1BIS2C Winter 2012 (Ward)Lecture 34. Chordata, Part 1Today's lecture (16 March)•finish Echinodermata•introduction to Chordata•major features•early chordate evolution•origin of vertebrates•jawless and jawed fishMonday lecture•tetrapods, especially amniotes•convergent evolutionBIS2C Winter 2012 Review Session (Tuesday, 20 March)•1:00 pm – 3:00 pm•123 Sci LecPosted on Smart Site (under Resources/Exam Study Guides):•Final Exam Study Guides (Metazoans; Microbes/Plants/Fungi) BIS2C: Room assignments for final examSec. A March 21st, 6:00-8:00 pmChem 194A-LHaring Hall 2205M-WeBainer 1132Wi- ZSec. B March 24th, 6:00-8:00 pmYoung 198A-KHaring Hall 2205L-SWellman 106T- ZCalifornia sea otters eat urchins.Sea urchins consume kelp.When sea urchins are abundant they can destroy dtk lftunderwater kelp forests.Clicker Question 1Sea otters can be considered a “keystone species” in this system becausea. The kelp forests flourish when otters are removed.b. Their presence or absence has a large effect on ecosystem structure.c. They provide the key to understanding why sea urchins eat kelp.d. Their abundance is positively correlated with the abundance of other animals in the environment.e. They have evolved to eat sea urchins.Sea cucumbers (Holothuroidea)•soft-bodied and slug-like (ossicles much reduced)•greatly elongated oral/aboral axis, secondarily bilateral•grazers, suspension feeders
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