Lecture Exam I

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Lecture Exam I

• Cambrian radiation / phylogeny 2 papers
• Systematics intro
• Protista 10 phyla
• Animalia Porifera, Cnidaria
• 20 questions
• Short answer, essay, life cycle sketch

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Phylum Cnidaria

• 3 Classes
• Anthozoa
• Scyphozoa
• Hydrozoa

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Characteristics

• Diploblastic metazoan
• Ectoderm and endoderm separated by acellular
  mesoglea
• Nervous system simple nerve net, neurons

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Development

• Planula larvae
• ciliated, motile, gastrula larva

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Radial symmetry

• Modified into
• biradial, quadradial,
• etc

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Gastrovascular cavity

• Saclike, partitioned, or branched w/ one opening
  
• mouth and anus

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Alternating life history forms polyp and medusa
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Polyp

• Radial symmetry
• Oral end hypostome or manubrium in hydrozoans
• flat pedal disc in anthozoans
• Tentacles surround mouth

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PolypGastrovascular cavity

• Circulation, digestion, distribution of nutrients
• Hydrozoans coelenteron is single tube
• Scyphozoans four longitudinal mesenteries
• Anthozoans compartmentalized by mesenteries

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Polyp support

• Hydrostatic, water-filled coelenteron
• Anthozoans - bits of sediment and shell fragments
  in column wall for support
• Hydrozoans - flexible horny perisac (periderm) of
  chitin from epidermis

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Polyp movement

• Retractor muscles longitudinal fibers along
  mesenteries
• Circular muscles sphincters
• in tentacles and oral disc
• Most polyps sedentary or sessile
• Creep slowly w/ pedal disc musculature
• http//www.youtube.com/watch?v-UI531GMRTM

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Medusa

• All cnidaria except Anthozoa
• Bell-, dish- or umbrella-shaped
• Exumbrella convex upper (aboral) surface
• Subumbrella concave lower (oral) surface
• Mouth at center

Free-floating, mouth down
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Medusa

• External surface epidermis
• Internal surface gastrodermis
• Coelenteron central extends to radial canals
• Usually four radial canals, tentacles, stomach
  divided by mesenteries into four gastric pouches

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Nematocysts

• Stinging structures

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Nematocysts multiple types

• Generic nematocyst (all)
• Double-walled capsule w/ toxic mixture of phenols
  proteins
• Spines or barbs for penetration, anchor in victim
• Spirocyst (Anthozoa)
• Spring-like mechanism
• Adhesive tubules wrap around and stick to victim
• Ptychocyst (tube anemones)
• Create capsule tubule

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Feeding and digestion

• Tentacles capture prey, carry to mouth, ingest
  whole
• Extracellular digestion in coelenteron
• enzyme-producing cells

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Reproduction and DevelopmentHydrozoa

• Polyps asexual budding

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Reproduction and DevelopmentHydrozoan

• Free-living hydromedusa
• Dioecious, release sperm or eggs

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Reproduction and DevelopmentScyphozoa

• Asexual reproduction small polyp scyphistoma
• Medusa from scyphistoma
• Immature medusa ephyra
• Most species dioecious

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Reproduction and DevelopmentAnthozoa

• Exclusively polyps
• Asexual reproduction
• Fission
• Pedal laceration pedal disc spreads, anemone
  moves, leaves small fragments
• develop into adult

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Class Hydrozoa

• Hydroids and hydromedusa

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Hydrozoa Portuguese Man-of-war Physalia
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Class Anthozoa

• Anemones, corals, sea pens
• Exclusively marine
• Octocorals
• Soft corals
• Gastraxonacea
• Helioporaceans
• Sea pens and sea pansies
• Protoalcyonaria
• Stoloniferans
• Telestaceans

Sea pen
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Class Anthozoa

• Anemones and true corals
• True sea anemones
• True corals (stony corals)

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Class Anthozoa

• Black or thorny corals
• Ceranthids or tube anemones

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Class Scyphozoa

• Jellyfish

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Box jelly
Chiropsalmus