Starfish – are colorful organisms that live in the aquatic environment. There are nearly 2,000 different species of starfish, each with its own characteristic size, shape, and color – blue, purple, pink, or orange.
These star-shaped sea dwellers are covered in a multitude of patterns, including stripes, swirls, and even flowers. They can be found in kelp beds, seaweed, coral reefs, and tide pools. Starfish survive only in salt water. In addition, they cannot remain out of water for more than a few minutes.
Starfish are also considered some of the most unique inhabitants of the seas and oceans. Why? Here are just a few facts that will surprise anyone.
Neither fish nor stars
The English name Starfish («star fish») is misleading. Starfish are invertebrates, because they have no backbone, like, for example, sea urchins.
Some of them, by the way, are not even star-shaped. Some species of starfish may have more limbs than the standard five «arms». For example, the National Park Service reports that the starfish known as the crown-of-thorns (Acanthaster planci) has 21 arms.
Instead of legs – suckers with glue
Starfish can move thanks to hundreds of tiny suckers resembling feet. They also use this feature for feeding.
In addition, a glue-like material in these sucker-feet helps them stick to objects such as rocks, so they do not fall off or get washed away by the waves.
They can hold food thanks to the small suckers on the underside of their feet. The glue on them also helps the starfish open mussels and clams.
Regrowing lost limbs
During injuries, for example when they are struck by a rock during the tide, starfish can regenerate severed limbs. Although it may take up to a year, starfish can regenerate their entire body from just a single «arm» and only a fifth of their central disk. Few animals are capable of such a thing!
Starfish have no blood
The circulatory system of starfish consists of water rather than blood. This system, typical of echinoderms such as starfish and sea cucumbers, consists of channels connecting the tube feet, through which seawater circulates inside the starfish’s body. And its nervous system gets nutrients from the filtered seawater.
They are carnivorous
These charming sea dwellers actually eat not only plants and algae. Starfish eat animals such as sick or injured fish, whole oysters, mussels, clams, and even sea urchins.
Sometimes starfish display aggressive cannibalism. A study published in the journal Ecology in 2021 showed that young starfish eat one another.
Their stomach envelops the prey
External digestion – is another feature of starfish. Once their food is caught, they push their stomach out of their mouth and envelop their prey in it. And then they gradually push the prey toward their digestive glands after it has been partially digested.
Scientists have figured out why humanity has still not made contact with aliens
Thousands of eyes
At each of the tips of a starfish’s limbs there is an eyespot. The image that the animals see consists of a single pixel from each of these eyespots.
Starfish have many eyespots on each limb, which allows them to observe everything around them at once .
