Cnidarians

Cnidarian animals have varied body forms, living as single polyps or as complex colonies, but with a single suspected evolutionary origin. All cnidarians produce small intercellular stinging capsules, called cnidae.

Corals

There are ten species of anthozoan corals confirmed present in the NWT section of the western Arctic Ocean. The Anthozoans (Class Anthozoa) included in the NWT General Status Ranks are members of the phylum Cnidaria. Other cnidarians not included in the list are the hydrazoans (e.g., hydras and Portuguese man o’ war), the scyphozoans (true jellyfishes), and the cubozoans (box jellyfishes). These species groups will be included in the future.

The best known anthozoans are the reef forming corals, or stony corals (in subclass Hexacorallia). Formation of reef systems begins as one polyp (a body form of some cnidarians) secures to a structure and reproduces. A new polyp joins the first and so on until a large interconnected system of polyps develops. In reef forming corals, polyps have a small limestone skeleton located at the base of their bodies. This structure remains after a polyp dies and acts as a surface for new polyps to build from. Polyps can build and stack in this fashion for thousands of years, eventually constructing massive systems such as the Great Barrier Reef in Australia.

Like stony corals, the sea anemones (Order Actiniaria in subclass Hexacorallia) are formed of polyps. However, these organisms tend to be solitary and much larger. Their anatomy consists of a sac like structure firmly attached to the ocean substrate or other structure. The mouth is located at the top of the organism and is surrounded by one or more whorls of tentacles that help grasp and draw in food.

Tube-dwelling anemones are very similar in appearance to sea anemones, but are in fact a separate and distinct subclass (Ceriantharia). As their common name describes, these organisms live in a tube structure made from a fibrous secretion. They are able to draw themselves into these tubes for protection.

The soft corals (subclass Octocorallia) known to be present in the NWT waters of the Western Arctic Ocean, including the Beaufort Sea, have a wide variety of structures and appearances but do not form large reefs.