Scalloped hammerhead shark

Photo: Kris Mikael Krister · CC BY

Scalloped hammerheads aggregate in cooler upwelled water off Niihau's western face, gathering in loose schools during the day before dispersing to hunt at night. Their wide-set eyes and hammer-shaped cephalofoil provide a nearly 360-degree visual field and amplify electroreception, making them highly efficient predators of fish and cephalopods. Critically endangered globally due to shark fin trade, their numbers at Niihau are one of the last reliable viewing populations within US waters and reflect the site's exceptional protection status.