Most wraps like paper or plastic smell like something. If it’s a McDonald’ wrapper, it smells like McDonald’s.
Biologists have long wondered why sea critters eat floating plastic. They used to believe it was because plastic floating in the ocean looked like food.
But there’s now new research that suggests that for a lot of seabirds, plastic actually smells like food. It’s all due to a common algae called zooplankton floating in the ocean much munched on by tiny animals such as krill.
The algae once it’s eaten by animals like krill emit a chemical called dimethyl sulfide.
Biologist Matthew Savoca told NPR that it’s more than a smell, dimethyl sulfide stinks up the place. It’s actually a chemical scream.
The algae are sort of crying out, saying ‘Oh my gosh, we’re being eaten and can someone please help me.’ “
That might sound ridiculous but, in fact, help does come — in the form of birds. When seabirds like shearwaters smell that chemical, they know it means tasty krill are in the water.
“Think of it as like a dinner bell,” Savoca says. “So if we heard a dinner bell ringing, the dinner bell would signify where we could find food. “
Savoca and his team at the University of California, Davis, wondered if birds were accidentally eating plastic because there was stinky algae living on it. So they put plastic out to float around in the ocean.
Then they took it to the university’s food and wine laboratories — this is Northern California, after all. They got some weird looks when they stuffed plastic into equipment designed to track chemicals in fine wine. But they did get their answer.
“Sure enough,” Savoca says, “all this plastic reeked of that sulfur compound, likely due to the algae that coated it when it was out at sea.”
Marine ecologist Chelsea Rochman at the University of Toronto says that, obviously, eating plastic isn’t good for the birds — it’s made with some harmful chemicals that aren’t meant to be eaten. But the plastic also picks up other chemicals in the ocean that make it even nastier.
“Plastic is a sponge for a lot of the chemicals that are in oil and the chemicals that are washing off from different sources, like pesticides and flame retardants and other industrial pollutants,” Rochman says.
Together, these results suggest that plastic debris emits the scent of a marine infochemical, creating an olfactory trap for susceptible marine wildlife.