%0 Journal Article
%T Sexually Dimorphic Morphological Characters in Five North Atlantic Deepwater Skates (Chondrichthyes: Rajiformes)
%A Alexei M. Orlov
%A Charles F. Cotton
%J Journal of Marine Biology
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/842821
%X Skates exhibit a variety of manifestations of sexual dimorphism. However, this phenomenon has been poorly documented in deepwater species. New data on the sexual dimorphism of five species of deepwater skates from the North Atlantic Ocean are presented: Amblyraja jenseni, Bathyraja pallida, Bathyraja richardsoni, Rajella bigelowi, and R. kukujevi. These skates exhibit sexual dimorphism most frequently in interorbital width, disc length and width, length of the third gill slit, horizontal diameter of the orbit, length of the fifth gill slit, space between the first and fifth gill slits, length of the second dorsal fin base, mouth width, length and width of each lobe of the nasal curtain, distance from the snout to the center of anus, distance from the snout tip to the point of maximum disc width, length of the lateral fold, length of the orbit + spiracle (measured together), tail height at the pelvic fin tips, and the number of median thorns. 1. Introduction Skates (Rajoidei) comprise an important component of shelf and continental slope benthic communities of the world¡¯s oceans. They are major consumers of cephalopods, decapods, and fishes, often utilizing the same food resources as the apex predators, such as sea birds, marine mammals, and sharks [1]. Skates, like all chondrichthyan fishes, exhibit sexual dimorphism in the structure of the pelvic fins, which in males are modified to act as copulatory organs, or claspers [2]. Also, mature male skates have alar thorns on the edges of the disc, which help to grasp the female during copulation [3¨C5]. In many species sexual differences have been reported in length, body mass, size and age of sexual maturity, other external morphological features, and diet [3, 5¨C16]. Mature females and males of several skate species exhibit differences in the form and length of the teeth [3, 15, 17¨C23]. In one species, differences were observed in the shape and size of the shoulder and pelvic girdle [24]. Sexual differences in size and shape of the olfactory and electrical organs have also been found in some skates [3, 25¨C27]. Even with this variety of manifestations of sexual dimorphism in skates, the phenomenon has been poorly documented in deepwater species. This study presents new data on sexually dimorphic morphological characters of five deepwater skate species from the North Atlantic Ocean: Jensen's skate, Amblyraja jenseni [28]; pale ray, Bathyraja pallida [29]; Richardson's ray, Bathyraja richardsoni [30]; Bigelow's ray, Rajella bigelowi [31]; Mid-Atlantic skate, R. kukujevi [32]. 2. Materials and Methods Our
%U http://www.hindawi.com/journals/jmb/2011/842821/