Scalloped hammerhead shark

Photo: Kris Mikael Krister · CC BY

Scalloped hammerheads use the channel between the Bookends pinnacles as a seasonal aggregation point, with the current-swept passage offering schooling prey fish. The distinctive cephalofoil head houses an exceptionally wide-set electrosensory system, allowing hammerheads to detect the bioelectric fields of buried prey in sandy substrate. Listed as critically endangered, encounters at Bookends represent a significant conservation value, as aggregation sites are the first to be lost when shark populations are reduced by fishing.