Slender Starfish, Astropecten bispinosus

The Slender Starfish (Astropecten bispinosus), is a species of sea star in the Astropectinidae family. This species lives only in the Mediterranean Sea and prefers sandy seabed near meadows of Cymodocea nodosa. It is found at depths between 8 and 400 feet. While sandy seabeds are preferred, it can also be seen on muddy and gravely mobile seabed as well. It remains buried during the day.

This sea star has very narrow and high superomarginal plates with a bare area on the vertical face (between the superomarginal and inferomarginal spines). Each plate has a single very long, sharp, conical spine usually white in color but sometimes yellow or orange. This spine is always placed on the top internal edge of plates so there aren’t any bare area on top of the plates. Each arm has an upper limit of 77 superomarginal plates, with 40 to 60 being more common. The superomarginal spines between the arms are often longer than the others. The inferomarginal spines are long, flat, not pointed, usually kept parallel and well separated.

The Slender Starfish has a very small disc and very long thin arms. The aboral (back) side has uniform color and can be dark green, dark brown or rarely light brown-pink. The oral side is light colored, usually white but can also be yellow or orange. This sea star can reach a diameter of 8.25 inches. This species may be confused with Astropecten platyacanthus, but upon closer inspection can be distinguished by differences in the superomarginal plates, and by color.

This creature emerges during the late afternoon from its hiding spot and goes on the hunt for bivalve mollusks, its main food source. It is very active and easy to spot in the late afternoon, but can sometimes be found moving about at night, and seldom in the daytime. It catches food with its arms and then takes to the mouth. The prey is then trapped by the long, moving prickles around the mouth cavity.

Image Caption: Astropecten bispinosus. Credit: Rpillon/Wikipedia(CC BY-SA 3.0)