THE WATER VASCULAR SYSTEM THAT CHARACTERISES ANIMAL THAT OCCUR IN THE PHYLUM ECHINODERMATA

Water vascular system is a" system made by many canals branching througthout the body that branch into many section known as the tube feet" (1). Species such as star fish and sea urchins use water vascular system to move from one place to another and they also use this system to feed themselves. Star fish and sea urchins use water vascular system to obtain energy by reacting oxygen with glucose so to give water a carbon dioxide and ATP" (Adenosine triphosphate) (1).


Water vascular system use cilia and ampullae to make things move and “Ionic imbalances allow water to pass through the madreporite and inter into the waver vascular system. Some of the water directed to the coelon and where there is a circulated of the water beating by cilia. Echinordata stretch their muscle that allows water to pass through in to the tube feet and this can cause them to expand to the ground and it can also allow the feet to retract. Echinodermata is divided the different classes namely: Asteroidea, Echinodermata, Holothuroidea, Opiuroroidea and Echinodea” (1).

Star fishes are marine invertebrate species that belong to the class Astreroidea. “These species are closely related to the brittle stars. These species found at the bottom of the ocean or sea and they feed themselves on other organisms found in water, so they use water vascular system to feed themselves. Star fishes species do not have back bone and they use water vascular system which are found on the ventral face of the sea fish’s arm and this mean that this system help them to swim or to move from one place to another” (1).


Star fishes have eyes at “the end of each arms which is able to see in dark and light places which can be useful in sensing movement" (1). Their mouth is found on the undersurface while their anus is found top. Medreporite is found on the aboral surface and it act as a water filter and it supplies water vascular of the star fish with the water to make it move from one place to another” (1). Some of these species have five arms and some have more.


Sea daisies species belong to the class Echinoderms. Its “water vascular system is dotted with the tube feet at the edge of the disk. They also have five ambulacra areas and they nutrition through the membrane from their body because they do not have mouth as well as arms. They also have two circummoral canals and peripheral ring of podia” (2). Sea lilies species belong to the class Crinoidea and they are found in low water at the bottom of the ocean about 6000 meters depth. Their mouth is” situated on top of the surface and surrounded by their feeding arms and they have stem which is used to attach themselves” (3).


Sea urchins belong to the class Echinodea which are found in the ocean. They have “five fold symmetry which helps them to move from one place to another using the tube feet” (4). They do not have eyes and the legs but they use tube feet to move, they depend on the algae for their survival (4). Sae cucumber species belong to the class Holothuroidea and they are found at the bottom of the sea. They depend on “the debris for their survival, so they can get food only when they are at the place where the food flow by with their tentacle when they open their mouth and sift through mouth while eating, and they breathe through their bottom” (5).


The last species are Brittle stars which belong to the class Ophiuroidea. They have five arms which are flexible and they can "redevelop lost of arms " (6) and they use them to run away from their enemy. “The vessels of water vascular system end into tube feet” (6). All Echinodermata have complex nervous system which are found at their skin and they are “sensitive to touch, light, temperature and status of water around them” (4). They can also dwell in brackish water.


References:

1. Wikipedia contributors. Sea star [internet] wikipedia, The Free Encyclopaedia, 2006 May 07, 12:55 UTC [Cited 2006 May17, 12;00]. Available from:
http://en.wikipedia.org/wiki/Sea_star

2. Wikipedia contributors. Sea daisy [Internet] wikipedia, The Free Encyclopaedia, 2006 May 8, 12:13 UTC. [Cited, 2006 May 07, 10:54] Available from:http://en.wikipedia.org/wiki/Sea_daisy


3. Wikipedia contributors. Crinoidea [internet] wikipedia, The Free Encyclopaedia, 2006 May 8, 12:13 UTC. [Cited 2006 May 04, 18:14]. Available from: http://en.wikipedia.org/wiki/Crinoidea

4. Wikipedia contributors. Sea urchin [internet] wikipedia, The Free Encyclopaedia, 2006 May 06, 22:19 UTC. [Cited May 2006, 13 45] Available from:
http://en.wikipedia.org/wiki/Sea

5. Wikipedia contributors. Sea cucumber [internet] wikipedia, The Free Encyclopaedia, 2006 May 10, 12:05 UTC.[Cited May 2006, 11:50] Available from:
http://en.wikipedia.org/wiki/Sea

6. Wikipedia contributors. Brittle star [internet] wikipedia, The Free Encyclopaedia, 2006 May 22, 22:02 UTC.[Cited May 2006, 12:00]. Available from:
http://en.wikipedia.org/wiki/Brittle_star


Lizzy Maluleke
CSIR PTA
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