Gorgonocephalus eucnemis is a species of basket star in the class Ophiuroidea. It’s located in circumpolar marine environments within the Northern Hemisphere. The scientific name for the genus comes from the Greek, “gorgos” meaning “dreadful” and “cephalus” meaning “head”, and is in reference to the similarity between these basket stars and the Gorgon’s head from Greek mythology with its writhing serpents for hair. The specific name “eucnemis” is from the Greek “good” and “boot”.
This species has a central disc up to 5.5 inches across with five pairs of arms that branch dichotomously into smaller and smaller subdivisions. The coloration is varying shades of white and light brown frequently with a darker disc. It has an endoskeleton of calcified ossicles and is blanketed in a fleshy layer of skin providing it with a rubbery appearance. The arms are covered in tiny hooks and spines which can be utilized to grip and manipulate particles of food.
Gorgonocephalus eucnemis can be found within the Arctic Ocean and northern portions of the Atlantic Ocean as far south as the Faeroe Islands and Massachusetts. It occurs also in the Pacific Ocean from the Bering Sea south to Japan and Laguna Beach, California. It’s mainly found in rocky areas with strong currents at depths down to 6,600 feet but is most commonly found at depths of 49 feet to 490 feet. It’s also found on mud and sandy seabeds in the midst of boulders, sea fans, and sea pens.
This species feeds by perching in an elevated position and stretching out its arms in a net-like fashion that is perpendicular to the current. The branches and branchlets coil and twist, making it resemble an animated bush. It entangles small crustaceans such as the northern krill, copepods, chaetognaths, detritus and jellyfish that come within their reach. The prey that gets trapped becomes the center of a “knot” where it’s immobilized by the secretion of mucus. Additional coiling of the branches brings the food to the mouth which is on the underside of the central disc. Here the branchlets are passed through a comb-like structure which eliminates the particles of food. There’s no anus and any undigested pieces are expelled through the mouth.
Individual basket stars are either female or male. After spawning, the larvae become a part of the plankton and disperse with the currents.
This species is cryptic and stays well hidden during the day. It’s protected by the toxic nature of the sponges where it creeps around but is occasionally eaten by fish and crabs. It’s been observed to return to a particular located regularly.
It’s often found residing in association with sponges and soft corals in the genus Gersemia, hiding under them or in the folds of the sponges during the day and utilizing them as elevated platforms for finding prey during the night. In Puget Sound, juvenile Gorgonocephalus eucnemis have been found to be living and seemingly feeding inside the pharynges of Gersemia rubiformis polyps, emerging only when sufficiently grown to fend for themselves.
Image Caption: Gorgonocephalus eucnemis. Credit: NOAA/Wikipedia