Echinodermata are a phylum of marine animals that live in fresh water. Fully grown animals from this phylum can be recognized by their radial symmetry (usually 5-pointed). Echinoderms are found at every ocean level, from intertidal zone (on the surface during low tired) to the abyssal zone (deeper bottom floor part). Echinodermata phylum contains about 70,000 living species, making this the 2nd largest group of all animals after the Chordates. They are also the most extensive phylum that is missing any land and/or fresh water representatives.
The phylum Echinoderms means "spiny-skinned" in Latin. There body shape is contains 5 or more arms (Most of them that are grouped by: 2 left, 1 middle, 2 right). Each arm are equal to the other and have a separate copy of organs. But they do not have a heart, eyes or brain but some special stars such as brittle stars seem to have sensitive tips on their arms. As to their skeletal and muscle system, echinoderms have tentacle-like structures that are called "tube feet" with suction pads that are situated for what their extremities bring them. As their tube-feet presses against an object in motion the water is withdrawn from them, resulting in a suction effect. This shows how the muscular system also relates to how they work and their body shape.
Starfish (Echinodermata Phylum)
Asterias Star Fish (Echinodermata Phylum)
Starfish and sea stars like this are known as echinoderms that are from the class Asteroidea. Starfish similar to other echinoderms have skeletons that consists of small calcareous (Calcium Rich) ossicles, also known as bony plates. In order to move these bony plates they use a system known as water vascular system. In order for them to use their muscles from their muscular system they mainly use their tube feet and press them against a moving object, as a result water is withdrawn from them and makes a suction effect. Later when water comes back into the canals, suction is then released. This results make locomotion very slow but this is how their muscular system relates to their movement.
Holothurians/sea cucumbers (Holothuroidea of Echinodermata Phylum)
Sea cucumber (Scientific Name:
Bohadschia argus) with Cuiverian threads
Holothurians do not contain a distinct special spiral symmetry such as the star fish but instead they are bilateral. Holothurians are also known as sea cucumbers. Their name shows that they are cucumber shaped with an elongated, , muscular, and flexible body with a mouth at one end and the anus (bottom half) at the other side. Near the mouth there are numbers of tentacles used for food collecting. Sea cucumbers are seen in many different sizes, ranging from small (few centimeters) to long snake-like species that may reach up to 6 3/4 feets. With this amazing insight it is just a positive attitude to these wonderful species. Their muscular system that barely exists is simple and basic. They wiggle and crawl around at the bottom of the ocean/sea.
Heart Sea Urchin (Maretia Planulata)
Sea Urchins have a body of symmetry just like any Echinoderms. They do have an external protective skeleton and a jaw located towards the center called an Aristotle's lantern. The mouth has a complex group of muscles and plates that surround the circular opening. The anus is actually located on the top surface of the animal even though it does not sound so. A few sea urchins have a spherical bulb-shaped cloaca that stores little materials that are extended from the anus (anal) opening. These sometimes look like pointy threatening pieces that can be taken out from the shell. Sometimes these spines can be poisonous while some are harmless. The muscle in the mouth also have plates that surround the opening to help movement to feed itself.