Eastern Bering Sea

HORNY CORALS

Taxonomy: Phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Gorgonacea

Species Representatives: Paragorgia arborea, Primnoa willeyi

Distribution and Life History: Hard corals belong to several diverse orders within the Phylum Cnidaria (Barnes, 1980). The horny, or fan corals are members of the Order Gorgonacea and comprise all of the corals (with the exception of the soft coral Gersemia) that have been identified on the NMFS SE Bering Sea survey. Horny corals are rare near the edge of the SE Bering Sea shelf and slope. In the majority of horny corals, growth resembles that of a plant, with a short main trunk fastened to the substrate, and lateral branching stems which may be in the same plane. The living tissues are composed of polyps, each with a mouth surrounded by tentacles. Some species are composed of a single polyp while others are colonies of many polyps. (Cimberg et al., 1981). Fertilized eggs develop within the female polyps into planula larvae. Planula larvae of most corals are not usually dispersed very far from parent colonies. In colonial species, asexual reproduction also occurs through budding of the primary polyp. Growth of most corals is slow and they may require over 100 years to reach maximum size (Cimberg et al., 1981). Horny corals are suspension feeders, taking their food from the water column. Coral predators include snails, fish, polychaetes, sea stars, and nudibranchs (Cimberg et al., 1981).

Paragorgia arborea (Kamchatka coral) - Uncommon north of the Alaska Peninsula (Kessler, 1985). Ranges from the Bering Sea and Aleutian Islands to California in depths of from 200-2000 m. Forms a large colony, branching on many planes. Height to more than 2 m ⁽¹⁾.

Primnoa willeyi (red tree) - Rare north of the Alaska Peninsula (Kessler, 1985). The genus Primnoa has been found at depths of from 10 - 800 m, with concentrations between 50 and 250 m. Probably lives for over 100 years (Cimberg et al., 1981).