A joint study between the University of Hawaii - Manoa and the University of Tokyo reveals that two species of sharks have positive buoyancy. Nathan Frandino reports.
Meet the sixgill shark. This deep-sea member of the cow sharks order has scientists at the University of Hawaii at Manoa and the University of Tokyo scratching their heads. Why? Because they've learned that the sixgill has positive buoyancy, making it a difficult dive to deeper depths. After fitting the shark with an accelerometer data logger, the researchers tracked its swim speed, navigation, and body orientation. Most sharks are negatively or neutrally buoyant and will sink if they stop swimming. But the sixgill must exert itself more to swim downhill. It can also stop swimming and simply glide when going uphill. Scientists found similar traits with the prickly shark, which also makes its home deep under the sea. Now that researchers know the sharks are positively buoyant, they next hope to find out why.