B-11 



and Lydonia Canyons. 



GORGONACEANS 



PavagoTgia avhorea (Linnaeus) 



Alayonium arboreum^ Linnaeus, 1758 



Paragorgia arborea^ Milne, Edwards and Haine, 1857 



Paragorgia arborea, Verrill, 1922:17 



Paragorgia arborea^ Deichmann, 1936:81 



Paragorgia arborea is the largest gorgonian found along the 



northeast coast. Colonies can be 1.5 m or more in height and 



have a basal diameter of 10 cm or more. The branches, which tend 



to lie in a single plane, are thick, rigid and often have nodes 



or swellings along their length and especially at their free end. 



As a scleraxonian gorgonian, P, arborea lacks a central axis of 



gorgonin and instead the central core of the stem and branches is 



densely packed with calcareous spicules. The spicules are in the 



shape of irregularly warted or tuberculated rods and spindles. 



In contrast the spicules of the coenechymal tissue are largely 



small capstans - short blunt-ended rods with two whorls of knobby 



tubercles along their length. The polyps of P. arborea are 



dimorphic in that they consist of large autozooids and minute 



tentacleless siphonozooids. Both types are scattered irregularly 



on the branches - although sometimes more crowded on one side. 



The autozooids are retractible into low dome-shaped calyces. 



The eight-lobed margin of the calyces folds over the retracted 



polyps forming a star-shaped operculiom. The living colonies 



