The starfish is a pretty sea creature, with its swirly-shaped arms dipping out at all angles from the fish. The usual number of arms is 5 or 6, but there are different species of the starfish, and some of those have as many as fifty arms, or rays, as they are called. This gives them a very interesting look, and people are often fascinated when they see a starfish for the first time.
It is an amazing sight
On the tip of each arm there is a tiny eye, and that’s how the starfish, also known as the sea star, sees light and dark. This helps them to detect movement around them and aids in getting food. The starfish’s eye doesn’t contain an iris or cornea, as does a human eye.
A starfish’s stomach
Before getting into the specific food, it would be interesting to know how the starfish eats. On the bottom of the fish, one can find the mouth. This mouth opens into the esophagus and from there goes into the cardiac stomach. The next step is to open into the pyloric stomach.
Yes, the starfish has two stomachs
Some starfish are known to swallow their quarry in one piece, and begin to digest it in both stomachs. In other species, the cardiac, or first stomach has the ability to push itself out of the body and surround, compress, and digest the food. It can also grab prey with the outer cardiac stomach, which is then moved into the internal pyloric stomach, where it is digested.
So, what do they eat?
The foods that the starfish, a predator, eats are bivalves such as clams, oysters and mussels. They also eat any slow-moving fish. Others eat material that has decomposed from plants or animals. It seems that anything within reach is gathered for mealtime.
The Acanthaster planci
The crown-of-thorns Starfish (Acanthaster planci) eats plankton, coral polyps or sponges, and is known as the “infamous” planci. This is because the starfish has the skill to digest food outside the body. It is able then to hunt food that is larger than its mouth would be able to accommodate.
There are starfish from America’s west coast, the short-spined pisaster, that are fitted with a set of special tube feet enabling them to extend themselves deeply into the substrata to pull out the clams or other prey from within. This is yet another way the sea star hunts.
Amazing survival story
There have been reports of some sea stars living for many weeks without food. This happened under artificial circumstances and it was thought that the fish might possibly have been receiving nutrients from different organic matter that had dissolved in seawater.