Plastic debris are threatening sea turtles in the oceans worldwide. In an article published in Current Biology, scientists explain why they mistake plastic for food.
The researchers found that loggerhead sea turtles react to the smell of plastic in the same way they react to the smell of food. According to Joseph Pfaller of the University of Florida, this explains why these animals regularly end up ingesting or getting trapped in plastic debris.
In the past, researchers believed that sea turtles were visually attracted to plastic, perhaps mistaking them for other animals like jellyfish. However, this research indicates that they respond to the smell of the material, not to what it looks like.
Why are they attracted by the smell of plastic?
When plastic spends a lot of time in the ocean, small animals, plants, algae and microbes accumulate in it. This process is called biofouling, and it produces an odor that confuses sea turtles and makes them think that plastic is food.
A curious fact is that odor-releasing substances produced by predators also emanate from plastic debris.
To find out how turtles react to certain types of odor scientists were helped by 15 young captive loggerhead sea turtles.
They set up an environment to carry out the experiment, and using a pipe they released various odors into the air while recording how the turtles reacted in response to each one.
At the end of the experiment, they concluded that sea turtles react to food in the same way that they react to biofouled plastic.
“We were surprised that turtles responded to odors from biofouled plastic with the same intensity as their food,” Pfaller mentions. “We expected them to respond to both to a greater extent than the control treatments, but the turtles know the smell of their food since they’ve been smelling and eating it in captivity for 5 months. I expected their responses to food to be stronger.”
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“The plastic problem in the ocean is more complex than plastic bags that look like jellyfish or the errant straw stuck in a turtle’s nose,” he adds. “These are important and troubling pieces to the puzzle, and all plastics pose dangers to turtles.”