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23. Echinoderms II Nov 18 2009

23. Echinoderms II Nov 18 2009 - Phylum Echinodermata...

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Unformatted text preview: Phylum Echinodermata Phylum Echinodermata sea stars, urchins, sand dollars, cucumbers, etc. All marine ~6,000 Living Species Internal skeleton Calcarious ossicles Loose or fused - Test 5 Classes Asteroidea - sea stars Ophiuroidea - brittle stars Echinoidea - urchins and sand dollars Holothuroidea - sea cucumbers Crinoidea - sea lilies, feather stars Major body cavity Coelom Enterocoely No excretory organs diffusion Water - Valscular System Water derived from the coelom Dioecious External Fertilization Deuterostomes Enterocoely Radial Cleavage Bilateral Larva Radical Metamorphosis Adults 2º Radial Symmetry Radial Adult – 5 part symmetry Oral surface - mouth Aboral surface - opposite mouth Mutable collagenous tissue Capacity to change mechanical properties in < 1s to a few minutes Under nervous system influence/control Ligaments are normally "locked" (rigid), but can be temporarily "unlocked" (loosened) 1 Class Asteroidea – sea stars Pentamerous (5 part symmetry) Oral surface against substrata Arms = Rays Aboral surface Oral surface Class Ophiuroidea Brittle Stars, Basket Stars ~2000 spp Few large ossicles - articulate 5 equal rays brittle stars - simple basket stars - branched Lack Pedicellariae & Papulae Because covered with ossicles ! tube feet, gut, bursae used for respiration Bursae - ciliated pockets (2 / arm) - open – oral side - pump water - contain gonopores ! brood chambers Water-vascular system Madreporite: absent or present ! oral shield less prominent in brittle stars, more in baskets some species may end blindly Rest similar to sea stars Except Tube feet do not have suckers or ampullae 2 Perivisceral coelom reduced Nervous System: similar to sea-stars - light sensitive skin Reproduction: separate sexes gonads in disk – 10 ! open into bursae Indirect dev ! free swimming - Larva Ophiopluteus Direct dev ! brood in bursae Ophiopluteus Larvae have internal Larvae skeletal ossicles ossicles Class Echinoidea (hedgehog) sea urchins, sand dollars, heart urchins, sea biscuits Covered with spines Lack rays Ossicles fused - test (internal skeleton) Class Echinoidea sea urchins, sand dollars, etc. Covered with spines spines covered with epidermis some with toxins Ossicles fused - test (internal skeleton) 3 covered with spines Spines covered with epidermis Moveable Used for: - locomotion - feeding - burrowing - protection Stalked Pedicellariae: ossicle, muscles Types: Mechanical – tridentate, Ophiocephalous - trifoliate Venomous – globiferous Oral Surface ! contact with substratum - peristomial membrane gills (10) - podia - pedicellaria - spines Aboral surface - periproct - madreporite - anus - gonoducts Tube feet ! pores in test - 2 pores/foot Oral Surface Mouth Tube Feet Gills - 10 Regular echinoids: Oral Surface ! contact with substratum - peristomial membrane gills (10) - podia - pedicellaria - spines 4 Herbivores Special Jaw Aristotle's Lantern Aboral surface - periproct - madreporite - anus - genital pores - sensory tube feet Plus spines Periproct: - 10 ossicles - 5 tube feet – modified for sensory - 5 genital pores - 1 madreporite Spines: muscle control - on tubercles - epidermal covering - venom cavity Stalked Pedicellariae: ossicle, muscles Types: - Mechanical – tridentate, Ophiocephalous, Trifoliate - Venomous – globiferous Tube Feet: through pores (2 each) - reinforced with ossicles - have ampullae Radial Canals: like sea-star - ring canal ! canal to aboral surface Ossicles fused ! Test – internal shell Calcite Mutable collagenous tissue Capacity to change mechanical properties in < 1s to a few minutes Under nervous system influence/control urchin min. 120 years old Grow by increasing size of individual ossicles Grow ossicles Degrow by decreasing individual ossicles by ossicles Ossicles held together by ligaments of collagen Ossicles held Ligaments are normally "locked" (rigid), but can be temporarily "unlocked" (loosened) 5 Mutable collagen in ligaments holding ossicles holding ossicles together together Relaxes to add Relaxes calcification at calcification edges - grow or resorb - degrow or Areas with tube feet - Ambulacral Areas Without tube feet - Interambulacral Without Hard test - all tube feet must go through test Hard Pair of pores for each foot pores for all other connections to outside W-V system - similar to stars Ring canal ! canal to aboral surface (homologous to stone canal) Madreporite Radial canals => ambulacra Ampullae Tube Feet: through pores (2 each) - reinforced with ossicles Tube Feet Pores in test 2 pores per foot Mucus glands Tube Feet - very extensible, strong - connective tissue & muscle Pores in test 2 pores per foot Locomotion Attachment Feeding Respiration Eliminate Waste Sensory Organs Inside the body - main body cavity = Perivisceral Coelom Inside main Perivisceral 6 Digestive system Herbivores - consume macroalgae consume macroalgae Aristotle’s Lantern > 40 skeletal elements + muscles 5 hard teeth MgCO3 Special Jaw: Aristotle's Lantern Esophagus Stomach - wraps around Stomach wraps inside of test inside Siphon- tube parallels tube stomach - ciliated, gut ciliated, bypass for water bypass Long intestine to anus Well developed hemal system Well system Distribute nutrients around body Axial Organ - next to stone canal Axial lots of blood Most tissues and organs with hemal vessels with vessels Nervous system - like sea stars Nervous oral nerve ring, radial nerves very diffuse organization Reproduction 5 gonads - interambulacral 5 pores on genital plates at aboral surface Dioecious Free Spawn direct development or indirect - Pluteus larva with internal skeleton Diadema - mass die off due to disease early 1980's No recovery yet 7 Irregular Urchins 1983 - most abundant urchin on 1983 Caribbean reefs Within a few months - 98% mortality Within Predicted spread of disease by currents Very slow to recover Deviations from the almost perfect radial symmetry of regular urchins Low density - too low for Low too successful fertilization successful inhibited recovery in many areas Heart Urchin Sand Dollars very flat mouth central on oral side Anus move to Anus oral side as well oral Class Holothuroidea sea cucumbers Elongate along the oral-aboral axis aboral axis Mouth and anus widely separated Class Holothuroidea sea cucumbers body wall thick loose ossicles muscular 5 longitudinal muscle bands 8 Buccal tentacles 10 or more modified tube feet deposit or suspension feeding Mutable collagenous tissue capacity to change mechanical properties in < 1s to a few minutes under nervous system control Ability to maintain a variety of postures with no muscular effort. Holothuroids - entire body wall contains mutable collagenous tissue. Digestive system Buccal Capsule: fused ossicles – support ossicles - ring canal - nerve ring Hydrostatic skeleton important but postures and spines held with mutable collagen Muscles can contract and draw whole apparatus and into anterior portion of body into Intestines very long and very coiled in body coiled Respiratory trees in hind gut Tubes of cuvier: blind tubes of respiratory tree Respiratory Trees hind gut outgrowths ventilate water in and out 9 Tubes of Cuvier part of respiratory tree sticky some toxic - saponins ejected when disturbed Evisceration eject digestive system out mouth when disturbed seasonal resorption of gut very good at regeneration Deposit feeds, particulate matter ciliated tentacles collect particles on mucus put tentacles in mouth one at a time to remove food Water-vase-system: ring canal ring => tentacles => => radial canals => tube feet not all have tube feet Polian vesicles Stone canal => madreporite – but opens into the coelom Stone madreporite Reproduction dioecious single gonad indirect development Aricularia Larva Doliolarian larva Direct development Some brood Some Can brood in coelom coelom 10 10 Class Crinoidea sea lilies - stalked feather stars - not stalked ~5000 extinct species ~550 living feather stars ~80 spp sea lilies (stalked) most deep water Both stalked and Both feather stars use feather Cirri to hold onto surface Oral surface up mouth and anus on oral surface Suspension feed – tube feet Mouth Anus Pinnule Body – Body Calyx – fused ossicles Tegmen – soft oral surface Branching rays with jointed Pinnules Stalk, Cirri Suspension feeders 5 ambulacral grooves radiate from mouth ambulacral To ray branches and pinnules To pinnules Grooves border by Lappets (closable) Each lappet associated with 3 tube feet (mucus, cilia) Each tube Oral surface of Oral Calyx Calyx 11 11 Reduced internal space Coelomic space reduced - broken up by connective tissue space Perivisceral coelom extends into each ray, pinnules Perivisceral pinnules Water-Vascular-System: similar to others but No Ampullae but Ampullae Several stone canals – open into coelom Several open coelom Oral surface of calyx has many pores Separate sexes: Gonads in pinnules (or rays) free spawn or brood free direct or indirect develpoment develpoment doloarian larva doloarian larva Regeneration good – pinnules good bad - calyx bad Echinoderms important for studies of: Ecology Keystone predators, major herbivores, Keystone important coral reef predators important Development Urchin and sand dollar - model systems Urchin Immune systems Regeneration Life History Life larval biology, importance and consequences of different consequences modes of reproduction 12 12 ...
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