Defense Mechanisms

The Importance of Defense Mechanisms

Corals are sessile
- Fixed at a certain position, attached to a substrate (such as a rock, or between sand)
- Corals are sessile, colonial animals — remaining stationary for most of their life cycle — which makes the ocean a very dangerous place
- Their vulnerability has lead to some of the most lethal toxins found in nature today
  - chemical defense is vital

Toxicity was naturally selected for
- Corals that were often preyed upon by fish now have higher toxicity levels, for their own protection
- The low nutritional value of some corals made them less susceptible to predation, so the lower the nutritional value, the lower the toxicity level

Nematocytes
- Stinging cells used to capture small prey, kill of neighboring corals in a continuous battle for space
- Most corals possess these in addition to everything else

Cnidocils
- Activated when a predator touches it
- Discharges a nematocyst
Nematocysts ^[8]
- Discharge by firing a barb into the predator, leaving a hollow filament through which poisons are injected to immobilize the prey
- Tentacles move the prey to the polyp mouth

↑ Van Der Weijden, Sander. "Chemical Defense Mechanisms." Chemical Defense Mechanisms. Coral Publications, n.d. Web. 27 Feb. 2013 [1]
↑ Chemical Defense Mechanisms on the Great Barrier Reef, Australia – Gerald J. Bakus. Science. New Series, Vol. 211, No. 4481 (Jan. 30, 1981). pp. 497-499
↑ Ferrer, Ryan P., and Richard K. Zimmer. "Neuroecology, Chemical Defense, and the Keystone Species Concept." The Biological Bulletin 213.3 (2007): 208-25. Print.
↑ Marcus, Erin N. "Marine Toxins." Marine Toxins. Ed. James F. Wiley, II. UpToDate, Inc., 17 Dec. 2012. Web. 27 Feb. 2013.
↑ Rosenberg, Eugene, Omry Koren, Leah Reshef, Rotem Efrony, and Ilana Zilber-Rosenberg. "The Role of Microorganisms in Coral Health, Disease and Evolution." Nature Reviews Microbiology 5.5 (2007): 355-62. Print.
↑ Lema, Kimberley A., Bette L. Willis, and David G. Bourne. "American Society for MicrobiologyApplied and Environmental Microbiology." Corals Form Characteristic Associations with Symbiotic Nitrogen-Fixing Bacteria. American Society for Microbiology, 17 Feb. 2012. Web. 27 Feb. 2013.[2]
↑ *Stewart, Hannah L., Sally J. Holbrook, Russell J. Schmitt, and Andrew J. Brooks. "Symbiotic Crabs Maintain Coral Health by Clearing Sediments." Coral Reefs 25.4 (2006): 609-15. Print.[3]
↑ Kass-Simon, G., and A.A. Scappaticci, Jr. "The Behavioral and Developmental Physiology of Nematocysts." Canadian Journal of Zoology 80.10 (2002): 1772-794. Print.