Plastic Smells Like Food to Sea Turtles

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There are many theories about why sea turtles and other marine animals ingest plastic. Some people have long speculated that they mistake it for food due to its appearance — for instance, turtles will eat a plastic bag that looks like a jellyfish

It makes sense that sea turtles could confuse clear bags for jellyfish and bits of green rope for seagrass, but it doesn’t explain the countless other bits of plastic found in turtles’ stomachs when examined.

Dr. Joe Pfaller and colleagues from the University of North Carolina at Chapel Hill decided to investigate another sense that turtles use often when looking for food- scent.

The study shows that the scent of bacteria and other microorganisms growing on ocean debris might be luring turtles in, too. 

Like most things floating in the ocean- algae, bacteria, and plants quickly find refuge on floating plastic fragments. Turns out, these growing organisms release the same chemicals as the ones sea-dwelling animals follow to locate food.

This spells BAD NEWS not just for sea turtles, but many other oceanic creatures.

How Was The Study Conducted?

Fifteen loggerhead turtles, all raised in captivity, were brought into the lab where biologists released four scents into tanks where each turtle was swimming. If the turtle poked its nose out of the water and inhaled (a behavior often noted as a ‘feeding response’) the team took that to mean that the turtle was interested in what that scent was. What was interesting, was the turtles responded differently to certain smells.

What Did The ‘Sniffs’ Tell Scientists?

When the turtles smelled plain water or clean plastic, they only spent a few seconds with their nose in the air. When the scent of turtle food was introduced, the time with their nose out of the water was three times longer. . . . And the scent of plastic that had soaked in the ocean for five weeks? The turtles reacted the same as they did to the scent of food!

“The turtles know the smell of their food since they’ve been smelling and eating it in captivity for five months. I expected their responses to food to be stronger,” said University of Florida biologist and co-author Joseph Pfaller in a press release. “We were surprised that turtles responded to odors from biofouled plastic with the same intensity as their food.”

Just another reason to REDUSE our use of plastic. Over 90% of all plastic created since the 1950s is in our landfills and environment. According to the NOAA website, 8 million metric tons of plastic enter the oceans every year- the weight of nearly 90 aircraft carriers (those massive ships the military uses to haul jets); 39,400 Statue of Liberty’s; or 705,000 school buses. EVERY YEAR. And plastic never goes away, it just gets smaller. So, yes, when everyone can even cut down a little. . The amount adds up to massive proportions.