BIOL 111 Lecture 12: BIOL 111 – Lecture 12 – Embryonic Development_ Annelids (Cont’d) & Mollusks_ How The Nervous System Works

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Biol 111 lecture 12 embryonic development: annelids (cont"d) & mollusks: how the. Lecture date/time: oct 20th, 2015 / 10:35-11:25 am. Polychaeta: many hairs , marine worms, they are the largest group. Clitellata: oligochaeta = few hairs (earthworms), hirudinea (leeches) Mainly terrestrial, detritivores (aerate soil), have few setae, they"re hermaphroditic clitellum (ring like structure) secretes a mucus cocoon for embryo development, they have no specialized larval stage (born/come out of cocoon as worms) Exchange sperm during mating and then store it (time of fertilization is different than copulation) female function can control reproduction (sperm competition) Hirudinea: mainly freshwater, parasitic and carnivorous, no setae (anterior and posterior suckers), hermaphroditic (clitellum, no specialized larval stage) ^they also have medical benefits: (hirudin) to reduce swelling. Branch in the protostome animals ( mollusks = mollusca) 100,000 + species, 2nd largest animal group (after arthropods), terrestrial or aquatic. Highly diverse: morphology, modes of nutrition, reproduction, response to environment.