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.