Bigelow & Schroeder, 1950
The shortail skate (Amblyraja jenseni) (Alexei Orlov) is a poorly know species of fish discovered in 2004 during a study of bottom ichthyofaunal aboard the Norwegian R.V. “G.O. Sars”, where four species were identified, including Amblyraja jensieni.
Amblyraja jenseni is a member of family Rajidae, of which 30 genera and over 180 species are recognized. Amblyrija is the genus name of which 10 species are recognized, including Amblyraja doellojuradoi (southern thorny skate), Amblyraja frerichsi (thickbody skate), Amblyraja robertsi (bigmouth skate), etc. (M. Coulson).
Members of the family Rajidae carry uncharacteristically similar body plans. This makes visual identification of these individuals extremely difficult. Detailed visual descriptions of Amblyraja jenseni are hard pressed to come by, so the description below may represent several of the family Rajidae and should not necessarily be used to differentiate them. Amblyraja jenseni is a medium size skate. Its maximum known length is 74.3 centimetres (29.3 in) for males and 85 centimeters (33 in) for females (Orlov). The coloration is chocolate-brown to gray-brown above with scattered darker spots. Below the body appears a patchy white and brown mixture, except for the pelvic fin lobes and tail, which are darker. These white patches are on the snout, upper abdomen, nostrils, mouth gill slits, and anal opening. Its underside is smooth and its dorsal surface is densely covered with prickly scales (). There are 2 - 3 pairs of distinctive scapular thorns on each shoulder, usually arranged in a triangle, and a row of 24-29 median thorns along the back, flanked by a row of smaller lateral thorns on the tail. The tail of the Jensen’s skate is relatively short (Orlov). Sexual dimorphism in Jensen’s skates is present in pelvic fin structure that the males modify to act as copulatory claspers, as well as alternate disc lengths, horizontal diameter of the orbit, height of the tail at the pelvic fin tips, length of the third gill slit, and distances from the center of the anus to the first and second dorsal fins (Orlov).
Distribution and Habitat
This species of skate is believed to only be found in the North Atlantic, off the coasts of New England, Nova Scotia, Grand Banks of Newfoundland, Iceland, Ireland, Canada, and also along the Mid Atlantic ridge at depth of 167-2,548 meters (548 to 8,360 ft) (Orlov). Making it one of the deepest-occurring skates known.
Biology and Ecology
Skates represent a critical consumer of invertebrate and cephalopods, and small fish, representing a similar role as apex predators of the ecosystem. Little is documented about Amblyraja jenseni’s feeding behavior, but it is presumed that like other of its family, it would eat various cephalopods, crustaceans, and small bony fish such as rattails and teleost fishers (Orlov). Amblyraja jenseni is presumed to be oviparous like other skates but no record of observed reproduction cycles is at hand (Orlov).
- Coulson, M. W., et al. “DNA Barcoding of Canadas Skates.” Molecular Ecology Resources, vol. 11, no. 6, Sept. 2011, pp. 968–978. Wiley Online Library, doi:10.1111/j.1755-0998.2011.03034.x.
- Orlov, Alexei M., and Charles F. Cotton. “Sexually Dimorphic Morphological Characters in Five North Atlantic Deepwater Skates (Chondrichthyes: Rajiformes).” Journal of Marine Biology, vol. 2011, 2011, pp. 1–18., doi:10.1155/2011/842821.
- Orlov, Alexie M, et al. “Deepwater Skates (Rajidae) Collected during the 2004 Cruises of R.V. ‘G.O. Sars’ and ‘M.S. Loran’ in the Mid-Atlantic Ridge Area.” ResearchGate, Jan. 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2011). "Amblyraja jenseni" in FishBase. February 2011 version.
- "http://www.iucnredlist.org/apps/redlist/details/161491". Retrieved 11 March 2011. External link in