Porifera, Ctenophora, Cnidaria
- Created by: Abbie Storah
- Created on: 14-03-16 11:47
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- Porifera, Ctenophora & Cnidaria
- Porifera 'pore-bearer'
- 9,000-15,000 species - 50 in freshwater, others marine
- Polar to tropics - most prefer clear, quiet water
- Sessile
- Low-energy
- Filter feeders
- Loosely organised - no symmetry, muscles or nervous system
- Body plan = aggregation of cells built around water canal system - chimney-like
- Water currents: enter through ostia, leave via osculum at top
- Few types of cells including choanocytes ('funnel cell')
- Jelly-like extracellular matrix
- Sexual reproduction
- Sperm sent out via osculum
- Ciliated larvae, often free swimming
- Settle and develop into juveniles
- Asexual reproduction by budding
- 3 classes: demospongia hexactinella calcarea
- Ctenophora 'comb carriers'
- Comb jellies
- 2 cell layers separated by gelatinous mesoglea
- Common in open sea
- ~150 species
- Complete through-gut
- Ctenes - cells with plates of cilia which move animal
- Cnidaria
- Genera to remember: Actinia, Aurelia & Hydra
- ~11,000 species
- All aquatic
- Almost all marine
- Diploblastic - 2 cell layers separated by mesogloea
- Muscle fibres and nerve nets
- Cnidocytes ('stinging cells') - catch prey with little energy
- LIFE CYCLE
- Sessile polyp
- Asexual
- Individual polyps may bud to form colonies
- Motile medusae
- Shed eggs and sperm into water
- Sessile polyp
- Sometimes called coelenterates
- 4 EXTANT CLASSES
- Anthozoa ('flower animals')
- Sea anemones, hard corals, soft corals
- All marine
- Lack medusa stage
- Hydrozoa ('water animals')
- Diverse life cycles
- Polyp commonly dominates life cycle
- Most are colonial
- Scyphozoa (jellyfish)
- 'Cup-shaped'
- All marine
- Medusa often large
- Polyps small and in-conspicuous
- Cubozoa (box jellyfish)
- Square bell rather than round
- Eyes with a retina, lens, iris and visual behaviour
- Some extremely venemous
- Anthozoa ('flower animals')
- Porifera 'pore-bearer'
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