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 host Has all three layers (endoderm, mesoderm, ectoderm) Acoelomate – no body cavity.
An Important Group
Many nasty parasitic infections.
Dugesia
Tapeworms 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.