BIOL108 Lecture Notes - Lecture 20: Filter Feeder, Body Plan, Eumetazoa

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Activity: origin of multicellularity in animals (required), online quiz (required). They are heterotrophic protists, single agellum surrounded by collar of microvilli ( ngerlike projections of cell membrane). The cell morphology is very similar to that of sponges (porifera). Evolution of multicellularity: hypothesis- ball-shaped colony of choano agellates may have evolved into a simple animal with endo- and ectodermal layers. If cooperative aggregations of cells are able to survive better an produce more o spring than their unicellular counterparts, then these various evolutionary pathways could all be possible. Multicellularity selective advantages: avoid getting eaten, improved feeding with size and coordination, specialization of tasks (division of labour). Multicellularity costs: most cells don"t reproduce- support few that do. Requires cooperation- opportunities to cheat (ex: cancer cells). Multicellularity evolved independently in several lineages (protists, fungi, plants, animals). Di usion: random motion of molecules from high to low concentration. Bulk ow: active transport of oxygen, nutrients, and other molecules in bulk.