|First Alaska Explorations | Recent Work
The seas surrounding the Aleutian Island
chain may harbor the highest abundance and diversity of coldwater corals
in the world. Unlike tropical corals, these high-latitude corals do not
form reefs but, rather, assemble into dense gardens, and some are thought
to live hundreds of years. Scientists have known something of Alaska's
corals for nearly a century; they turned up in trawls in the first expeditions
here. But, because of the region's remoteness, they have been little explored
by science - until recently.
These polyps are typically joined together in groups, known as "colonies," of hundreds or thousands at a time, by tissue. The connected polyps sit on or surround a skeleton, made by a secretion that hardens into a bone-like structure.
If you've ever found a piece of bleached-out white "coral" on a beach or seen it at a gift shop, this is not a living coral, but a coral "skeleton," stripped of its fleshy polyps. In the ocean on a living specimen, however, the polyps are easy to see. Some people think they look like tiny anemones or jellyfish sitting on their heads and spreading out miniature tentacles into the current to capture food particles.
What makes Alaska's deep-sea corals different?
Alaska corals do not form reefs like tropical corals, in the true sense, but rather form extensive gardens in the Aleutian Islands.
What kinds of corals are in Alaska?
Alaska's corals generally fall into several major groups, including cup corals, octocorals, hydrocorals and black corals:
Cup Corals (Scleractinians):
The sea fans (Gorgonians), a branching type of octocoral, are so far the most common known in the Aleutian Islands. These include gorgonians such as bamboo corals, whose skeletons are segmented to give the appearance of bamboo, and tree corals, which look more like branches. One type of "red tree coral, has been found growing up to 5 meters high and 7 meters wide. Some are thought to live hundreds of years. The oldest verified was found to be more than 800 years old, making it likely that some may live to be more than a thousand. Other octocorals include stolon corals, an encrusting type of coral (Stoloniferan).
Black corals (Antipatharia):
This Alaska coral is commonly called a "bubblegum coral." Scientists know it as a gorgonian coral called a Paragorgia, a branching type of octocoral.
Credit: Bob Stone / NOAA Research.
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