Echinoderms are a phylum of marine invertebrates that include starfish, brittle stars, sea cucumbers, sea urchins, sand dollars, and crinoids. They are one of the most diverse groups of marine invertebrates and play important ecological roles from the near-shore environment to the deep seas.

They don’t use large muscles working on large body parts like many other animals. Instead they move, feed and breathe with a unique water-vascular system ending in hundreds of water-filled tube feet.

Terms in this set (14) Are Echinoderms and Chordates related. that have a backbone) and other members of phylum Chordata. Nevertheless, DNA evidence indicates that echinoderms and chordates are closely related, with both phyla belonging to the Deuterostomia clade of bilaterian animals.

Why are echinoderms animals even though they have no brain? – They are animals because they are movers and shakers in their domain. In the game of life, they are Earth’s most winning creatures 2. Do echinoderms have heads or faces? – They have no heads or faces 3.

Echinoderms such as starfish (more accurately referred to as sea stars), brittle stars, sea urchins and sea cucumbers do not have a brain or a brain-like organ in their bodies. The coordination of the nervous system is carried out by the nerves that radiate out from around the mouth and down into each arm or tentacle.

Echinoderms also have a spacious coelom (an open, fluid-filled body cavity lined with tissue), large gonads, and (usually) a complete gut.

The digestive system often leads directly from the mouth to the anus. The echinoderms have an open circulatory system, meaning that fluid moves freely in the body cavity. But echinoderms have no heart. This may be due to their simple radial symmetry – a heart is not needed to pump the freely moving fluid.

Whether they advance or retreat depends on the species. While a starfish lacks a centralized brain, it has a complex nervous system with a nerve ring around the mouth and a radial nerve running along the ambulacral region of each arm parallel to the radial canal.

Starfish, also known as Sea Stars, are one of the most beautiful looking animals in the vast ocean. They have a surprisingly unusual anatomy, with no brain or blood, yet are able to digest food outside their body.

Beyond their distinctive shape, sea stars are famous for their ability to regenerate limbs, and in some cases, entire bodies. They accomplish this by housing most or all of their vital organs in their arms.

Reproduction. Both male and female sea stars hold their sperm and eggs in pouches at the base of their arms. They reproduce by free spawning, that means ideally the male and female release their eggs and sperm at the same time. The egg and sperm float until they meet up and the sperm is able to fertilize the egg.

In fact, one starfish may become two if part of the central ring is attached to the part separated from the main body. Some starfish intentionally reproduce this way, by separating their own bodies in half, if the population is dwindling.