Interview with Sea Life: Stony Coral

scuba diver on coral reef
By Dani Knod

Behind the tough-guy appearance of the Stony Coral lays a fragile living layer. So delicate, a simple kick with a fin can kill it; this thin blanket of life is responsible for the growth and survival of the entire structure. Consisting of countless tiny organisms, called polyps, the coral uses this outer skin to feed. Tucked away during the day, once the sun goes down, the polyps come out to dine!

By waving and snapping their tentacles, polyps feed on microscopic organisms floating helplessly in the warm tropical sea around the reef. Fine hairs cover the surface of the 6 tentacles, and these hairs work like a comb, sifting the food pieces out of the water passing overhead. These carnivorous tendencies of the polyp provide much of the food a coral needs to survive, but not all.

coral drum
This is where the most versatile trait of the coral comes into save the day. Inside their skin resides a certain type of algae (zooxanthellae). Allowing each polyp to perform photosynthesis, like a plant, this alga helps generate more food for the entire coral. Also, the zooxanthella is what gives coral its color. So, a coral without zooxanthellae is white in color, or has been bleached.

When the polyps are able to receive enough food, they are able to keep the coral healthy and increasing in size. In order to do this, each polyp secretes a cup-shaped calcium skeleton that separates it from the neighboring polyps. It is through decades and centuries of consistent secretion of these cups that the whole reef is built. During your next snorkel or dive take a closer look at the creature that is the backbone to our entire reef system, the stony coral!


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