By Hillary Goins Zoology 8 th Period

1. Echinoderms By Hillary Goins Zoology 8th Period

2. Basic Info on Echinoderms • Approximately 6,000 species • Found in all oceans of the world • Move by suction cup appendages and have skin covered with tiny, jaw-like pincers; their tube feet allow them to break open the shells of bivalves • All have bumpy endoskeletons covered by a thin epidermis • Endoskeleton is primarily made up of calcium carbonate • Echinoderms use a jaw-like pedicellariae for protection and for cleaning the surface of theirbody • They have radial symmetry which enables echinoderms to sense from all directions • Contains a water vascular system that allows them to move, exchange gases, capture food, and excrete wastes

3. CONT’ Basic Info on Echinoderms • Gases are exchanged and wastes are eliminated by diffusion through the tube feet • Simple nervous system • All echinoderms have a mouth, stomach, and intestines • Do not have a head or brain, but they do have a central nerve ring that surrounds the mouth; They have a nerve ring that extends down the rays • Have cells to detect light and touch, but they so not have sensory organs except for Sea stars • Have bilaterally symmetrical larvae

4. Class Asteroidea • Common name: Sea Star • 1500 species • Most have 5 rays, but some may contain up to 40 or more • Only echinoderm that contains sensory organs • Carnivorous and also eat worms or mollusks such as clams • Contain tapering arms called rays • Rays are tapered and extended from the central disk

5. Class Ophiuroidea • Common name: Brittle Stars • 2,000 species • Extremely fragile • The rays of a brittle star will break if you pick them up, therefore this is an adaptation to protecting itself from predators • Rays will regenerate in weeks • Do not use their tube feet to move, instead they propel in a slithering motion of their rays. • Feed on dead decaying matter • They use their tube feet to get food particles into their mouth

6. Class Echinoidea Sea urchins Sand dollars Approximately 950 species of Echinoids • Look like pincushions • Disk shaped body covered with spines • Don’t have rays • They have long slender tube feet • Their spines protect them from predators • Contains poisonous fluid that are located at the tips of the spines • The spines help allow the Sea urchins to move and burrow into the sand/ground • Globe or disk-shaped body with spines • Don’t have rays • Skeletons have a flower shape with 5 petals • Living sand dollars are covered with hair-like spines that are lost when the organism dies • Their tube feet are modified into gills • Also, their tube feet on the bottom surface of their body helps to bring organic particles found in the sand into its mouth

7. Class Holothuroidea • Known as Sea cucumbers because of their vegetable cucumber shape • Have a leathery covering that allows it to be very flexible • Move by using tentacles and tube feet • Reproduce by releasing eggs and sperm into water and then fertilization takes place • For protection, Sea cucumbers create a sticky mass of tubes through the anus, or they may rupture, releasing internal organs. This confuses the predator so the Sea cucumber can make its escape. • Feed on dead decaying matter • About 1500 species

8. Class Crinoidea • Consists of Sea lilies and Feather stars • Approximately 600 species • Sea lilies are sessile as adults and Feather stars are only sessile in their larval form • Capture food particles with their tube feet and move it to their mouth • Feather stars use feathery arms to move place to place Feather Star