Echinodermata



Animals in this phylum have certain characteristics that group them together. Animals in this phylum have five-fold symmetry. This means that their bodies are mirrored five times. The sea star, for example, has five arms and in the middle of there body is their is a mouth (which also serves as the anus) and five jaws that surround the mouth. This makes the sea star identical on all five sides. Another characteristic of echinoderms is their habitat. Echinoderms live at all sea levels, but only in salt water. These animals are marine animals, and all though at a glance some of these animals may seem totally unrelated, they are. There are many characteristics of echinodermata

Two well known classes in the phylum of Echinodermata are echinodea and ophiuroidea. The class echinodea includes animals such as sea urchins. Sea urchins have long, sharp spines. Sea urchins eat algae and are hunted by larger creatures like sea otters, wolf eels, and triggerfish. They have a five-fold symmetry when they become adults, but as larvae they are bilateral. The sea urchin has tube feet that are attached to some spines. Urchins also have a water vascular system along with a hemal system. Urchins do not have brains, but nervous systems that control their movements.

More common classes are Asteroidea, Holothuroidea, and Echinold. An example, of Asteroidea would be a star fish. A star fish has a calcified skin that protects itself from predator that might want to eat them. This calcified skin was many different striking colors that camouflage them in the ocean or scare a way attackers. These star fish live in brackish water and not fresh water. The sea cucumber falls under the Holothuroidea class. A Sea cucumber eats small particles like algae or waste materials. They will gather the food in their tubes of the tenacles that around the Sea cumber's mouth. Sea cumbers like to live near or on the ocean's floor and sometimes they bury themselves under the sand. A sand dollar would fall under the Echinoid.. Sand dollars are round and flattish which looks like a large coin. Many people on the beach look for the sand dollars that wash up on the beaches. They have a five-pental design that looks like a small starfish. One can find all these animals at the sandy beaches and in the wide blue oceans



Ophiuroidea includes animals like brittle sea stars. These stars are similar to sea starts, but their appendages are longer and thinner, hence the name brittle. They are easy to break of, and sometimes they break off purposefully for reproduction. If the part broken off is long enough, a whole new sea star can grow off of it. Arms also break as a safety defense. If brittle sea stars are attacked, they can break off an arm, escape, and eventually grow more. The sea star’s mouth also serves as an anus, meaning the food goes in where the waste comes out.

The phylum Echinodermata is so evolutionarily successful because the animals in that phylum have unique characteristics that protect them from other predators. Sea urchins have spiny skin to fend off predators from eating them. Sea stars have hard, tough skin to protect itself from sharp object or other predators. Also, when sea cucumbers get cut or have an open wound, they release these red stringy things that scare off predators. Those red things are the guts of the cucumber. Because of these unique defense mechanisms, the animals in the Echinodermata phylum have become very evolutionary successful.

Helpful Links: [|Starfish (Sea Stars), Starfish (Sea Star) Pictures, Starfish (Sea Star) Facts - National Geographic] [|Sea Cucumbers, Sea Cucumber Pictures, Sea Cucumber Facts - National Geographic] []

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