I am sure you have heard these guys referred to as Starfish most of your life. Well, it seems someone misnamed these beautiful creatures as fish, when in fact they are invertebrates. Sea stars are closely related to the sea urchin and sand dollar. Scientist properly named them Sea Stars due to the fact they are not fish.
They are classified as Asteroidea
The Definition of Asteroidea: the class of echinoderms ("spiney skin") compromising the starfishes, all being unattached, having
(1) a star-shaped or pentagonal body, the rays or arms (usually 5 in number)
hollow and contain prolongations of the coelom and alimentary and
(2) a skeleton of calcareous plates and ossicles somewhat loosely united,
often allowing the arms great freedom of movement, and
(3) a mouth on the lower surface without jaws or teeth, an ab-oral
madreporic plate, and the anus often wanting or function-less
(undigested matter being thrown out at the mouth), and moving by
means of the arms or of long spines on the sides of the arms or by rows
of tube feet that occur in a furrow on the lower surface of each arm.
As a marine animal, the Sea Star uses sea water to pump nutrients through its system instead of blood. However, they are a very carnivores creature with an appetite for clams and oysters. Their unique abilities to consume food outside of their bodies makes them a very effective carnivore. As they approach a victim for dinner, they use their tiny, suction-cupped tube feet pry open the shells and then protrude their cardiac stomachs produce enzymes into the shell and devour their dinner. They feed often based on size not age. They compete with the commercial fisherman. One Sea Star can consume 50 young clams in a week.
With over 2000 species, the most common is the 5 ray Sea Star and the not so common 10, 20 or even 40 ray Sea Stars are out there in our vast ocean, with no fresh water Sea Stars and very few brackish water Sea Stars. As for the Sea Stars calcium, bony skin of striking colors protects, camouflage or scares off potential predators. Purple eyespots at the end of each ray detect light.
By housing their vital organs in their rays, they are able to regenerate a new ray or even an Sea Star from a severed ray. Regeneration requires a central portion of the Sea Star to be in tack to regenerate, however, the Linckia diplax, Sea Star has been witnessed to regenerate a new Sea Star from a ray. Regeneration can take from a couple months to several years and depending upon the cell reformation process. If the process is interrupted the ray may be deformed. By being able to regenerate Sea Stars are sexually and asexually marine creatures. Their breeding season is in the spring and they produce over
Predators of the Sea Star are bottom-dwelling fish and crabs, as well as sea gulls hunting in shallow waters. In the past around 1929, fisherman removed 11 million Sea Stars from Narragansett Bay because they were eating all the oysters. One other predator is the fertilizer industry, odd I know. But they harvest the Sea Stars by tools resembling mops with long strings. The Sea Stars attach to them then they are hauled up and then they grind them up for fertilizer and poultry feed.