Plastic is lightweight, durable — and wildly popular. We've produced 8.3 billion metric tons of the material since mass production began in the 1950s. Because it doesn't easily biodegrade, much of what we've made now lives in landfills like this one on Nairobi's outskirts. Rubbish pickers there hunt for recyclable plastics to earn a living. But a lot of plastic also ends up in the ocean ...

Much plastic enters marine habitats through rivers like, the Yangtze, the Indus, the Ganges, Pearl River, and the Mekong. These rivers run through highly populated areas with a lack of adequate waste disposal infrastructure. Here, a fisherman in the Philippines removes a fish and crab trap from plastic-filled waters.

Some animals have found uses for plastic waste. This swan nested in garbage on a Copenhagen lake that is popular with tourists. Her cygnets hatched surrounded by waste. It's not the best start to life. But for some animals the consequences are much worse ...

Although plastic is highly durable and can be used for products with a long lifespan, such as furniture and piping, about 50 percent goes to disposable products, including single-use cutlery and six pack rings that end up in the natural environment. Animals, like this penguin, are in danger of becoming entangled and dying as a result.

Other animals mistake the material for food. This albatross chick was found dead on Sand Island in Hawaii with multiple pieces of plastic in its stomach. According to one study of 34 seabird species in northern Europe, Russia, Iceland, Svalbard, the Faroe Islands, Scandinavia and Greenland, 74 percent had ingested plastic. Eating the material can lead to organ damage and blockages in the gut.

Even larger animals aren't immune to the effects of consuming plastic. This whale was found struggling to breathe and swim in a Thai canal. As rescuers attempted to save the animal, it vomited five plastic bags and later died. During the necropsy, vets found 80 shopping bags and other plastic garbage had clogged up the whale's stomach, so the marine creature could no longer digest nutritious food.

We're well aware of the large pieces of plastic bobbing on the ocean's surface, as is pictured here off the Hawaiian coast. But did you know, trillions of tiny particles less than 5 millimeters in diameter are also floating around in there? These particles end up in the food chain. Sea plankton, which are an important source of food for fish and other marine animals, have been filmed eating them.

Tentative measures to cut down on disposable plastic have already been taken in some African countries with bans on plastic bags, while the European Union is looking into prohibiting single-use plastic products. But if current trends continue, scientists believe there will be 12 billion metric tons of plastic on the planet by 2050.