You echinoderms are marine animals like the starfish, sea biscuits and sea urchins, that we can see when we visit a beach.
Biologists say that the echinoderms they are free-living, that is, they live free in sea water, with the exception of the sea lily, most of which live attached to rocks at the bottom of the sea. At starfish are easily found, moving on the ocean floor, as are the sea urchins. Sometimes some hedgehogs are found near rocks, where they dig holes that will provide shelter.
The word "echinoderms"comes from the greek and means horses = thorn; dermatomes = skin, that is, the echinoderms they are animals that have their whole body covered with thorns. These, in addition to having a defense function, also act in the animal's locomotion.
In the picture we can see a sea urchin with all its spines
These animals have a very varied diet. sea urchins like to feed on seaweed and small animals. already the starfish they feed on oysters, mussels, other echinoderms, corals and sea anemones. These animals breathe through small gills that are found around the animal's mouth.
You echinoderms they have, in most species, separate sexes, with external fertilization, that is, male and female release their gametes (sperm and eggs) into the water for them to be fertilized. We say that development in this animal is indirect, because before it becomes an adult it goes through one or more larval forms.
In the image we can see the starfish larvae, which after a while will undergo metamorphosis and become young starfish
You echinoderms have a very curious characteristic: the ability to regeneration. Because they have this ability, these animals are able to regenerate parts of the body that have been damaged. You sea urchins, for example, continually regenerate their thorns; and starfish can regenerate one or more lost arms.
At starfish they have a central disc where their nervous system is located, which is very simple. If the starfish is split, it can turn into another star, as long as there is a part of the central disk in the part that was removed. These echinoderms have very simple eyes located at the ends of each arm, which are only able to perceive luminosity.
Starfish are echinoderms that have five arms.
Some animals echinoderms are called star serpent, sea serpent or yet pothole, which look a lot like the starfish because of his long, thin arms.
Other animals that are also echinoderms they are the sea cucumbers, sea biscuits and sea lilies, which can be seen in the figure below.
In the figure we can see other species of echinoderms
By Paula Louredo
Graduated in Biology
