Eastern Bering Sea

SEA PENS

Taxonomy: Phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Pennatulacea,
family Halipteridae.

Species Representatives: Halipteris willemoesi

Distribution and Life History: Sea pens are colonial corals supported by internal skeletal structures and adapted to living as sessile animals partly imbedded in fine sediments on the sea floor (Barnes, 1980). Spawning may be annual (seasonal) or continual (Eckelbarger et al., 1998). Gametes are released into the water column where fertilization occurs. Planula larvae settle to the bottom after about seven days if favorable substratum is available (Chia and Crawford, 1973). In Puget Sound, the sea pen Ptilosarcus gurneyi is preyed upon by starfish and nudibranchs (Birkeland, 1974). Stands of sea pens provide shelter and food for many organisms including juvenile rockfish (Krieger, 1993). The Family Halipteridae has near cosmopolitan distribution and occurs from 36-1950 m depths (Williams, 1999).

Halipteris willemoesi - Has a patchy distribution in SE Bering Sea, but is commonly taken on outer shelf in the NMFS SE Bering Sea trawl survey. A single pen is a colony of animals. The base of the colony forms a swelling, or peduncle, which anchors the colony to the sea floor. The exposed portion of the colony can reach 1.5 m in height and supports fleshy secondary polyps that cover the hard shaft, or rachis. Feeding polyps capture small animals. Fish eggs were present in one EBS specimen. Examination of the rachis reveals over 100 growth rings that may be annuli. Definitive ageing is currently underway ⁽²⁾.