UWRF zoology exam 2 Questions Perfectly Answered!!

3 germ layers - ectoderm, MESODERM, endoderm What does the mesoderm form? - True muscle tissue Acoelomate - no body cavity coelomate (eucoelomate) - True body cavity completely surrounded by mesoderm Pseudocoelomate - false body cavity symmetry of platyhelminthes - bilateral symmetry (first appearance) Platyhelminthes nervous system - -Anterior cerebral ganglion and nerve cords -Eyespots Platyhelminthes osmoregulation - Flame cells Simple diffusion Flame cells - In flatworms, specialized cells that remove excess water from the body. Platyhelminthes taxonomy - Class turbellaria Class monogenea Class Trematoda Class cestoda Class Turbellaria - Planariaturbellaria digestive system - incomplete, eversible pharynx turbellaria reproduction - Monoecious, fragmentation (asexual) syngamy (sexual) Monogenea reproduction - Sexual only Class Monogenea - ectoparasites Haptor Class Trematoda - parasitic flukes Clonorchis, human liver fluke Primary host- vertebrate Intermediate host- snail Trematoda reproduction - Monoecious Asexual and sexual Life cycle of Clonorchis - 1. adult lives in human bile duct (large mammal is primary host) 2. eggs are expelled in the feces 3. eggs are consumed by a snail (intermediate host) 4. inside the snail are 3 larval stages a. miricidium (hatches out of egg) b. sporocyst c. redia 5. cercaria formed by the redia escapes from the snail 6. cercaria enters a fish 7. cercaria forms a metacercarial cyst inside a muscle of the fish8. large mammal consumes the fish and an adult hatches out of the metacercarial cyst