The Smooth Hammerhead (Sphyrna zygaena) is part of the family Sphyrnidae. It is named because its cephalophoil does not have an indentation in the middle of the front margin.
Unlike other Hammerhead sharks, the Smooth Hammerhead shark prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks form schools in the hundreds to thousands and migrate towards the poles following cool water.
Family: Sphyrnidae
Genus: Sphyrna
Species: zygaena
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Ground Sharks
Family– Sphyrnidae
Common Name– Hammerhead Sharks
Genus– Sphyrna
Species– zygaena
Status: IUCN Red List VULNERABLE
Average Size and Length: Second largest hammerhead. The average size of the Smooth Hammerhead ranges between 8-12 feet in length with a maximum recorded total length of 16 feet.
Average Weight: The maximum recorded weight is 880 pounds.
Teeth and Jaw: There are 26–32 tooth rows in the upper jaw and 25–30 tooth rows in the lower jaw. Each tooth is triangular, with smooth to weakly serrated edges.
Head: The Smooth Hammerhead cephalophoil is wide and smooth, slightly arched and scalloped, with a distinct notch at the ends near the eyes. The nostrils are located near the ends of the cephalofoil, with long grooves running towards the center.
Dermal Denticles: They are close together, each with 5–7 horizontal ridges (3 in juveniles) leading to a W-shaped rear margin.
Demographic, Distribution, Habitat, Environment and Range: The Smooth Hammerhead is a coastal shark that prefers shallow waters, sometimes even observed upriver in freshwater. It prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes forming schools numbering in the hundreds to thousands (juvenile).
Diet: Most of its diet is smaller sharks and rays, and some bony fish and invertebrates.
Aesthetic Identification: The Smooth Hammerhead has a classic shark-shaped body with a taller dorsal fin, and is usually a dark olive brown, fading to ivory to white underneath. The body is streamlined, without a dorsal ridge between the two dorsal fins. The first dorsal fin is moderately tall and falcate in shape, with a rounded tip. The pectoral and pelvic fins are not falcate, rather having nearly straight rear margins. The anal fin is larger than the second dorsal fin, with long free rear tip and a strong notch in the rear margin. Sometimes the pectoral fins have dark edges underneath.
Biology and Reproduction: The Smooth Hammerhead is viviparous and gives birth to litters of 20–40 pups.
Behavioral Traits, Sensing and Intelligence: Smooth Hammerhead sharks may come together in great numbers during their annual migrations; schools of over a hundred juveniles under 4.9 ft long have been observed off the eastern Cape of South Africa, and schools thousands strong have been reported off the coast of California. The schools and migrates with the seasons.
Speed: unknown
Smooth Hammerhead Future and Conservation: Smooth Hammerheads are caught by commercial fisheries throughout the world, including those off the United States (East and West Coasts), Brazil, Spain, Taiwan, the Philippines, southwestern Australia, and western Africa, primarily using gillnets and longlines. Fishery catches of Smooth Hammerheads are difficult to quantify due to a frequent lack of distinction between them and other large hammerheads. The meat is sold fresh, dried and salted, or smoked, though in most markets it is considered undesirable and there are reports of poisoning. The fins are most valuable, which have the highest rating for use in shark fin soup and often leads to captured sharks being finned at sea. The liver oil is used for vitamins, the skin for leather, and the offal for fishmeal. This shark is also used in Chinese medicine.
Smooth Hammerhead Recorded Attacks on Humans: Potentially dangerous.