I.Keystone Species

I.Echinodermata A.Echinoidea (Sea urchins, Sand dollars) Approximately 1000 speciesApproximately 1000 species Includes heart urchins, sea biscuitsIncludes heart urchins, sea biscuits Round, rigid test with movable spines and pedicellariaeRound, rigid test with movable spines and pedicellariae Spines and tube feet used for locomotionSpines and tube feet used for locomotion Tube feet in shallow ambulacral grooves along outside of testTube feet in shallow ambulacral grooves along outside of test Complete digestive systemComplete digestive system Mouth on bottom, anus on topMouth on bottom, anus on top HerbivoresHerbivores Feed on seaweeds and seagrasses (especially drifting) plus attached encrusting organismsFeed on seaweeds and seagrasses (especially drifting) plus attached encrusting organisms Mouth includes Aristotle’s lanternMouth includes Aristotle’s lantern

I.Echinodermata B.Holothuroidea (Sea cucumbers) Lack spinesLack spines Five rows of tube feet run from mouth to anusFive rows of tube feet run from mouth to anus Endoskeleton reduced to small calcareous spicules in skinEndoskeleton reduced to small calcareous spicules in skin Complete digestive systemComplete digestive system Respiration through respiratory treesRespiration through respiratory trees Deposit and suspension feedersDeposit and suspension feeders Most tube feet used for locomotionMost tube feet used for locomotion Tube feet around mouth modified as branched tentacles that pick up food from substrate or filter particles from waterTube feet around mouth modified as branched tentacles that pick up food from substrate or filter particles from water “Earthworms of the sea”“Earthworms of the sea” Deposit feeders have long, coiled intestines (why?)Deposit feeders have long, coiled intestines (why?) Evisceration as defense mechanismEvisceration as defense mechanism Can eject toxic filaments or viscera (internal organs) through anus to deter predatorsCan eject toxic filaments or viscera (internal organs) through anus to deter predators

Enypniastes eximia

I.Echinodermata C.Crinoidea (Feather stars, Sea lilies) Suspension feedersSuspension feeders Mouth oriented upwardMouth oriented upward Capture particles with tube feet/mucusCapture particles with tube feet/mucus Ciliated ambulacral grooves transport food to mouthCiliated ambulacral grooves transport food to mouth Cling to substrate with cirriCling to substrate with cirri Capable of swimming Video ClipCapable of swimming Video ClipVideo ClipVideo Clip Feather stars – UnstalkedFeather stars – Unstalked Cosmopolitan, but especially abundant in warm waterCosmopolitan, but especially abundant in warm water Capable of swimmingCapable of swimming Sea lilies – StalkedSea lilies – Stalked Uncommon, restricted to deep waterUncommon, restricted to deep water

II.Lophophorates Three phyla – all animals possess lophophoreThree phyla – all animals possess lophophore Ciliated hollow tentacles arranged in a horseshoeCiliated hollow tentacles arranged in a horseshoe Suspension feedersSuspension feeders Bilateral symmetry, coelom (body cavity), U-shaped gutBilateral symmetry, coelom (body cavity), U-shaped gut A.Bryozoa/Ectoprocta – Bryozoans Colonies consist of interconnected individual zooidsColonies consist of interconnected individual zooids Encrusting and lacy forms (CaCO 3 tests)Encrusting and lacy forms (CaCO 3 tests) Retractable lophophoreRetractable lophophore B.Phoronida – Phoronids, Horseshoe Worms Worm-shapedWorm-shaped Agglutinated sediment tubes attached to hard substrate in shallow waterAgglutinated sediment tubes attached to hard substrate in shallow water C.Brachiopoda – Lamp Shells Abundant in fossil recordAbundant in fossil record Superficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusksSuperficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusks Many attached to substrate with pedicle (short stalk)Many attached to substrate with pedicle (short stalk)

Bryozoa

II.Lophophorates Three phyla – all animals possess lophophoreThree phyla – all animals possess lophophore Ciliated hollow tentacles arranged in a horseshoeCiliated hollow tentacles arranged in a horseshoe Suspension feedersSuspension feeders Bilateral symmetry, coelom (body cavity), U-shaped gutBilateral symmetry, coelom (body cavity), U-shaped gut A.Bryozoa/Ectoprocta – Bryozoans Colonies consist of interconnected individual zooidsColonies consist of interconnected individual zooids Encrusting and lacy forms (CaCO 3 tests)Encrusting and lacy forms (CaCO 3 tests) Retractable lophophoreRetractable lophophore B.Phoronida – Phoronids, Horseshoe Worms Worm-shapedWorm-shaped Agglutinated sediment tubes attached to hard substrate in shallow waterAgglutinated sediment tubes attached to hard substrate in shallow water C.Brachiopoda – Lamp Shells Abundant in fossil recordAbundant in fossil record Superficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusksSuperficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusks Many attached to substrate with pedicle (short stalk)Many attached to substrate with pedicle (short stalk)

II.Lophophorates Three phyla – all animals possess lophophoreThree phyla – all animals possess lophophore Ciliated hollow tentacles arranged in a horseshoeCiliated hollow tentacles arranged in a horseshoe Suspension feedersSuspension feeders Bilateral symmetry, coelom (body cavity), U-shaped gutBilateral symmetry, coelom (body cavity), U-shaped gut A.Bryozoa/Ectoprocta – Bryozoans Colonies consist of interconnected individual zooidsColonies consist of interconnected individual zooids Encrusting and lacy forms (CaCO 3 tests)Encrusting and lacy forms (CaCO 3 tests) Retractable lophophoreRetractable lophophore B.Phoronida – Phoronids, Horseshoe Worms Worm-shapedWorm-shaped Agglutinated sediment tubes attached to hard substrate in shallow waterAgglutinated sediment tubes attached to hard substrate in shallow water C.Brachiopoda – Lamp Shells Abundant in fossil recordAbundant in fossil record Superficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusksSuperficially resemble clams, but shells are dorsal-ventral, not left-right as in mollusks Many attached to substrate with pedicle (short stalk)Many attached to substrate with pedicle (short stalk)

III.Chaetognatha (Arrow Worms) Important components of the planktonImportant components of the plankton Voracious carnivoresVoracious carnivores Sit and wait predatorsSit and wait predators Eat zooplankton (small crustaceans, larvae, eggs)Eat zooplankton (small crustaceans, larvae, eggs) Fig 7.41

IV.Enteropneusta (Acorn Worms) HemichordatesHemichordates Possible evolutionary transition between invertebrates and chordatesPossible evolutionary transition between invertebrates and chordates Share some but not all characteristics with chordatesShare some but not all characteristics with chordates Deposit feedersDeposit feeders Many construct U-shaped burrows and process large quantities of sedimentMany construct U-shaped burrows and process large quantities of sediment Proboscis secretes mucus used to collect organic materialProboscis secretes mucus used to collect organic material

V.Chordata CharacteristicsCharacteristics 1)Dorsal hollow nerve cord 2)Pharyngeal gill slits 3)Notochord 4)Postanal tail Three subphylaThree subphyla Urochordata – TunicatesUrochordata – Tunicates Cephalochordata – LanceletsCephalochordata – Lancelets Vertebrata – VertebratesVertebrata – Vertebrates

V.Chordata A.Urochordata - Tunicates 1.Ascidiacea (Class) – Sea squirts Only sessile chordatesOnly sessile chordates Solitary (single or clumped)Solitary (single or clumped) ColonialColonial Body covered by tunic (gelatinous outer covering)Body covered by tunic (gelatinous outer covering) Active suspension feeders (filter feeders)Active suspension feeders (filter feeders) Water pumped in through incurrent siphon and out through excurrent siphonWater pumped in through incurrent siphon and out through excurrent siphon Particles filtered out by feeding basket (pharynx)Particles filtered out by feeding basket (pharynx) Planktonic tadpole larvaPlanktonic tadpole larva Possesses all four chordate characteristicsPossesses all four chordate characteristics Doesn’t feed – resorbs notochord and tail at settlementDoesn’t feed – resorbs notochord and tail at settlement

Fig 7.48