BIOL 211 Lecture Notes - Lecture 9: Lophotrochozoa, Lophophore, Triploblasty
Document Summary
Live in marine, freshwater, and damp terrestrial habitats. Range in size from microscopic to over 20 meters long. Incomplete digestive system (gastrovascular cavities) or no digestive system. They have no open cavity, just tissue layer, tissue layer, etc. Prey items are brought to the mouth by a muscular protractible pharynx. Food is digested in an incomplete digestive system gastrovascular cavity. Host is necessary to complete the life cycle. Is the amount of body dedicated to reproduction free-living have more gastrovascular cavities parasites have way more reproductive systems in them (because they live in a host) Very mobile larval stages (sometimes multiple larval stages to move between hosts) Reproduction of organs or organ systems (ex, no digestive tract) External covering that is tough or can camouflage it from host"s immune system) Many species have complex life cycles involving multiple hosts (intermediate and final hosts) Parasites can change the behavior of the host to increase likelihood of transmission.