During the last several days we have had the opportunity to explore the underwater habitat of the Caribbean with snorkeling expeditions. Today was our third outing, and we were at an idyllic island known as Blanquilla, in a remote location off the coast of Venezuela.

The island has an excellent white sandy beach and a huge diversity of fish and corals in the waters. This is a close-up view of the complex pattern of brain coral. Corals are a symbiotic relationship between an animal, the coral polyp and an organism known as zooxanthella. Zooxanthella are a group of organisms that live within animals and all are yellow-brown in color (xanth= gold).

The coral polyp produces nitrogen as a waste product, which is used by the plant like zooxanthella as a fertilizer. When doing photosynthesis, the zooxanthella reduces the amount of carbon dioxide in the water and this aids in the polyp's ability to produce calcium carbonate for its skeleton. Corals are a true mutualistic relationship between a plant and an animal.