The smooth hammerhead, Sphyrna zygaena, is a large hammerhead shark living in temperate and tropical seas. It is differentiated from other species of hammerhead by the smooth shape of its cephalophoil (head) and its lack of a central indentation. Its coloration varies from brownish-gray to deep olive (as with most hammerhead sharks), fading to a pale whitish color on its underside. The shark's teeth are similar on both the upper and lower jaws, are triangular and smooth edged. Adults of the smooth species attain lengths up to 4 meters, and can weigh more than 400 kilograms.
The smooth hammerhead shark is the only species of hammerhead that appears in Canadian coastal waters, having been reported off the coast of Nova Scotia, Canada near Herring Cove, Sambro Light, Brier Island, and St. Margarets Bay.
This hammerhead is a viviparous species that gives birth to a comparatively large litter, between 20 to 40 pups. The pups are approximately 50 centimeters long at birth. Individuals become sexually mature at about 2.3 meters in length.
While the smooth hammerhead can be found world-wide, they occur primarily in warm-temperate waters, and rarely in very warm or tropical water. They prefer waters relatively close to shore where the water is less than 20 meters in depth, though they can be found in very large schools (more than 100 individuals) during migration to cooler latitudes during warmer seasons.