Mermaid tears, or mermaid's tears, are small pieces of plastic which float in the world's oceans. These tiny chunks of plastic may not look like much when held in the palm of the hand, but when one considers the fact that they are widely distributed in the oceans, they can seem a bit more ominous. Mermaid tears are only one among many forms of plastic polluting the ocean, but some biologists fear that they may be especially insidious, because they are ideally sized for consumption by filter feeding animals.

There are two types of mermaid tears. The first is a unit of plastic known as a nurdle. Nurdles are very small pieces of plastic which are designed to be melted down and them molded or otherwise shaped to make plastic materials, and they are widely used throughout the plastic industry. The most common source for nurdles is industrial spills from trucks and container ships; because nurdles are so small, they are hard to contain, and they slip away from containers and into waterways or into the ocean directly.

The other form of mermaid tear is a small piece of plastic similar in size to a nurdle, caused by the wearing down of finished plastic items. For example, if a broken plastic cup ends up in the ocean, the parts will slowly break up even further, turning into small plastic mermaid tears. Studies on the plastic debris in the ocean seem to suggest that mermaid tears only break down up to a certain point, and after that, they will float in the ocean for thousands or perhaps millions of years, potentially causing serious problems. As they get smaller and smaller, mermaid tears are harmful to more and more organisms in the sea, as well.

Mermaid tears are a problem for a number of reasons. The first and most obvious is that they are ingested by marine animals, who cannot digest plastic. As a result, animals can sicken or die with large numbers of mermaid tears in their digestive tracts, and bigger organisms may consume mermaid tears when they eat smaller organisms. As a result, plastic becomes widely distributed in the marine food chain.

Perhaps more insidiously, mermaid tears can also contain chemical pollutants. In addition to the chemicals naturally present in plastic, these small plastic pellets can also pick up other chemicals and contaminants, ranging from toxins to endocrine disruptors, and any organism which ingests these chemicals will suffer as a result. Mermaid tears are essentially like tiny toxic sponges with a deadly payload, and in some cases the effects may not be noticed for several generations, but they can still be quite severe.

Cleaning up the huge accumulation of plastic in the ocean is basically impossible, although it is feasible to collect larger bits of plastic debris. Most biologists are focused on beach cleanup, and on the reduction of garbage which could end up in the ocean. Some fear that it may already be too late, thanks to the proliferation of mermaid tears which would continue to hurt marine organisms for thousands of years, even if we stopped all plastic production today.