At first glance, this leopard seal (Hydrurga leptonyx) might seem like it’s having the time of its life—mouth wide open in what looks like a hearty laugh. But don’t be fooled by its seemingly comedic ...

But when they eat penguins, leopard seals are normally highly territorial, scaring off rivals by lunging at them with a fearsome set of teeth. Animal-mounted cameras have even revealed that ...