 In a 2007 ribosomal DNA study, the spinner shark was found to be the most genetically divergent of all the requiem shark species examined save for the tiger shark ("Galeocerdo cuvier"), being less related to other "Carcharhinus" species than the lemon shark ("Negaprion brevirostris").Some uncertainty exists in the distribution data for the spinner shark due to confusion with the blacktip shark.In the Western Atlantic Ocean, it occurs from North Carolina to the northern Gulf of Mexico, including the Bahamas and Cuba, and from southern Brazil to Argentina.