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35 Cards in this Set
- Front
- Back
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Echinodermata
General |
- No heads (cephalization)
- No eyes - No sense direction - Radial symmetry - Oral and aboral surfaces |
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Echinodermata
Characteristics |
- 6500 ssp.
- 13000 fossil ssp - Only marine |
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Echinodermata
Classification |
Class Stelleroidea
- Subclass Asteroidea (Sea star) - Subclass Ophiuroidea brittle star) Class Echinoidea (Sea urchin, sand dollar) Class Holothuroidea (sea cucumbers) Class Crinoidea (Sea lilies) |
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Echinodermata
Apomorphy |
- Pentamerous radial symmetry
- Water vascular system - Mutable connective tissue |
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Echinodermata
Body covering and skeleton |
- Epidermis, dermis (derived from mesoderm)
- Dermis with ossicles - Muscle layers beneath dermis - Tubercles and spines - Pedicellaria (pincer like structures, respond to stimuli) - Papulae (gas xchange) |
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Echinodermata
Pedicellaria |
- For removal of debris, settling larvae
- Produce toxin - Hold materials for camouflage |
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Echinodermata
Water Vascular System |
- Internal canals and closed extensions.
- Derived from coelom, outpouching from digestive tract into 3 chambers - Madreporite - Stone canal leads to ring canal with many radial canals. - Extensions to outside through podia (tube feet) |
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Echinodermata
Tube Feet |
- Composed of muscle
- Thin - Gas exchange surfaces - Adhesive/glue (dual gland system) - Extend to outside via ambulacral grooves |
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Echinodermata
Mutable connective tissue |
- Change rigidity rapidly from hard to soft
- Used as defense, autotomy (arm of sea star breaks off) and evisceration (burp out internal organs of sea cucumber). - Hardening for spine locking and feeding. |
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Echinodermata
Hemal System Morphology |
- Separate set of flid filled channels
- Ring and radials - axial organ - Possibly used to transport fluids from the coelomic fluid to the gonads |
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Echinodermata
Hemal system Function |
- Nutrient transport
(Experiment done with radioactively labeled food) - Axial organ with excretory function - Produce coelomocytes (immune system) |
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Echinodermata
Nervous System |
- Decentralized, diffuse
- No brain - Three nerve networks and a nerve net - Ectoneural - sensory stimuli - Hyponeural - motor function |
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Echinodermata
Digestive System |
- Predators, grazers, filter/suspension feeders
- Full functioning digestive tract |
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Echinodermata
Reproduction and Development |
- Asexual (limited)
- Sexual, dioecious - External fertilization - Indirect via planktonic larvae - Direct via brooding of young. |
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Echinodermata
Origin of penta radial symmetry |
- Developmental regulatory genes, specify anterior-posterior parts.
- Lowe and Wray used 'engrailed' gene. - Found 'engrailed' gene in each arm (normally expressed anterior to posterior in bilateral animals) - Like one animal grew 5 bodies... |
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Class Crinoidea
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- Feather stars, sea lilies
- Most ancient - 700 ssp. |
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Class Crinoidea
Morphology |
- Body on stalk or stalkless w/ claws
- Mouth and anus upwards (U shape) - Crown is pentamerous - Stalk is retained in sea lilies - Stalk is lost post larval development of feather stars |
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Class Crinoidea
Stalks.. |
- Protective calcareous plates on outter surface
- stalk looks jointed - Cirri on stalk - Used for grasping substrate |
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Class Stelleroidea
Characteristics |
- All armed echinoderms
- 2 subclasses - Arms are 5 or 5x from central disc |
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Subclass Asteroidea
Characteristics |
- 1800 ssp.
- Sea Star - Arms not distinct from central disc - no rapid movement - Predators |
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Subclass Asteroidea
Specifics |
- Gonads and digestive tract extend into arms
- 2 stomachs (pyloric and cardiac) - Can evert stomach to feed - pedicellariae - Distinct ambulacral grooves |
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Subclass Ophiuroidea
Characteristics |
- 2100 ssp.
- Marine - Brittle stars, basket stars - All are motile, fast/rapid |
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Ophiuroidea
Specifics |
- Arms sharply set from central disc (may be branched)
- Arms solid, appear jointed - Podia have no role in locomotion - Surfaces w/ plates or sheilds - Vertebra (internal ossicles, each set of sheilds) - podia are tentacle like - no papulae, no pedicellariae and no anus. |
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Class Echinoidea
Characteristics |
- Sea urchins, sand dollars
- 1,000 ssp. - Oval/spherical shape w/ no arms (spines instead) - Flattened body on oral/aboral surface - Rigid tests - two groups: Regular and Irregular - 7000 shared genes w/ humans |
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Echinoidea
Regular |
- Radial
- Sea urchins - Epifaunal, live and move on sea floor |
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Echinoidea
Irregular |
- Bilateral
- Heart urchines, sand dollars - Infaunal, burrowing |
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Echinoidea
Locomotion |
- Spines
- Tube feet * Also used for "non locomotion" to brace themselves in place |
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Echinoidea
Aristotles Lantern |
- Specilized scraping apparatus
- 5 calcareous plates - Pointed end toward mouth - only in sea urchins and sand dollars |
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Echinoidea
Feeding |
- Urchins: graze and scrape substrate
- Heart urchins: burrow, slective deposit feeders. - Sand dollars: just beneath surface of sand, pick up particles w/ podia |
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Echinoidea
Spines |
-Long thin and sharp or thick and round
- Toxins associated w/ spines |
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Class Holothuroidea
Characteristics |
- Sea cucumbers
- 1200 ssp. - Suspension and deposit feeders - Abyssal habitats (ocean floor below 2000 meters) |
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Holothuroidea
Morphology |
- Stretched sea urchin, elongate tube
- No arms - Modified podia around mouth, tentacles (part of WVS) - Ossicles reduced |
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Holothuroidea
Gas Xchange |
-Respiratory trees: system of tubules, highly branched, filled with water
- No trees in pelagic or benthic species, gas xchange through tube feet. |
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Holothuroidea
Evisceration |
loss of internal structures, via mutable tissue. Can regenerate.
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Echinodermata
Ecology |
- Economic and ecological importance
- Decimate sea weed/grass. Distroy fish habitat. Starfish destroy coral reefs - Major predator of molluscs - Otters are keystone species. W/o otters, urchins overpopulate and destory kelp forests. |
