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Echinoderms

Echinoderms. By: Jaime Acevedo & Matthew Martinez. Skin & Skeleton. H ave a mesodermal skeleton composed of calcareous plates or ossicles.

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Echinoderms

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  1. Echinoderms By: Jaime Acevedo & Matthew Martinez

  2. Skin & Skeleton • Have a mesodermal skeleton composed of calcareous plates or ossicles. • Complete skeletons are rare because they quickly disarticulate once the encompassing skin rots away, and in the absence of tissue there is nothing to hold the plates together. • The epidermis itself consists of cells responsible for the support and maintenance of the skeleton, as well as pigment cells, mechanoreceptor cells, which detect motion on the animal's surface.

  3. The Water Vascular System • This is a network of fluid-filled canals that function in gas exchange, feeding, and secondarily in locomotion. • Consists of a central ring, the hydrocoel, and radial ambulacra stretching along the body or arms. • Tube-feet are extensions of the water vascular system which poke through holes in the skeleton and can be extended or contracted by the redistribution of fluid between the foot and internal sac allowing movement and wafting of food particles.

  4. Reproduction • Sexual reproduction • Echinoderms, are able to reproduce at around 2 to 3 years of age. • To reproduce, the female releases the eggs into the water and so does the male, then when these two meet fertilization takes place • An other possibility of reproduction includes, species such as the feather star, being able to hold the eggs in a pouch until the sperm cells happen to find them. This same technique is used for other species expect they carry the eggs in the side of their mouth, stomach, or on body cavities. • Asexual reproduction • This is possible within the organism itself, such as some type of sea stars which have the ability to regenerate almost every part of their body that has been lost by regenerating them asexualy.

  5. Normal life • Feeding • There are grazers, deposit feeders, or passive filter-feeders, there are also active hunters such as sea stars. • Crinoids use a large net to trap any particles of food that have been pushed along by water currents and then the Crinoids trap this particle and send it to the mouth. • Other Echinoderms can graze over surfaces such as algae. • The sea star being a hunter traps the animal with tits legs, then when trapped in these the sea star uses minimal effort to keep it in place until the pray gets to tired to try to escape, and this is when the sea star feeds.

  6. Ecology • Echinoderms can help the ecosystem largely • Sea urchins can bore onto rocks which has the rock release minerals into the water • Others can prevent algal mats from growing on coral reef which helps the organisms living in the coral reef be able to obtain their food. • Echinoderms can also provide places to live for other organisms such as the sea cucumber, and they also obviously support the food web.

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