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Echinoderms_and_Invertebrate_Chordates_29_.ppt.pptx
- 1. 1 Phylum Echinodermata “The spinyskinned animals”
- 2. 2 Echinoderm Facts • Hard,spiny, bumpy endoskeleton made of calcium carbonate covered w/a thin epidermis. • As adults, echinoderms have radial symmetry with branching arms called rays. • As larva, echinoderms have bilateral symmetry. • Echinoderms have no head or brain, but they do have a central nerve ring that surrounds the mouth. • Water vascular system (WVS) is a hydraulic system that operates under water pressure used for movement.
- 3. 3 Echinoderm facts • Thewater vascular system’s opening is called a madreporite. It opens into a ring canal. The ring canal then goes out to the arms in radial canals. The radial canals then feed water to the tube feet. • Each arm contains two rows of tube feet
- 4. 4 Echinoderm facts • Tubefeet are used in movement, gas exchange and excretion; nitrogen waste excreted as ammonia exits the anus. • At the top of each tube foot is the ampulla which acts like a bulb on a medicine dropper. • Echinoderms are considered to carnivores, herbivores and detritus feeders. • Simple nervous system for most echinoderms – Starfish have up to 200 light sensitive cells clustered in eyespots of each arm. No actual eyes. • Pedicellariae are pincher-like appendages used for protection and for cleaning the surface of the body. • For balance & hearing, statocysts or tiny stones pass over hairs to tell the starfish up from down and sense motion or sound by vibrations in the water.
- 5. 5 Echinoderm Reproduction • Echinodermscan reproduce sexually or asexually. • Reproduction – echinoderms are either male or female. Sperm and eggs produced in the testes or ovaries is released into the water to become fertilized. This is sexual reproduction. • Reproduction – ask a Fisherman and he will tell you that tearing starfish into chunks is a great way to increase their population. Each chunk will undergo regeneration (asexual reproduction) and form new starfish. So, ripping them up is not a great way to reduce predation on shellfish, which bring in a pretty-penny.
- 6. 6 Echinoderms • The spinyskinned animals include these Classes: 1.Class Asteroidea - starfish (sea stars) 2.Class Crinoidea - the crinoids or “feather stars” 3.Class Ophiuroidea - brittle stars, basket star 4.Class Echinodermata - sea urchin, sand dollar 5.Class Holothuroidea - sea cucumbers 6.Class Concentricycloidea – sea daises
- 7. 7 Class Asteroidea • Includes¼ of the echinoderms • Sea stars or starfish • Sea stars typically have 5 arms but can have up to 40. • The mouth is located on the oral or bottom side. • The anus is located on the aboral or top side.
- 8. 8 Starfish arm • Eacharm or ray contains a digestive glands, a radial canal and gonads. • Each arm also contains two rows of tube feet. • Arm will regenerate if torn off = Asexual Reproduction. • Starfish are carnivores that eat clams, mussels, and other bivalves.
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- 10. 10 Endoskeleton Madreporite Tube feet Pedicellariae Anus Stomach Digestive gland Eyespots Ray Nerve ring Mouth Reproductive organ Endoskeletal plates Radial nerveAmpullae Radial canal Ring canal Sea stars
- 11. 11 Class Crinoidea • Sealilies & feather stars • Filter feeders • some are sessile • some are motile • Their bodies are often found in limestone deposits
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- 14. 14 Class Ophiuroidea • Brittlestars & Basket Stars • These are perhaps the fastest of the echinoderms. Do not use tube feet for movement. • Most of them are filter feeders or detritus eaters • Flexible arms, and may be offered as food to get away from predators
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- 17. 17 Class Echinoidea • SeaUrchins & sand dollars • Lack arms or rays • eat algae or are detritus eaters • usually have spines • Gonads prized for sushi • Endoskeleton called a test.
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- 20. 20 Class Holothuroidea • Seacucumbers • Detritus eaters – the vacuum cleaners of the sea • do not have skeletal parts • will eviscerate if they are scared, meaning offer up internal organs as food to distract predator
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- 22. 22 Class Concentricycloidea • Seadaises • Discovered off the coast of New Zealand. • Flattened disc bodies less that 1 cm in diameter. • Three known species to date.
- 23. 23 Phylum Chordata • Threesubphyla –Phylum Urochordata - tunicates –Phylum Cephalochordata - lancelets –Phylum Vertebrata - vertebrates
- 24. 24 Invertebrate Chordates • Thisgroup belongs to the Phylum Chordata because they contain a stiff but flexible rod called a notochord. • Characteristics –dorsal nerve chord - hollow tube –pharyngeal pouches - out pockets in pharynx –postanal tail - used for propulsion
- 25. 25 Subphylum Cephalochordata • Lancelets-retainall characteristics throughout its life. • Like to burrow in shallow water sand. • Usually about 5 cm long. • Filter feeders http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9a/Lancelets/Lab_9a- 03a.jpg
- 26. 26 Subphylum Urochordata • Tunicates- AKA “Sea squirts” because their bodies are covered with a tough covering like tunic. • Filter feeds as adults w/incurrent siphons • External fertilization - hermaphrodites that release sperm through excurrent siphons.
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