Spinner Sharks can be differentiated from other sharks without an interdorsal ridge by the black tips on its fins. Spinner sharks have an additional black tip on its anal fin. Atlantic Black Tip Sharks also have black tips on fin, but its anal fin will be white, with no black tip. Bull sharks have black tipped fins, and black-tipped anal fins, but its snout is blunt and rounded (shorter than the mouth is wide). Spinner sharks insertion of the first dorsal fin is well behind the back of the pectoral fin.