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Echinoderms: The Spiny Animals! Bethany Anding Characteristics • There are about 6,000 species of Echinoderms. • Sea Stars, Sea Cucumbers, Sea Urchins, and Sand Dollars • Echinoderms have radial symmetry, an endoskeleton, a water vascular system and a coelomic circulation and respiration system • Echinoderms do not have a brain or complex organs Spiny Skin • Radial symmetry – Most echinoderms have a central point from which limbs grow out of • Endoskeleton – Ossicles fuse to form joints, muscle attachment sites, and shell like protection – Most ossicles grow upward through skin • Water-vascular system – Interconnected canals and tube feet that form a water-filled system • Tube feet are how most echinoderms move across the sea floor • Coelomic circulation and respiration system • – Body cavity is the circulatory system – Skin Gills clean out the air for the echinoderms, taking in the air particles needed and getting rid of the ones not needed http://videos.howstuffworks.com/hsw/16841-animals-without-backbonesechinoderms-video.htm Sea Stars • Sea Stars are also known as star fish • Classification – Class-Asteroidea • There are about 2,000 species of sea stars – Orange Marble Starfish – Fromia Ghardagana (Ghardaga Brittle Star) – Gomophia Egyptiaca (Egyptian Sea star) • Known to be in marine waters – It can be on rocky, sandy and muddy sea floors • Sea stars are found in shallow waters Sea Stars cont.. • Uses – Marine aquariums • Carnivores – – – – Clams Oysters Coral Fish • Tube feet – Attach to shell and pries open • Stomach – Sea stars push their stomach through their mouth to digest prey – The stomach releases digestive enzymes that puree the flesh of their victim so the sea star can absorb it • Hard-skinned animals – Not fish Reproduction Sexual 1. Huge amounts of eggs and sperm are released 2. Fertilization is external 3. The Embryos are very tiny • Transparent and bilateral symmetry 4. Ocean currents carry the embryos for about two months • They form part of zooplankton 5. Grow by eating phytoplankton 6. Grow out of zooplankton and develop radial symmetry Asexual 1. An arm is split off of a sea star 2. This limb grows into an independent sea star 3. Original sea star re-grows limb Sand Dollar ¤ Classification ¤ ¤ There are about 1,000 species ¤ ¤ ¤ ¤ ¤ ¤ Class-Echinoidea Arrow head Flat Round Sea Biscuits Pancake Sea Gopher Marine Waters ¤ ¤ ¤ ¤ Be buried under a layer of sand on the sea floor Found in intertidal zone (between high and low tide) Also found in subtidal zone (below low tide) Usually found in shallow waters Sand Dollars cont… • Usually • 7.5 cm in diameter • 1 cm thick • 5 to 10 cm wide • Usually purple-blue – Can fade due to location • • Has no arms or legs Move with the tiny spines that surround their body – The fine layer on the top of the sand dollar • There are also tube feet on the top • Slow moving grazers – Mouth is sitting on the ground – They eat disintegrating organic materials within their sand beds • Tiny particles of food that float in the water • Eaten by – Sea stars – Snails • Sand dollars only have a spine when they are alive • Their dead shell is called a test – Scientist have traced sand dollars tests’ to the Ordovican period • They cannot live out of the water • Use tube feet to breathe – Tube feet take in oxygen from water, the oxygen passes through their tiny layer of skin • Uses – Sand dollar eggs have been used to better understand cell division and things related to uncontrolled cell growth • Cancer Reproduction • Sexual – Gonads swell in May • This lasts until July or August – Dendraster discharges eggs that are ripe through the gonopores – Fertilization is external • Male protrudes his genital papilla from body wall so the sperm can travel farther to get to the egg externally – In 2-4 days four armed larvae are developed and become part of the zooplankton • When first hatched sand dollars are bilaterally symmetrical • They also have several arms to feed – Eggs can travel away from parent bed while in the ocean currents • Larvae develop – Chemical signals are produced – The sand dollar settles in a sand bed and undergoes metamorphosis to grow into an adult sand dollar form Sea Urchins • Sea Urchins are often known as the “hedgehog of the sea” • Classification – Class Echiniodea • There are about 6,000 living species – – – – – – The biggest is the red sea urchin (18cm) Pencil sea urchin English channel sea urchins Whole sputnik sea urchin Purple sea urchin Jewel case sea urchin • Marine Waters – Found from shallow waters to waters of great depth – Tide-pools – Also found on the oceans bottom Sea Urchins cont… • Uses – – • Color – – • Can range from .5cm-38cm Diet – • Most common is purple-light pink Also brown, black, green, white, or red Size – • In the West Indies people eat the sea eggs (ovaries) of the sea urchin raw or fried Sea Urchins also evoke the flavor of caviar Kelp, seaweed, algae, dead fish, sponges, mussels, barnacles, bits of plants and animals, and decaying matter Mouth – The sea urchin’s mouth is claw like (Aristotle’s lantern) • 5 tooth-like plates that point towards each other – – They help trap small particles like algae • • • Continue to grow throughout lifespan Pull, tear, rip algae off rocks The mouth is located in the middle of the back side The anus and genital spores are on the top side of the sea urchin Sea Urchins cont… • Predators – Some birds, humans, fish, sea otters, sunflower stars, snails, and crabs • Movement – Sea Urchins have no arms or legs, but have long spines that replace them – These spines are used to move, catch prey, and as a defense mechanism – There are also five paired rows of tube feet with suckers • These help them move and catch prey also • They also help the urchin hold on to the sea floor – Spines have toxin sacs on that are very fragile • When one steps on a spine the sac erupts and the venom is injected into the victim • Tests – The sea urchins’ tests have traced the animal back to 500 million years ago Reproduction • Females release several million jelly-coated eggs at a time – The eggs or sperm are released through five gonopores • • Fertilization is external Development – Larvae (pluteus) • Have bilateral symmetry – Larvae swim in sea alone with the zooplankton • • • Several months of development for a juvenile sea urchin to form The bottom and top side are formed and they settle on the sea floor This lasts about 2 to 5 years Sea Cucumbers • • • Also known as Holothurians (coral reef) Class-Holothurioidea It is known that they have been around for 400 million years – • There are about 1,250 described species – – – – • Silurian Period White-Spotted Sea Cucumber The Edible Sea Cucumber The Light-Spotted Sea Cucumber Alabaster Worm Cucumber Mostly marine waters – – Fine sand and mud Shallow waters • – Deep waters • – • Exposed to the surface Some on algae Others bury on the sea floor Life span – – 5 to 10 years Some can live very long as plankton Sea Cucumbers cont… • Omnivore – • Tiny marine animals, dead and decaying organic matter Color – Most are black, brown, or olive • • Size – Can range from 2 to 200cm long and 1 to 20cm thick • • There has been a sea cucumber measuring 5 meters! Soft-bodied – – Spherical to long and worm like Bumps/warts • – • Can be brightly colored or patterned Cucumber or sausage leathery Uses – Asia • • – Tropical islands • – Soup, stews, stir-fries Many dishes Threads for protection against coral reef Natives of Alaska • Canned sea cucumbers Sea Cucumbers cont… • Predators – • Fish and many other marine animals Protection – – Cucumbers eject long sticky threads through the anus to wrap up their enemy Internal organs pushed out that releases a toxin that is deadly to fish • – Organs grow back in about six weeks Movement • • Sea cucumbers have five rows of tube feet that provide movement Some sea cucumbers can swim – • Podia – Feet • 8-30 rows that surround mouth – • • • Scattered These help capture food and help with burrowing Non-radial appearing Calcareous ring that surrounds throat – • • Deep sea Attachment point for controlling muscles Circlet or oral tenticles Ossicles are very small – wheels Reproduction • Sexual has two stages – Gametogenesis and spawning • Gametogenesis • Spawning – – – Release of gametes in water broadcasts and brooding » Let free » Males catch their eggs with tentacles and put them on their lower part of their body – – – The male lifts anterior end and releases gametes Females follow The fertilization is external – – Larva float in ocean until it finds an appropriate place Larvae transform into juvenile sea cucumbers • • Formation of sperm and ova Many to be successful Asexual – Transverse fission (3 ways) • Attach anterior to posterior tube feet – • Divide into 3 parts – • Attaches both ends and bloats gut » Twists and body wall ruptures Divides into halves – – Thins the middle of the body » Middle breaks Attaches both ends and bloats gut » Twists and body wall ruptures Regenerate either the anterior or posterior end, which ever one was lost Question 1 ☺ What is the most commonly known echinoderm? a. b. c. d. The brittle star The sand dollar The sea urchin The sea star Question 2 ☻ Which echinoderm does not have asexual reproduction? a. b. c. d. Sea star Sea cucumber Sand dollar None of these Question 3 ♂ What are some common uses of sea cucumbers? a. b. c. d. Marine aquariums Many Asian Foods To better understand cell division All of the above Question 4 • T or F – Sea Urchins are known as the hedgehog of the sea. Question 5 ۞ There are about ______ species of echinoderms. a. b. c. d. 4,500 6,000 8,000 10,000 Sources • http://www.cyhaus.com/marine/Echinoder m.htm • http://www.oceaninn.com/guides/echino.ht m • http://www.enchantedlearning.com/subject s/invertebrates/echinoderm/Seastarprintou t.shtml • http://www.wetwebmedia.com/seastars.ht m