Most of the world’s shark species have five gill slits; aptly named sixgills have six slits along the sides of their heads and are considered more primitive. Sixgills have been around since before dinosaurs roamed the earth. With their six gill slits and dimorphic teeth — which means the top teeth are different from the bottom — they bear a close resemblance to extinct shark species.
Big bodies, big appetites
Sixgills are the world’s third-largest predatory sharks; they’re comparable in size to great white sharks. Like great whites, sixgills are at the top of their food chain. Their prey includes dogfish, skates and bony fishes. In studies done off the coast of South Africa, sixgills were found to have seals and other marine mammals in their stomachs.
Increasing our knowledge: sixgill research at the Seattle Aquarium
Sixgill sharks are elusive. They generally remain at deep depths and stay away from light. But, thanks the unique opportunity offered by their presence at shallow depths in Puget Sound—and even right under the Aquarium’s pier on Elliott Bay—we were able to study and learn more about our local population of sixgills through a research program that began in 2002 and was suspended in 2016. Through our research, we attempted to answer some questions about sixgill population dynamics, home range, breeding patterns and relationships with sixgill populations worldwide. For more information, visit our sixgill shark research page.