A small hammerhead shark with a very narrow, rounded shovel-shaped head, without the prominent lateral-blade extensions of other hammerheads; width of head 18-25% (usually < 21%) of TL; front margin of head broadly convex and without indentations; length before mouth about 40% of head width; front teeth blade-like, with 1 short, stout point, lower teeth straight, upper teeth oblique, deeply notched on rear side; enlarged keeled molariform teeth at back of jaws; first dorsal fin moderately large and erect, its rear margin concave; second dorsal fin base about half length of anal fin base; origin of second dorsal fin above middle of anal fin; anal fin rear edge shallowly concave; 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.
Grey or grey brown on back and sides, whitish below; often small dark spots on back.
Maximum size about 150 cm, 10.8kg; size at birth 35-40 cm.
A common inshore hammerhead ranging into shallow estuaries.
From the intertidal zone to at least 80 m depth.
Western Atlantic and eastern Pacific (Southern California to Peru, Cocos and the Revillagigedos Islands.