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Why do marine animals eat plastic?

Plastic pollution is well known to be a lethal ecosystem killer in the land. This reputation holds true in oceans as well. With each passing year, more number of whales are turning up dead on our beaches with their stomachs and intestines filled with plastics.

Why do deep-sea creatures like whales consume plastics? A simple question that is yet to have a conclusive answer.

Whales are deep-sea mammals that hunt for smaller fishes and crustaceans. In fact, they are classified into two based on what they eat: Baleen and Toothed. Baleen whales have plates that act as filters in their mouths to take in small krill and plankton. Toothed whales are the ones that hunt down seals and penguins.

Some believe that marine animals tend to mistake floating plastics to be food- maybe it resembles in smell. But that argument doesn’t hold for toothed whales as they hunt 1,600 feet below the sea level. Unlike other creatures, whales, the apex predators of the ocean are said to know what they are eating (or do they?).

What makes things interesting is that plastic waste doesn’t just keep on floating in the water. Many of them naturally sink, including bottles. Plastics that don’t sink will eventually be dragged down by the weight of algae growing on it.

Beached whales
Beached sperm whales in Germany via elitereaders.com

Matthew Savoca, a postdoctoral researcher at Hopkins Marine Station at Stanford University sees a different possibility here. He says “They(whales) use echolocation to hunt for food—typically squid. It’s possible, that plastic trash sounds like food to toothed whales.”

The sad thing about plastic ingestion is that its a slow poison. Whales are active animals that roam around the ocean. They hunt by diving deep, holding the breath they take from the surface. Each dive requires an enormous amount of energy.

If at least one or two of these dives results in plastic ingestion there is a significant imbalance of energy, making the whales less efficient. This could continue as a lethal cycle until the whale eventually dies.

Off the whales that end up beached and autopsied for plastic ingestion, most are toothed whales. Ballen whales are able to escape the effects of plastics, at least for now, as their filtered mouths block the entry of larger plastics. 

Long term effects in Ballen whales due to smaller particles of plastics are yet to be identified. Just to be clear whales are not the only animals that are being killed by plastics. From normal fishes to coastal birds all are affected by marine plastics. 

whales and plastics
Via WWF Australia

Maybe we don’t know why whales or other animals consume plastic. But we do know it will kill them. Plastic consumption has been rising from the day it was ever invented. In 2015 we produced 448 million tons of plastics and this number is expected to double by 2050. It is high time we stopped using plastics or at least dispose off it properly.

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