Why Do Ocean Animals Eat Plastic?


Stories of ocean animals washing up with their stomachs full of plastic are becoming increasingly more common with each passing year. It may seem strange that an animal will swallow a plastic bag or a straw, so what makes them do it?

Animals eat plastic because it looks similar to their normal prey. As algae grow on plastic, the smell of the algae will also attract animals that normally feed on it. Plastic can make animals sick and can get stuck in their stomachs. Plastic can also get caught around the bodies and necks of animals.

We all need to stop using plastic as much as we do, and I hope that by the end of this article you will understand some of the reasons why.

Do whales drink seawater?  Find out in this article I wrote

Why Do Ocean Animals Eat Plastic?

It was originally thought that marine animals ate plastic because it looks similar to the prey they eat. A plastic bag floating under the water surface looks a little like a jellyfish, which many whale and dolphin species will hunt.

Microplastics that break down in the water begin to resemble marine particles, which many fish and crustaceans would naturally feed on.

New evidence has shown that there is another reason ocean animals eat plastic, the smell. Algae is a vital food source for krill and other small sea creatures. As the algae break down, it emits an odor similar to sulfur, known as DMS (dimethyl sulfide).

Marine birds use this smell to find their hunting grounds, as the smells signal the presence of food. Unfortunately, algae grow very well on plastic, so the plastic floating in our oceans starts to smell like food to marine animals.

A sperm whale, often found in North American waters, washed up on the Scottish coast in 2019. An autopsy found that the whale had an astonishing 220 pounds of plastic in his stomach. It is believed he starved to death as his stomach was so full of plastic.

Want to know which wildlife lives around shipwrecks?  Find out here in an article I wrote.

How Does Plastic Affect Animals?

Small pieces of plastic may not cause a blockage or any internal injury, but they can make animals sick. The toxic chemicals can cause illness, infertility, and shortened lifespans.

Large pieces of plastic such as plastic bags or freezer pouches can get stuck in the stomach or intestines. Blocking the stomach means that animals stop feeling hunger, so they would gradually starve to death.

A blockage in the intestines stops other food from passing through. The animal would likely be in a considerable amount of pain and would feel incredibly weak. Sometimes the blockage may pass further along the intestines toward the bowel.

Even at this point, it is almost impossible for smaller animals to pass large pieces of plastic from their bodies.

Plastic bags can also get lodged in the respiratory tract, causing suffocation. Other plastic items can cause severe injuries. In 2015 a turtle was found with a plastic straw wedged up its nostril, severely restricting its ability to breathe.

Turtles and seabirds are often found with plastic can rings stuck around their necks, as are seal pups. As the animal grows, the plastic ring tightens around the neck, cutting into the skin and causing infections.

Turtle hatchlings are also at serious risk from plastics. As soon as a turtle hatches, it is drawn down the beach to the ocean. In many cases, they end up walking into plastic cups or bottles and get stuck. They often die due to their inability to get free.

One of the biggest causes of marine death is fishing gear. Whales, dolphins, sharks and turtles are all commonly entangled in fishing nets or abandoned fishing gear. This prevents them from reaching the surface for air, so they slowly suffocate.

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Many divers and biologists have reported finding multiple entanglements and spending hours trying to free marine animals from fishing nets.

Finally, it is important to note that plastic can travel thousands of miles. This means plastic from the other side of the world can end up in North American oceans.

This is dangerous for native marine life as plastics from other continents will carry organisms that are not native to the US. These organisms become invasive species, often competing with native marine creatures for resources.

This can cause the decline of thousands of ocean species native to the Atlantic and Pacific coasts of the United States.

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How Much Plastic Is In Our Oceans?

The amount of plastic in our oceans is doubling, on average, every decade. According to the Natural History Museum, a 2015 journal estimated between 4 and 13 million tonnes of plastic ends up in our oceans each year. This is likely to have risen even higher over the last six years as the world’s population increases and, with it, the demand for plastic products.

There is a patch of floating plastic in the pacific ocean between California and Hawaii that is roughly the same size as Texas.

Unfortunately, this is only a small percentage of a much bigger problem. Between the coasts of California in the US and Kuroshio in Japan, there are several so-called “garbage patches.”

Much of the debris in these floating patches are under the water surface, and a large percentage is microplastics, which are not easily visible to the naked eye. Many of the smaller patches end up joining larger ones due to strong winds or ocean currents.

According to the Ellen McArthur foundation, there may be more plastic than fish in our oceans by 2050. Several countries have recently taken steps to reduce the number of single-use plastics being produced, but the recent pandemic has put these plans on hold.

It is also estimated that approximately 230,000 tonnes of nurdles (plastic pellets) enter our oceans every year. Nurdles are used to manufacture plastic products and are consumed by ocean animals just as often as other plastic items.

Since the coronavirus hit in late 2019, most countries worldwide went into some form of lockdown. This put immense pressure on waste collection and recycling plants. In addition, many businesses were forced to use disposable or single-use plastics to comply with legislation. This only created more plastic waste and a reduced workforce to deal with it.

Even animals in the deep sea are not safe from plastics. In 2014 researcher Dr. Lucy Woodall found that many deep-sea creatures had high levels of plastic contamination. She also found similarly high readings in deep-sea sediments. This is caused by microplastics that break down in the water when exposed to sunlight, leaching plastic and other chemicals into the water.

It can take up to 2000 years for a plastic bag to start disintegrating, but even then, it would continue to break down, leaching toxic chemicals into the ocean. Those ocean animals that ingest plastics would be eaten by other animals, who would also be ingesting the microplastics.

Did you know that fish have an extra sense that other animals don’t?  Find out more in this article I wrote

The average person creates much more waste than we are aware of:

  • Newspapers and magazines
  • Letters
  • Envelopes
  • Tissue paper
  • Books
  • Printer paper
  • Water and soda bottles
  • Packing paper
  • Bubble wrap
  • Disposable plates, cups, and cutlery
  • Cleaning product bottles
  • Shopping bags
  • Bin liners
  • Cellophane/plastic wrap

We don’t give much thought to what we are using. While a growing number of people separate their paper, cardboard, and plastics for recycling, most households still bundle everything into one general waste bin, which is collected and taken to a landfill.

Plastics can end up in the ocean via littering, wind, illegal dumping of waste, fishing, or drainage systems.

There are four different groups of marine mammals.  Find out what they are in this article I wrote

References

Coastal Care. (2019, December 9). Why do ocean animals eat plastic? Retrieved from Coastal Care: https://coastalcare.org/2019/12/why-do-ocean-animals-eat-plastic/

Daly, N. (2019, December 6). Why do ocean animals eat plastic? Retrieved from Chris Hannah: https://chrishannah.me/why-do-ocean-animals-eat-plastic/

Ellen Macarthur Foundation. (2017, December 13). The New Plastics Economy: Rethinking the future of plastics & catalyzing action. Retrieved from Ellen Macarthur Foundation: https://www.ellenmacarthurfoundation.org/publications/the-new-plastics-economy-rethinking-the-future-of-plastics-catalysing-action

Flora and Fauna International. (2020). Help Beat Plastic Pollution. Retrieved from Flora and Fauna International: https://www.fauna-flora.org/appeals/plastic-appeal-dig?msclkid=da072b0297c519c475004b931070794e

Gooljar, J. (2018, April 5). Fact Sheet: Plastics in the ocean. Retrieved from Earth Day: https://www.earthday.org/fact-sheet-plastics-in-the-ocean/

Krosofsky, A. (2021, January 7). Plastic Pollution Kills Millions of Animals Every Year. Retrieved from Green Matters: https://www.greenmatters.com/p/how-many-animals-are-killed-by-plastic-pollution

National Ocean Service. (2021, February 26). What is the Great Pacific Garbage Patch? Retrieved from National Ocean Service: https://oceanservice.noaa.gov/facts/garbagepatch.html

Natural History Museum. (2020). How much plastic is in the ocean? Retrieved from Natural History Museum: https://www.nhm.ac.uk/discover/quick-questions/how-much-plastic-is-in-the-ocean.html

Ocean Crusaders. (2018, November 12). Plastic Statistics. Retrieved from Ocean Crusaders: https://oceancrusaders.org/plastic-crusades/plastic-statistics/

Parker, L. (2016, November 9). Animals Eat Ocean Plastic Because it Smells Like Food. Retrieved from National Geographic: https://www.nationalgeographic.com/science/article/animals-eat-ocean-plastic-because-of-smell-dms-algae-seabirds-fish#:~:text=Animals%20Eat%20Ocean%20Plastic%20Because%20it%20Smells%20Like,are%20gobbling%20up%20so%20much%20marine%20plastic%20debris.

Smith, L. (2019, March 27). How Does Plastic End Up in the Ocean? Retrieved from Naturaler: https://naturaler.co.uk/how-does-plastic-end-up-in-ocean/#:~:text=There%20are%20lots%20of%20different%20ways%20that%20plastic,if%20it%E2%80%99s%20disposed%20of%20inland.%20More%20items…%20

Bryan Harding

Bryan has spent his whole life around animals. While loving all animals, Bryan is especially fond of mammals and has studied and worked with them around the world. Not only does Bryan share his knowledge and experience with our readers, but he also serves as owner, editor, and publisher of North American Nature.

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