Photo of brown and white star like coral polyps clustered closely together.

Coral polyps love the taste of plastic.

Coral polyps love the taste of plastic. 

Image: G. P. Schmahl, NOAA FGBNMS Manager.

Plastic waste in our oceans is a big problem for marine fauna. Not only can it look like food, it seems some animals have developed a taste for the material. And that’s a problem.

To a hungry turtle, a floating plastic bag can look awfully like a nutritious jelly fish. That rubbish becomes a serious problem once it slips down the poor animal’s throat.

Smaller animals can also gobble up tiny pieces of plastic drifting through the water. The tiny polyps that build coral, for example, have been found with plastic in their guts. Until now scientists haven’t been entirely sure why they’ve also been deceived into swallowing the stuff.

It turns out what seems like a dull, unappetising substance to us has a tantalising taste other organisms can’t resist.

American researchers began by handfeeding one-millimetre-sized pieces of plastic to coral polyps, to see if they’d treat it as food. Unlike sand particles, which the polyps brushed away, they blasted the plastic with tiny harpoons and reeled it greedily into their mouths.

Coral polyps don’t have eyes like us; instead, they can tell the difference between sand and a snack by using chemical sensors on their skin. That’s like tastebuds to you and me.

The researchers even conducted tests to see if there was a yummy coating of microbes attracting the polyps’ attention, but it turned out they preferred the scrubbed grains of plastic on their own.

Usually they spat the fake food out again within a few hours, but sometimes the pieces got stuck in their gut – which is bad news for the polyp.

The next step is to figure out exactly which additives or ingredients are making plastic so appealing. Meanwhile, it’s a timely reminder to recycle your waste, in case it becomes the last meal for some poor, hungry animal!

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