(CNN)Although sea turtles have been chomping down on plastic bags for years, scientists didn't know why -- until now. Plastic bags may smell like a tasty treat because of the bacteria and algae that accumulate on them.
Plastic bags may smell like food to hungry sea turtles, a new study says
In a new study published on Monday in the journal Current Biology, scientists presented captive sea turtles with multiple different smells.
The turtles responded almost identically to the smell of their food as they did to the smell of a plastic bag that had been soaked in water, according to Matthew Savoca, a postdoctoral research fellow at Stanford University's Hopkins Marine Station and one of the study's authors.
In fact, the turtles kept their noses out of the water three times as long to smell the plastic bags compared to control smells.
Nick Mallos, senior director of Ocean Conservancy's Trash Free Seas program, says this study provides alarming new information about why turtles eat plastic.
Until now, there were just theories that sea turtles may have accidentally gotten entangled in the plastic, or perhaps they mistook plastic bags for juicy jellyfish.
''What's very concerning about this research is that it suggests that sea turtles are proactively seeking out plastics because of the smell," says Mallos, who was not involved in the study.
Savoca agrees that the problem is more complex than a simple mistake by curious sea creatures.
"I've heard numerous times that animals just eat plastic because they don't know any better," says Savoca. "What this type of research shows is that there are really complex evolutionary mechanisms that govern how animals are finding food."
He theorizes that turtles have evolved to pursue certain smells that signal food, and therefore instinctively move towards the smell of the algae and bacteria when they accumulate on plastic in the ocean.