Post on 19-Dec-2015
I. Life evolved in the oceans
• A. Least stressful environment
• B. Moderating temperature• C. Closest to osmotic
properties• D. Buoyancy not a problem• E. Gametes can be released
with no problem• F. Abundant food
II. Parazoa-Sponges (Porifera)A. Introduction
• 1. do not possess true tissues• 2. cell layers are loose associations• 3. if you take a sponge and pass it through a screen-it can reassemble• 4. layers are dependent upon one another-but not as dependent as
higher levels• 5. very sessile organisms• 6. lack muscles, nerves-individual cells can react to the environment
B. Body Plan• 1. epidermis with porocytes• 2. mesohyl with amoebocytes• 3. Inner cell layer with choanocytes
4. Endoskeleton of spicules
• a. some spicules are calcium carbonate
• b. some spicules are proteinaceous
• c. found in mesohyl• d. can be used to
classify sponge
5. Choanocytes power the sponge
• a. 275 gallons needed to produce three ounces of new sponge
• b. Flagella creates water currents
• c. Microvilli filter water as it comes through
C. Reproduction of sponge
• 1. asexual fragmentation• 2. production of gemmules• 3. sexual reproduction-
hermaphroditic
A. Basic body plan
• 1. diploblastic• 2. gastrovascular
cavity• 3. radial symmetry• 4. tentacles• 5. cnidoblasts• 6. mesoglea• 7. two basic forms-
polyp and medusa
Hydra videos
• http://www.schooltube.com/video/8b4ca7db15144b83b7c6/Hydra