Nine-Armed Sea Star

by Kyle Sweet, The Sanctuary Golf Club, Florida Master Naturalist

Recently, I was reminded just how rough the waters along the beaches here can be. A strong cool front pushing through in mid-December brought about the largest waves that I’ve seen in a long time. The sound of the water and wind could be heard from far away and as we walked up to the beach we could see that the sea yields all types of creatures seldom seen except during these events. One that we saw this time and I’ve seen on numerous occasions throughout our area is the Nine-armed Sea Star.

Sea Stars belong to a group of animals whose name means “spiny skin” and includes sea urchins, feather stars, sand dollars and sea cucumbers. The Nine-armed Sea Star, Luidia senegalensis, is a tropical species of sea star native to the western Atlantic Ocean. It is found around the coasts of Florida, the Caribbean Sea, Gulf of Mexico and along the coast of South America as far south as southern Brazil. It’s typically found in deep waters but they move about and rough seas can bring them into shallow waters all along our coasts.

It has long, slim, tapering arms attached to a small, circular central disc and grows to a diameter of 12-16 inches. It has tube feet without suckers and the mouth of the sea star is at the center of the disc. Interestingly, Sea Stars have an eye at the end of each tentacle and have the ability to re-generate lost or broken appendages.

This sea star, like others, is both a predator and scavenger. It’ diet consists of mollusks, small crustaceans and polychaete worms, which are small, bristled, segmented worms that crawl and burrow along the ocean floor. The Nine-armed sea star also buries itself in the ocean floor substrate, typically sandy for this sea stars habitat, and engulfs mouthfuls of sediment. It filters the sediment through oral spines, extracting and feeding on detritus, which is organic material that accumulates on the ocean floor, and other small organisms.

Other varieties of sea stars that you might encounter along our barrier island beaches include the Common Comet Star, Mud Brittle Star, Reticulated Brittle Star and the Common Blunt Arm Star. A walk along one of our beautiful beaches following or during some rough waters would be the best time to find any one of these interesting creatures. A photo and a little research will be a fun way to learn more about your find. Please never remove anything from the beach, whether dead or alive as our ecosystem relies on our natural system to be protected throughout the islands.