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Keystone Species

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Keystone Species Echinodermata Echinoidea (Sea urchins, Sand dollars) Approximately 1000 species Includes heart urchins, sea biscuits Round, rigid test with movable ... – PowerPoint PPT presentation

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Title: Keystone Species


1
  • Keystone Species

2
  • Echinodermata
  • Echinoidea (Sea urchins, Sand dollars)
  • Approximately 1000 species
  • Includes heart urchins, sea biscuits
  • Round, rigid test with movable spines and
    pedicellariae
  • Spines and tube feet used for locomotion
  • Tube feet in shallow ambulacral grooves along
    outside of test
  • Complete digestive system
  • Mouth on bottom, anus on top
  • Herbivores
  • Feed on seaweeds and seagrasses (especially
    drifting) plus attached encrusting organisms
  • Mouth includes Aristotles lantern

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

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Enypniastes eximia
9
  • Echinodermata
  • Crinoidea (Feather stars, Sea lilies)
  • Suspension feeders
  • Mouth oriented upward
  • Capture particles with tube feet/mucus
  • Ciliated ambulacral grooves transport food to
    mouth
  • Cling to substrate with cirri
  • Capable of swimming Video Clip
  • Feather stars Unstalked
  • Cosmopolitan, but especially abundant in warm
    water
  • Capable of swimming
  • Sea lilies Stalked
  • Uncommon, restricted to deep water

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  • Lophophorates
  • Three phyla all animals possess lophophore
  • Ciliated hollow tentacles arranged in a horseshoe
  • Suspension feeders
  • Bilateral symmetry, coelom (body cavity),
    U-shaped gut
  • Bryozoa/Ectoprocta Bryozoans
  • Colonies consist of interconnected individual
    zooids
  • Encrusting and lacy forms (CaCO3 tests)
  • Retractable lophophore
  • Phoronida Phoronids, Horseshoe Worms
  • Worm-shaped
  • Agglutinated sediment tubes attached to hard
    substrate in shallow water
  • Brachiopoda Lamp Shells
  • Abundant in fossil record
  • Superficially resemble clams, but shells are
    dorsal-ventral, not left-right as in mollusks
  • Many attached to substrate with pedicle (short
    stalk)

13
Bryozoa
14
  • Lophophorates
  • Three phyla all animals possess lophophore
  • Ciliated hollow tentacles arranged in a horseshoe
  • Suspension feeders
  • Bilateral symmetry, coelom (body cavity),
    U-shaped gut
  • Bryozoa/Ectoprocta Bryozoans
  • Colonies consist of interconnected individual
    zooids
  • Encrusting and lacy forms (CaCO3 tests)
  • Retractable lophophore
  • Phoronida Phoronids, Horseshoe Worms
  • Worm-shaped
  • Agglutinated sediment tubes attached to hard
    substrate in shallow water
  • Brachiopoda Lamp Shells
  • Abundant in fossil record
  • Superficially resemble clams, but shells are
    dorsal-ventral, not left-right as in mollusks
  • Many attached to substrate with pedicle (short
    stalk)

15
  • Lophophorates
  • Three phyla all animals possess lophophore
  • Ciliated hollow tentacles arranged in a horseshoe
  • Suspension feeders
  • Bilateral symmetry, coelom (body cavity),
    U-shaped gut
  • Bryozoa/Ectoprocta Bryozoans
  • Colonies consist of interconnected individual
    zooids
  • Encrusting and lacy forms (CaCO3 tests)
  • Retractable lophophore
  • Phoronida Phoronids, Horseshoe Worms
  • Worm-shaped
  • Agglutinated sediment tubes attached to hard
    substrate in shallow water
  • Brachiopoda Lamp Shells
  • Abundant in fossil record
  • Superficially resemble clams, but shells are
    dorsal-ventral, not left-right as in mollusks
  • Many attached to substrate with pedicle (short
    stalk)

16
  • Chaetognatha (Arrow Worms)
  • Important components of the plankton
  • Voracious carnivores
  • Sit and wait predators
  • Eat zooplankton (small crustaceans, larvae, eggs)

Fig 7.41
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  • Enteropneusta (Acorn Worms)
  • Hemichordates
  • Possible evolutionary transition between
    invertebrates and chordates
  • Share some but not all characteristics with
    chordates
  • Deposit feeders
  • Many construct U-shaped burrows and process large
    quantities of sediment
  • Proboscis secretes mucus used to collect organic
    material

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  • Chordata
  • Characteristics
  • Dorsal hollow nerve cord
  • Pharyngeal gill slits
  • Notochord
  • Postanal tail
  • Three subphyla
  • Urochordata Tunicates
  • Cephalochordata Lancelets
  • Vertebrata Vertebrates

21
  • Chordata
  • Urochordata - Tunicates
  • Ascidiacea (Class) Sea squirts
  • Only sessile chordates
  • Solitary (single or clumped)
  • Colonial
  • Body covered by tunic (gelatinous outer covering)
  • Active suspension feeders (filter feeders)
  • Water pumped in through incurrent siphon and out
    through excurrent siphon
  • Particles filtered out by feeding basket
    (pharynx)
  • Planktonic tadpole larva
  • Possesses all four chordate characteristics
  • Doesnt feed resorbs notochord and tail at
    settlement

22
Fig 7.48
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