Class Anthozoa characteristics

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Class Anthozoa - characteristics

• 6000 species
• Medusa stage is absent
• Polyp is responsible for both sexual and asexual
  reproduction
• Size range from 0.5cm to 1m.
• Only cnidarian class that has all three types of
  cnidae (nematocysts, spirocysts and ptychocysts).

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Anthozoa General Anatomy

• 1. Tentacles
• 2. Pharynx
• 3. Siphonoglyph
• 4. Gastrovascular cavity

5.-7. Septae 8. Gonads 9. Pedal disk
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Anthozoa Retractor muscles
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Anthozoa nervous system

• Nerve net for epidermis (tentacles)
• Nerve net for gastrodermis (body)

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Anthozoa Feeding and Digestion
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Anthozoa Gas Exchange and Excretion

• Diffusion from tentacles and body cells
• Siphonoglyph directs currents to remove waste.

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Anthozoa - Reproduction

• Asexual
• Fission
• Fragmentation
• Budding
• Some asexual larval formation (Planula larvae) in
  corals

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Class Anthozoa

• Subclass Hexacorallia

• Order Actiniaria (true anemones)
• Never colonial
• No calcareous skeleton
• Some with zoozanthellae

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Class Anthozoa

• Subclass Hexacorallia

• Order Scleractinia (stony corals)
• Mostly colonial
• Calcareous skeleton
• No siphonoglyphs
• Half with zoozanthellae

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Corals

• Corals flourish in nutrient-poor, clear, tropical
  waters.
• Symbiotic photosynthetic dinoflagellates
  (zoozanthellae) help corals obtain enough
  nutrients to grow rapidly.
• The corals provide protection and nutrients for
  the dinoflagellates, which in turn provide the
  products of photosynthesis to the corals.

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Corals

• Corals flourish in nutrient-poor, clear, tropical
  waters.
• Symbiotic photosynthetic dinoflagellates help
  corals obtain enough nutrients to grow rapidly.
• The corals provide protection and nutrients for
  the dinoflagellates, which in turn provide the
  products of photosynthesis to the corals.

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• The Great Barrier Reef along the northeastern
  coast of Australia is 2,000 km long and 150 km
  wide.

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Coral reef distribution

• Global warming and nutrient runoff are
  threatening coral reefs throughout the world.

www.geology.iupui.edu/academics/CLASSES/g130/reefs
/images/f1519th.gif
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Class Anthozoa

• Subclass Hexacorallia

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Class Anthozoa

• Subclass Octocorallia (octocorals)
• 8 hollow pinnate tentacles
• Single siphonoglyph
• Scleroblasts secrete sclerites

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Class Anthozoa

• Subclass Octocorallia

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Class Anthozoa

• Subclass Ceriantipatharia

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Class Anthozoa

• Subclass Ceriantipatharia

• Order Ceriantheria (tube anemones)
• Large solitary polyp
• Lives in tube
• Long thin tentacles

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Class Scyphozoa - characteristics

• 200 species
• Medusa stage is present and is the dominant stage
• Polyp is a scyphistomae
• Size range from 2 cm to 2 m.

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Scyphozoa Polyp Anatomy

• Tentacles
• Periderm (tube)
• Septal funnels instead of septae (not shown)

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Scyphozoa Medusa Anatomy
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Scyphozoa nervous system

• Nerve ring for bell
• Nerve net for manubrium, oral arms, and tentacles.

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Syphozoa Feeding, Digestion, Gas Exchange and
Excretion

• Similar to Anthozoa

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Scyphozoa - Reproduction

• Asexual
• Budding

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Class Scyphozoa
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Class Cubozoa

• Box jellies
• Each polyp produce a single medusa
• Medusa nearly square in X-section
• has velarium like hydrozoan medusae
• extremely toxic
• 4 sets of eyes
• Light sensor
• Image forming eyes
• bottom with pupil

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Class Hydrozoa - characteristics

• 3000 species
• Mostly colonial medusozoans
• Life cycle may include polyps, medusae or both
• Unlike other Cnidarians, nematocysts are found
  only on the epidermis not in the gastrovascular
  cavity.
• Some nematocysts funtional equivalent to
  Anthozoan spirocysts.
• Polyps usually tiny

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Hydrozoa Polyp Anatomy
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Hydrozoa Medusa Anatomy

• Statocysts and ocelli may be present along edge
  of bell

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Hydrozoa Colony Anatomy
Thecate colony
Athecate colony
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Hydrozoa nervous system

• Nerve ring for bell on medusae
• Nerve net for manubrium, body, and tentacles.

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Hydrozoa Feeding, Digestion, Gas Exchange and
Excretion

• Similar to Anthozoa

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Hydrozoa - Reproduction

• Asexual
• Budding

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Class Hydrozoa

• Order Hydroida
• Suborder Anthomedusae (Athecate)

• Polyps solitary or colonial
• Gonozooids lack exoskeleton (athecate)
• Free meduse tall and bell shaped
• Gametes form on subumbrella

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Class Hydrozoa

• Order Hydroida
• Suborder Leptomedusae (Thecate)

• Polyps always colonial
• Feeding zooids encased in exoskeleton
• Free medusae not usually present
• Gamete for on radial canals in subumbrella

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Class Hydrozoa

• Order Trachylina

• Polyp generally absent
• Tentacles arise above edge of bell

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Class Hydrozoa

• Order Trachylina

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Class Hydrozoa

• Order Siphonophora

• Floating or swimming colonies
• Attached modified medusae
• In all but one group, the end of the axial polyp
  forms a pneumatophore for flotation.

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Class Hydrozoa - Athecate orders

• Order Siphonophora
• Nectophores (attached medusae-like zooids)
  provide propulsion

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Class Hydrozoa Athecate orders

• Order Siphonophora
• Below the nectophores are three types of zooids
• Dactylzooid grasping and prey-capture
• Gonozooid - reproduction
• Gastrozooid digestion

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Class Hydrozoa

• Order Chondrophora

• Colonies with gastroozoids, dactylzooids and
  gonozooids or super organism?
• Zooids attached to sail-like float