What are cold-water corals?
There are several types of cold-water coral but they all belong to a group of animals called the Cnidaria. They are closely related to sea anemones, and like sea anemones they live fixed in place and feed by catching prey with their stinging tentacles. Corals are composed of polyps each having a ring of tractable tentacles surrounding a mouth.
As corals cannot move, they extend their sticky tentacles into the water column, hoping to grab a potential meal from the water currents. Corals can use a wide variety of food, including dissolved organic matter and the tiny animals and plants that live in the ocean currents (the plankton).
Some species of coral live as individuals forming a single polyp, while others are colonial which form colonies of many hundreds or thousands of polyps. Colonial corals build large, complex skeletons, usually from calcuim carbonate (limestone). Some species can eventually produce elaborate branching frameworks which over time can grow to become the basis of cold-water coral reefs.
Reef-building corals are very important in the deep-sea environment as they create and modify the surrounding habitat, producing many more places for other animals to live and hide. This in turn increases the abundance and diversity of animal life on the reef, making cold-water coral reefs biodiversity hot-spots in the deep-ocean