All species of requiem sharks have a head of normal shape. Their eyes have a nictitating (winking) membranes. They have caudal fins with the upper lobe being larger than the lower but not very long, two 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. 