Northern Sun Star, Solaster endeca

The northern sun star (Solaster endeca), also known as the purple sun star or the smooth sun star, is a species of starfish that is classified within the Solasteridae family. It can be found in the North Sea and the Atlantic Ocean with a range that includes coastlines of Greenland, Canada, and the United States. It prefers a habitat in areas with adequate to heavy shelter and muddy or rocky sediment, at depths of up to 1,480 feet.

The northern sun star is large, reaching a diameter of 7.9 inches and a length of about sixteen inches from arm tip to arm tip. It holds between seven to thirteen arms, although nine to ten arms are more common. It can range in color from pinkish purple to greyish cream, while the underside is typically paler in color. Its body is covered in calcareous plates that hold numerous spiny paxillae. The undersides of the arms hold numerous tube feet, which can sometimes be seen when the tips of the arms curl upwards.

The northern sun star, like other starfish species, is a predator that feeds mainly on bivalve mollusks and other starfish species. Its diet does vary depending upon the area of its range, with populations in the Pacific feeding on invertebrates like sea cucumbers. The breeding season varies depending upon the area, occurring in the spring months in Britain. Females release their eggs into the water first and after about a week, males release their sperm and eggs are fertilized, creating small larvae. These develop in the water column for about eighteen days, after which they float to the sea floor and undergo metamorphosis into young starfish.

Image Caption: Solaster endeca, the purple sun star, family Solasteridae. Credit: Georges Jansoone/Wikipedia (CC BY 3.0)