16 cm (6.3 in) across.


Bering Sea to Cape Horn, South America; 5 to 245 m (16 to 1,785 ft). The shallow record is from the Knight Inlet sill, BC.


This species was first described from the trawled collections of the research vessel "Challenger" in the Straits of Magellan, near Patagonia—hence the name. Common in BC fjords. Eats sponges, including the CLOUD SPONGE Aphrocallistes vastus and the CHOCOLATE PUFFBALL SPONGE Latrunculia (Latrunculia) austini The COOKIE STAR is usually larger than the ARCTIC COOKIE STAR and is never red. This star is also much more common than the ARCTIC COOKIE STAR and is found throughout the Strait of Georgia, especially in mainland fjords such as Jervis Inlet and Knight Inlet. It is not uncommon to see several on a single, moderately deep dive in Agamemnon Channel, at the entrance to Jervis Inlet.

In lab experiments I observed that when attacked by a MORNING SUN STAR (Solaster dawsoni), a COOKIE STAR puffed itself up and did not attempt to escape by running away from trouble (a doubtful strategy since the COOKIE STAR is so slow). Later, I found the MORNING SUN STAR with its rays curled far back over its aboral surface, the stomach everted and the tube-feet extended. It was almost as though the attacker had been poisoned. The MORNING SUN STAR recovered in two to three days and attacked again, with the same results. Although four COOKIE STARS were held for over two months in an aquarium with several hungry MORNING SUN STARS, none was ever eaten. It seems that the COOKIE STAR has some sort of chemical defence that is very effective against sea star predators. But exactly what this compound is and how it works is unknown.