Cnidaria

• Scyphozoa (cup animals):

  • Asexual replication by strobilation
  • Large in size
  • All marine habitat
  • Medusoid morphology
  • Actively swim using mesoglea
  • Carnivorous diet
  • Gastrovascular canal for digestion
  • Rhopalia (statocysts & ocelli), sensory lappets
  • Gonads develop in gastrodermal tissue
  • Planula larva attaches to substrate to form scyphistoma (polyp form) and feeds there
  • Forms more scyphistoma through budding
  • Strobilation leads to ephyra and adult scyphozoan
• Cubozoa (cube animals):

  • Medusa with boxlike body
  • Rhopalia bear complex lensed eyes
  • Small in diameter, long tentacles
  • Found in tropical and subtropical habitats
  • Predominantly medusa morphology
  • Cuboidal swimming bell with 4 tentacles
  • Carnivorous diet
  • Well-developed eyes that can form images
  • Asexual production with polyp budding to more polyps that develop into medusas
• Hydrozoa (water animals):

  • Gastrodermal tissue lacks nematocysts, no cells in mesoglea, restricted to epidermis
  • Polyp can be medusa, sometimes mostly medusa
• Hydroidolina:

  • Some marine, some freshwater habitats
  • Smaller than scyphozoan medusae
  • Medusoid as adults with thick mesoglea
  • Gonochoristic sex
  • Planula produces polyps (zooids), polymorphic or dimorphic depending on types of zooids
  • Zooids are from planular larva and stay in a colony to help each other
  • Medusa can revert back to polyp under stressful conditions
• Siphonophora:

  • Medusoid and polyp (gastrozooids, gonozooids, dactylozooids) simultaneously
  • Mesoglea reduced in pneumatophores
  • Nectophores have no mouth and tentacles
  • Phyllozooids or bracts have lots of nematocysts
  • Colonial hydrocorals secrete calcareous skeleton in warm waters
  • Dactylozooids dominant with cormidia, gonozooids, dactylozooids, phylozooids, gastrozooids
• Hexacorallia (scleractinian corals):

  • 6 tentacles & primary mesenteries, never polymorphic
  • Solitary, found in clear warm waters with low plankton productivity
  • Siphonoglyphs for excreting CaCO3 skeletons
  • Carnivores with zooxanthellae endosymbionts
• Octocorallia:

  • 8 tentacles, polymorphic
  • 1 siphonoglyph, pinnate tentacles for capturing food
  • Found in various habitats
  • Fatty-acid metabolism for diet
• Staurozoa

  • small
  • cold shallow waters
  • no medusa stage
  • catch prey with 8 tentacles w/ nematocysts
  • Release gametes into water - embryos develop into planulae (no cilia, only muscle) - substrate - feeding tentacles and gonads
• Myxozoans

  • Extracellular, spore forming
  • Polar filaments, polar capsules
  • Longitudinal muscles
  • lacks digestion
  • lacks nervous
• Anthozoa

  • No medusa stage, no operculum and cnidocil, circular mitochondrial DNA, ciliated groove
  • Marine
  • polyp; bilateral symmetry
  • Gametes produced in polyp - planula larva from fertilized egg - metamorphosis - another polyp formed; transverse fission pr pedal laceration
  • Mostly gonochoristic, sometimes hermaphroditicz
  • Carnivorous
  • Nematocyst studded tentacles - central mouth opening - pharynx (siphonoglyphs); acontia
  • Acontia; acrorhagi; catch tentacles
  • Hydrostatic skeleton, Circular and longitudinal
  • Swim for a few millimeters, mostly stationary
• Hydrocorals

  • colonial, secrete calcareous skeleton
  • warm waters
  • dactylozooids