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"World Oceans Day is a global day of ocean celebration and collaboration for a better future ... to honor, help protect, and conserve the world's oceans." #WorldOceanDay #WorldOceansDay  #WorldOceanDay #WorldOceansDay - Photo courtesy: Axel Schwannaeusser Coral reefs are not only extremely diverse marine ecosystems, hosting many species, they are also eye candy for divers and snorkelers. Some major facts about corals, resuming a recent article by Nicole Helgason, PADI Dive Instructor at ScubaDiverLife. Coral reefs are not only extremely diverse marine ecosystems, hosting many species, they are also eye candy for divers and snorkelers.
Some major facts about corals, resuming a recent article by Nicole Helgason, PADI Dive Instructor at ScubaDiverLife. 1. Corals are colonial animals formed by many identical polyps. The individual polyps look like sea anemones, with similar body structure: mouth, stomach and tentacles. During the nights these tentacles are exposed and waiting for the meals to pass by. Some have longer tentacles too, to catch food, or sting other corals that encroach on their territory. 2. There are two general categories, hard corals, where polyps form hard skeletons and soft corals, where jelly-like or rigid, spiny structures hold together soft coral polyps. Another difference is that hard corals are built on a six-fold symmetry, while soft corals are built on an eight-fold symmetry. 3. Hard corals live in tropical, sunny waters, where light penetrates the ocean water to a depth of approximately 230 feet (70 m). Optimal water temperatures for corals are between 73 and 84 F (23 and 29 C), although some can tolerate higher temperatures for short periods. Coral polyps live in symbiotic relationship with photosynthetic marine algae. The coral provides home and protection for the algae and, in exchange, the algae absorb sunlight and produce energy for the polyp. They also give the coral its color. Polyps can also get energy from ingesting plankton and food particles, but being fixed in place, their energy from food consumption is limited. When too much light or high water temperatures stress the polyps, the stressed polyp expels the zooxanthellae algae. If the water temperatures don’t fall quickly enough, the polyp will die without its important symbiont. This is the reason behind the coral bleaching. 4. Corals are regional, and the Australian Institute of Marine Science's website is a great tool in regional coral identification. |
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