Echinodermata

__ Echinodermata __ - Form a defined and highly derived clad of metazoans - Among the most distinctive of all animal phyla -Echinodermata - “spiny skin” __ Sea Stars __ - Genus- species- Asterias forbesii - have 5 arms connected to a small round body - Sea stars detect light with five purple eyespots at the end of each arm. Madreporite - sucks water into the starfish that Creates suction at the ends of hundreds of tube feet

__ Reproduction __ - Asexual and sexual - Sea stars breed in the spring, producing as many as 2,500,000 eggs. - Females will feel plump and spongy when their arms are filled with eggs - When a Sea stars' arm is cut off it can generate a new body

__ Body Structure __ - radial symmetry - Most have five arms connected to central disc - Have eyespots on the tips of their arms o eyespots detect light and dark but cannot see details - Do not have a nervous system, have a nerve net o A net nerve means their nerves are spread around their whole body

__ Predators __ - bottom dwelling fish - crabs - Sea Otters - sea gulls and other birds when low tides leave the sea stars exposed - humans who collect them (overall not very many)

__ Nutrition __ - Use suction cups to pry off shellfish - When the prey is opened, the sea star pushes its stomach out of its body and into the bivalve, secreting enzymes that digest the prey's soft body tissues - Sea stars feed often and their size depends with how much they consume not their age - Ingest barnacles, chitons, snails, urchins, limpets, sponges and sea anemones - When eating, the sea star may turn its stomach inside out to reach into the shell of its prey.

__ Circulatory system __ - Use seawater and a complex vascular system to keep things moving - have a tube feet o really small (tiny) tentacles that aid in movement o Located on the underside of the sea stars body - Sea stars are invertebrates so they don’t have a backbone, but they do have a skeleton beneath their skin

__ Gas exchange systems __ - Do not use lungs or gills - Obtain oxygen by diffusion across the surface in their body

__ Excretory System __ - Use diffusion to rid their bodies of nitrogenous waste - mainly ammonia gas.

__ Ecological Niche __ - Rocky shores - tide pools - dock pilings - Ocean floor

__ Role in the environment __ - controls the shellfish population by eating them __ Challenges __ - Shell fish population degrease - Water pollution

__ Evolutionary Advantages __ - Spines that protect them from predators - Pinchers keep algae and other organisms from attaching to it - use their pinchers to snap at intruders -Stomach allows it to feed on larger prey - They can also use their pinchers to clean the sand off their bodies - When they lose an arm, it can grow back - Has a chemical defense that taste bad to predators

__ Life Processes __ - Gastrula o the fertilized egg of the sea star o They are small plankton that float in the ocean and feed on diatoms

- Bipinnaria o Develop arms to help in feeding

- Brachiolaria
o Suckers grow to help them attach to larger surfaces

- Juvenile o About 1mm wide o Take on the shape of a sea star with permanent arms

- Adult o Mature o Reproduce o Can live up to 20 years because they don’t have many predators o Have a larva life cycle

[] : [|Sea Star Life Cycle | eHow.com] []

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Assignment #1
1. The sea star lives in shallow ocean waters and cling to things like rocks and dock pilings. 2. The sea star is ectothermic, so it needs the shallow water for the sake of the heat provided by sunlight. They are found in many warm, tropical places. 3. The sea stars live where there are shellfish to eat. They don’t really need much else 4. The shallow water is warmer than deep water, so more life can flourish there. The shallow water also means lots of large predators can’t come and eat them. More coral and seaweed will grow, providing homes and nutrition for the organisms.