Smooth Hammerhead

Smooth Hammerhead (Sphyrna zygaena) Fish Description

Also known as round-headed hammerhead, common hammerhead, and common smooth hammerhead, the Smooth Hammerhead is a member of the Sphyrnidae or hammerhead shark family. The name of this species was inspired by its remarkable hammer-shaped head absent an indentation in the center of the front margin (hence “smooth”). Its fins are highly prized as an ingredient in shark fin soup.

What makes the Smooth Hammerhead distinct from other members of the Sphyrnidae family is how its head is curved, and wide but short. Its nostrils are near the ends of its curved head. The Smooth Hammerhead, which is an active predator, has 25 to 30 tooth rows in the lower jaw, and 26 to 32 tooth rows in the upper jaw. Each of its teeth has serrated edges and is triangular in shape.

Diet and Size

Smooth Hammerheads feed on fellow sharks and rays. They are active predators, preying on invertebrates and bony fishes. They also like feasting on octopus, squid, hake, dolphins, and sea snakes, among others.

The Smooth Hammerhead is the second-largest member of the hammerhead sharks, ranking next to the great hammerhead shark. On average, it can measure up to 138 inches or 11.5feet long.

Interesting Facts About the Smooth Hammerhead 

• The laterally extended and flattened head of the Smooth Hammerhead (and its cousin hammerheads') is called a “cephalofoil”.
• Smooth Hammerheads form schools consisting of hundreds to thousands during their migration.
• Like other members of its family, the Smooth Hammerhead is viviparous, giving birth to around 20-40 baby sharks.
• Smooth Hammerheads have been reported to have attacked humans before; they are potentially dangerous.
• The Smooth Hammerhead uses its electroreceptors (ability to detect electric fields made by other fishes) to locate its prey more accurately.
• Every year, around 1.3 to 1.7 million fins are harvested for the shark fin trade from the Smooth Hammerhead.

Smooth Hammerhead — Fishing Techniques

Compared to other sharks, the Smooth Hammerhead is quite common; thus, it is prone to intentional fishing especially by commercial fishers. Sometimes, the Smooth Hammerhead is also captured as bycatch especially when anglers use purse-seines, bottom trawls, handlines, gillnets,  and longlines.

Habitat and Distribution

Smooth Hammerheads — unlike other hammerheads — prefer temperate zones with temperatures ranging from 45.5 °F to 81.5 °F. They are abundant, especially in higher latitudes. They can be found in the Atlantic, and in Northern Europe. Specifically, the Smooth Hammerheads are aplenty in the waters of Nova Scotia to the Virgin Islands, Brazil to Argentina, and from the British Isles to the Mediterranean Sea. This shark species is also sighted in the Indian Ocean, particularly in India, Sri Lanka, and South Africa. It also occurs in southern Japan, Russia, New Zealand, and Australia.

This hammerhead shark likes inshore waters like estuaries and bays, but it is also found around oceanic islands and in the open ocean. Unlike the great and the scalloped hammerheads, Smooth Hammerheads thrive in waters closer to the surface (less than 66 feet). However, they can also be found in waters as deep as 660 feet. 

During the summer months, the Smooth Hammerheads move to the cooler poles, then return to the equator during winter.