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Cnidarian Reproduction
Asexually – budding (polyp form)Sexually –have separate male
and female medusae that produce gametes that join through external fertilization to produce polyps.
Flatworms - Platyhelminthes
Bilateral Symmetry Free-living in freshwater or
parasitic in a hostHas all three layers (endoderm,
mesoderm, ectoderm)Acoelomate – no body cavity.
An Important Group
Many nasty parasitic infections.
DugesiaTapeworms
Flukes
Flatworm Feeding
Free living flatworms are scavengers.
Parasitic flatworms use specialized structures (usually with hooks) to attach to a host.
Respiration & Excretion
Excretion - Flame cells remove excess water
Respiration - Oxygen diffuses into body cells directly.
Flatworm Nervous Systems
First appearance of cephalization.
Primitive brain.Eyespots
Flatworm Reproduction
Sexually - Hermaphrodites – internal fertilzation.
Asexually – fission – when damaged, regenerates new body parts.
Proglottids – found in tapeworms – each is shed off individually.