Video taken at Australia’s Ningaloo Reef shows that whale sharks can hunt baitfish in tandem with other predators. Whale sharks are known to chase fish on their own, but they’re relatively slow swimmers. When speedier animals, such as tuna and diving birds, force prey into a defensive ball, the largest mouth gets the most fish. This behavior, rarely documented, may be a way for the giant sharks to save energy while foraging. —Sarah Keartes

Horse conchs, America’s largest sea snails, are at higher risk of extinction after a century of unregulated harvesting of their shells, a new study finds. Using chemical isotopes from conch shells to gauge age and reproductive maturity, scientists found