There are six sharpnose sharks in the Rhizoprionodon genus of the requiem shark family, all sharing a similar external appearance that is characterized by a long, flattened snout.
The best-known member of the family is the Atlantic sharpnose (R. terraenovae), which is a very popular small species as an inshore food fish and a small gamefish in the Gulf of Mexico. It grows to between 2 and 4 feet in length and has the characteristic long and flattened snout, as well as a slender brown to olive-gray body with a pale belly. The dorsal and the caudal fins may be edged in black, especially in the young, and often there are small, scattered whitish spots on the sides.
The Atlantic sharpnose is further distinguished by well-developed furrows in the lips at the corners of the mouth and by the second dorsal fin, which begins over the middle of the anal fin. This sharpnose ranges as far north as New Brunswick but is rarely found north of North Carolina. The Caribbean sharpnose (R. porosus) may actually be a subspecies of the Atlantic sharpnose but is found mostly in Caribbean waters.
The Pacific sharpnose (P. longurio)is fairly common in the Gulf of California and a frequent catch of the shark fisheries there, extending as far south as Peru.