BIOL108 Lecture Notes - Lecture 21: Obelia, Bilateria, Body Plan

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

Document Summary

Biol 108 - lecture #21 - phyla cnidaria, acoela, platyhelminthes. Eumetozoa: true, differentiated tissues (muscles and nerves: diploblastic, contains organs (collection of tissues specialized for different task) Radial symmetry: right before bilateral symmetry evolved. Includes the jellyfish, hydras, sea anemones, corals: ~10 000 species, 99. 9% marine, simple body plan. Carnivorous: named for their unique cells cnidocytes. Most common type: nematocyst: defense and prey capture. Captures prey and digests in gastrovascular cavity. Ecology and importance: many cnidarians house symbiotic algae (zooxanthellae, important predators of zooplankton or larval fish, toxins produced by some cnidarians are dangerous to humans, constructing reefs by corals. Anthozoa: secrete calcium carbonate to form hard skeleton: human economy, coral bleaching = ecological meltdown. Due to the loss of the symbiotic algae. Hydrozoan obelia life cycle: polyp attached to substrate, larvae has cilia, mostly diploid, except for gametes. Clade bilateria: bilateral symmetry, varying degrees of cephalization. Lots of neural ganglia at the back of the head (acts as brain)