All species of requiem sharks have a head of normal shape, eyes with a nictitating (winking) membranes, caudal fins with the upper lobe being quite larger than the lower but not very long, 2 spineless dorsal fins, the first one usually much larger than the second in most of the Atlantic species, an anal fin, a caudal peduncle which doesn't have lateral keels, and sharp, bladelike teeth with a single cusp. 