Most people may not realize that coral reefs are centered around actual organisms. Coral polyps are invertebrates (related to sea anemones and jellyfish) surrounded by a limestone skeleton called a calicle. The polyps attach to rocks, bud and clone, and begin the basis of a coral reef. Once attached to one another, forming a colony, the polyps act as a single organism. The joining of colonies over hundreds and thousands of years is what form coral reefs. A single polyp can live for 2 years to hundreds of years and colonies can survive 5 years to several centuries. Since coral polyps are actually translucent animals, the bright colors come from the association with zooxanthellae algae.
When stressed by such things as temperature change or pollution, corals will evict their boarders, causing coral bleaching that can kill the colony if the stress is not mitigated
The destruction of coral reefs is becoming an issue leaving coral in an endangered status.
Corals are so sensitive to climatic change that scientists study coral reef fossils to construct highly detailed chronologies of prehistoric climate patterns.
Photosynthesis from the algae support the coral for the most part, but they also posses barbed, venomous tentacles that can be used to capture zooplankton and small fish. Though coral covers about 1% of the ocean floor, they support about 25% of all marine creatures. Within 30 years, threats to coral reefs (pollution, sedimentation, global warming, etc.) could kill 30% of the remaining coral reefs.
- Study shows adaptive capacity of reef corals to climate change may be widespread (eurekalert.org)
- Why climate change might not spell death for the Reef (eco-business.com)
- Weird ocean current may create coral refuges (msnbc.msn.com)