Spurdog


Squalus is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of Squalus would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that Squalus is quite capable of protruding its upper jaw during feeding.
The name comes from squalus, the Latin for shark; this word is the root for numerous words related to sharks such as squaline and scientific names for sharks, such as the order Squaliformes.

Species

Currently, 33 recognized species are placed in this genus:Squalus acanthias Linnaeus, 1758 Squalus albicaudus Viana, M. R. de Carvalho & U. L. Gomes, 2016 Squalus albifrons Last, W. T. White & J. D. Stevens, 2007 Squalus altipinnis Last, W. T. White & J. D. Stevens, 2007 Squalus bahiensis Viana, M. R. de Carvalho & U. L. Gomes, 2016 Squalus blainville Squalus brevirostris S. Tanaka (I), 1917 Squalus bucephalus Last, Séret & Pogonoski, 2007 Squalus chloroculus Last, W. T. White & Motomura, 2007 Squalus clarkae Pfleger, Grubbs, Cotton & Daly-Engel, 2018 Squalus crassispinus Last, M. J. Edmunds & Yearsley, 2007 Squalus cubensis Howell-Rivero, 1936 Squalus edmundsi W. T. White, Last & J. D. Stevens, 2007 Squalus formosus W. T. White & Iglésias, 2011 Squalus grahami W. T. White, Last & J. D. Stevens, 2007 Squalus griffini Phillipps, 1931 Squalus hawaiiensis Daly-Engel, Koch, Anderson, Cotton, Grubbs, 2018 Squalus hemipinnis W. T. White, Last & Yearsley, 2007 Squalus hima Swetha, Bineesh, Beira, Das, & Bhaskar, 2024 Squalus japonicus Ishikawa, 1908 Squalus lalannei Baranes, 2003 Squalus lobularis Viana, M. R. de Carvalho & U. L. Gomes, 2016 Squalus megalops Squalus melanurus Fourmanoir & Rivaton, 1979 Squalus mitsukurii D. S. Jordan & Snyder, 1903 Squalus montalbani Whitley, 1931 Squalus nasutus Last, L. J. Marshall & W. T. White, 2007 Squalus notocaudatus Last, W. T. White & J. D. Stevens, 2007 Squalus quasimodo Viana, M. R. de Carvalho & U. L. Gomes, 2016 Squalus rancureli Fourmanoir & Rivaton, 1979 Squalus raoulensis Duffy & Last, 2007