Skeleton/SupportThey have an internal skeleton, also know as the endoskeleton. The skeletons is a rigid shell made of flat and fused calcium carbonate bones called calcareous ossicles. It is divided into 10 sections, going from mouth to anus. 5 of the sections with holes on the tube feet are called ambulacral plates, and the other 5 without one are known as the interambulacral plates.
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MovementEchinoderms have tube feet with suction pads.
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Gas Exchange/ RespirationEchinoderms have a poorly developed respiratory system. They use some of the bumps or spines on its surface to take in oxygen. Simple diffusion is used through the tube feet and simple gills.
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Habitat/LifestyleEchinoderms are exclusively marine. They can be fund in various habitats around the world/oceans. They have diversified into a number of different lifestyles. Some are predators or filter feeders.
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ExcretionWastes composed of mostly nitrogen, usually in the form of ammonia, don't have a special organ dedicated to excretion, and so simply diffuse out through the tube feet and skin gills.
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Sensory/Nervous SystemThey have a network of nerve plexus, which are made up of intersecting nerves under the skin and throughout the appendages.
Their eyespots at then end of each arm allow them to detect light and darkness. Some tube feet are sensitive to chemicals and allow them to find the source of a smell, such as their food. Star fish have a central nerve ring which lines the esophagus and send radial nerves into each of the arms. These nerves often run parallel to the water vascular system. |
Transport/CirculationEchinoderms have two different circulatory systems:
2. Transport system, which circulates body fluids throughout the tissues |
Digestion
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Life History/ReproductionEchinoderms larva have radial symmetry while their adult form has radial symmetry. The larva have a 3 part coelom and have cilia which helps them swim. When fully developed, they settle on the seabed to undergo metamorphosis.
Sexual: They exhibit external fertilization. Asexual: Parts of their body can break off and create more. |