Sea Otters Could Crack Nuts With Their Teeth Like Ancient Humans

Super strong chompers, more than twice as tough as ours, let sea otters crunch through the shells of crabs and clams, scientists report in the journal Biology Letters.

Biologists and archaeologists from Kuwait, Germany and the United States examined the Hunter-Schreger bands, the enamel structure that prevents chips in teeth. Compared with humans, otters' bands were more common, making the teeth less prone to chipping. In fact, the bands in the otters' pearly whites resembled the teeth of an early human ancestor who subsided on nuts and hard fruit.

It's tough to get a sense of exactly what our ancestors ate - but looking at chips and wear on fossilized molars of Paranthropus boisei, a hominin found in eastern Africa, indicates they consumed small, solid items. Because otter teeth are easier to examine than fossilized molars - and we know the otter diet contains lots of hard items - the archeologists could use the marine mammals as toothy stand-ins for long-lost apes.

Sea otter teeth do much more than a good paleo impression, of course. By eating tough sea creatures, otters play an important role in their ecosystem. (They've got quite a healthy appetite: Due to a high metabolic churn - otters don't have blubber - they have to eat a quarter of their body weight daily.) In the North Pacific, hungry otters act as keepers of the kelp forests. But when otter populations dip, as what happened after the Exxon Valdez oil spill in 1989, their prey populations quickly expand. Without otters, unchecked numbers of sea urchins chow down on kelp "like flies on honey," which creates an imbalanced ecosystem, the National Oceanic and Atmospheric Administration writes.

Conserving the four-foot-long animals - who are listed as threatened under the Endangered Species Act - is vital. Researchers are studying the impact of boats, fishing gear and pollutants in their habitats with the goal of increasing the sea otter population.