Species: Sphyrna zygaena, Smooth Hammerhead, Smooth Hammerhead Shark

Sphyrna zygaena (Linnaeus, 1758)

Smooth Hammerhead, Smooth Hammerhead Shark

A hammerhead shark with broad, narrow-blade lateral extensions on the head; width of hammer 26-29% of TL; front margin of head broadly convex, with prominent side indentations, but no central indentation; teeth similar in both jaws, oblique, deeply notched on rear side, weakly serrate in adults, rear teeth like front teeth; nostrils short, before eyes on head plane; five gill slits, last one over pectoral; 2 dorsal fins, first moderately large and erect, its rear margin concave, its free rear tip not reaching above level of pelvics; origin of second dorsal fin slightly behind origin of anal fin; free rear tip of 2nd dorsal ends well before tail fin base; second dorsal and pelvic fins low, rear edge of pelvic ~ straight; anal fin with rear margin prominently notched; transverse pit above tail base crescent shaped, a pit below tail base; tail fin strongly asymmetrical, notched under tip of top lobe, large lower lobe.

Dark olive to dark grey-brown on back and sides, white below; undersides of pectoral fin tips dusky.

Grows to 400 cm; reaches 25 y.

A coastal-pelagic and semi-oceanic hammerhead often sighted near the surface.

Depth: 0-200 m.

Circumglobal in tropical and temperate seas; Canada to Argentina.