Echinoderms

Echinoderms are not plants, but sea creatures. They are those creatures are known very widely throughout the world, and have been featured in so many great and poor films that when their names are said or identified, mostly everyone will not even know that those invertebrates, for example, starfish, are part of a bigger class, known as Echinoderms. Echinoderms have been dated to go back to the Cambrian Period, which occurred about 490 to 543 million years ago. The Cambrian Period was in a period known as the Ordovician Period, along with the Silurian Era. The Cambrian Period is greatly known as the point in life where most of the major groups of animals had appeared. The Cambrian Period is known as the “Cambrian Explosion” because of the relatively short time in which the diversity of the forms began.

There are around five different #|classes of Echinoderms. They are: the Sea Urchins and Sand Dollars, Brittle Stars, Sea Cucumbers, Sea Stars, Sea Lilies and Feather Stars. The first class is the sea urchins and the sand dollars. The sea urchins and sand dollars contain large, solid plates that create a box around their internal organs to protect them. The second class, Brittle Stars, is extremely encountered around coral reefs. They have flexible arms and can move around quickly to escape their predators. When attacked, they shed an arm to distract their predators and are given an open window of escape. The third class, Sea Cucumbers, is invertebrates that have the appearance of moving pickles. They remain on the ocean #|floor with the help of their tube feet and go around sucking up matter of animals or plants. The fourth class, sea stars, is very well known as starfish. They move slowly around the ocean floor and prey on bivalves. The last class, sea lilies and feather stars, is invertebrates that are filter feeders and have long, feathery arms, which are the oldest types of Echinoderms. - Sea Urchins - Sand Dollar - Brittle Stars - Sea Cucumbers - Sea Stars - Sea Lilies - Feather Stars

In general, there are around four characteristics for Echinoderms. The four are: spiny skinned, an internal skeleton, a water vascular system, and tube feet, which are like suction cups. The water vascular system is what carries out the body functions in mainly all Echinoderms, such as respiration, circulation, and movement. Tube feet are suction cup like structures that always have a sucker in the end. A tube foot is what lets the Echinoderm anchor itself to the bottom of the ocean so that they don’t go floating away in the strong current that the ocean has within. Their internal skeleton is made up of hardened plates of calcium carbonate. Finally, if you ever touch the skin of an Echinoderm, like of a starfish, you will feel its spin skin because the skin is right above the internal skeleton.

Echinoderms can reproduce both asexually and sexually. Asexual Reproduction is when the body separates into two or more parts, also known as fission, and then the parts that are separated from the other, begin to reform. In order to do that, they would need a cell wall so they can seal the wounds, for when they split apart. Also, they can only regenerate if there are still body parts that are lost in pieces. Now, in Sexual Reproduction, the gametes of both the male and female invertebrates, are released into the water where the sperm and the eggs are brought together and the egg becomes fertilized by the sperm. Then, since the larvae have bilateral symmetry, they stay afloat a while longer and then sink to the bottom of the ocean floor, where they develop as adults and contain a five-part radial symmetry. 