BIOL108 Lecture Notes - Lecture 21: Coral Bleaching, Polytomy, Dirham

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

Document Summary

Diploblastic means that they have 2 layers, ectoderm and endoderm. Organs are a collection of tissues that perform a specialized task. They are jelly sh, hydras, sea anemones, and coral. Polyp (sessile form): oral end upwards, attached to a substrate. Medusa (motile form): oral end downwards, moves freely through the water via hydrostatics skeleton. Cnidarians are named for unique cells = cnidocytes. They contain a variety of structures, most common is nematocyst. If someone touches a spike, the nematocyst shoots out. Toxins produced by some cnidarians dangerous to humans. Reefs constructed by corals provide shelter and food for many marine species. Anthozoa secrete calcium carbonate to form a hard skeleton. Coral bleaching due to loss of zooxanthellae may be rst sign of ecological meltdown. They have a head, but not a well developed brain. Can range from a worm to an octopus. Phylum platyhelminthes: acoelomate, don"t have coelom, they are a mass of tissue.