322 Shark and Company 





A Smooth dogfish ( Mustelus canis ) . 



Courtesy, Harvard Museum of Comparative Zoology 



mum length, 5 feet), and its abundance— all are attractions which make 

 it a popular specimen for laboratory study in zoology and biology class- 

 rooms. For this reason, large numbers are caught each year and preserved, 

 making this slender, graceful little shark a species which has been in- 

 tently studied for years. 



Like the Spiny dogfish, the Smooth dogfish is sensitive to temperature 

 changes, and its migrations seem to be governed somewhat by water 

 temperature. These Dogfish winter between the southern half of North 

 CaroHna and the offing of Chesapeake Bay. A sudden chill in these win- 

 ter waters will occasionally kill Smooth dogfish. Their summer visit 

 along the coast from Delaware to Cape Cod ends abruptly, and they 

 withdraw almost simultaneously from all points on the coast when the 

 water cools. 



The Smooth dogfish stays fairly close to shore and is normally found 

 in waters of less than 10 fathoms (60 feet). It is aided in its bottom- 

 search for lobsters and crabs by its ability to change its color shading 

 to blend with the background, to an extent unusual for sharks. Its range 

 of color change spans tints from pearl to dark gray. 



Mustelus canis itself ranges from Cape Cod, and occasionally the 

 Bay of Fundy, southward to Brazil and Uruguay in the western Atlantic. 

 It is well known along the coasts of Great Britain, where it is called the 

 Smooth Hound. It is found in the Gulf of Mexico and has been reported 

 in the Calcasieu River of Louisiana, as far inland as Prien Lake. In South 

 African waters, it is known as the Hound. (Apparently, they earned 

 their canine common names from their habit of traveling in packs, or, 

 to be piscatorial, schools.) A species similar to M. canis {Mustelus nor- 

 risi Springer, 1939) is found in the Florida Keys and off the west coast 

 of southern Florida. Two species (M. rmistelus Linnaeus, 1758, and 

 M. asterias Cloquet, 1819) are known in the Mediterranean and the eastern 

 Atlantic. 



Along the North American Pacific coast, three Smoothhounds are 

 known: the Gray, the Sicklefin, and the Brown. 



