And those bright green specks inside their bodies are showing us what they're eating.

It's not food.

Those are tiny pieces of...plastic.

We hear a lot about pollution from single use plastic items,

like plastic straws and shopping bags that are clogging marine habitats.

Although these large pieces of plastic contribute the most to the overall mass of plastic polluting oceans,

they count for a small share of the total number of plastic particles.

That's because most of the plastic pieces in the oceans don't look like this.

They're tiny particles that look like this, and where they're coming from might surprise you.

“Modern fibers, alone or in blends with natural fibers, brought new innovations in cool, crisp comfortable clothes.”

Back in the 1940s, fabrics like nylon, acrylic and rayon-- all made from plastic -- became really popular.

These synthetic clothes were cheap to produce, comfortable to wear,

and as more people have bought clothes for athletics and leisure,

companies have been making more clothes out of plastic.

By 2010, over half of all the fabric in our clothing was made from synthetic fibers.

In the meantime, marine scientists noticed that habitats were being polluted with tiny pieces of plastic called “microplastics”.

These are objects are smaller than 5 millimeters,

and can be anything from tiny shards broken off larger items to microbeads developed for use in cosmetic products.

Microplastics are found in marine habitats everywhere on Earth.

Concentrations of microplastics have been found on coastal beaches in South Africa,

The Great Lakes of North America, rivers in Britain,

and at the bottom of an oceanic trench near Russia.

Turns out, a large share of those microplastics are microfibers:

tiny strands of plastic, and they're coming from our laundry.

Looking at this fleece jacket up close,

you can see that its fuzzy material is actually a fabric made from tiny strands of plastic woven together.

When we wash a synthetic piece of clothing,

like this fleece, the fabric is pulled loose and tiny microfibers fall out.

Scientists actually tested three types of synthetic clothing to see which types shed the most using a washing machine fitted with a special filter.

They determined that acrylic shed the most microfibers.

Over 700,000 on the first wash alone.

And even though fiber loss goes down after the first wash, the sheer number of people doing laundry adds up,

making microfibers a huge contributor to the nearly five trillion pieces of microplastics that are floating around the world's oceans.

In most dryers there's a mesh screen to catch lint, but washing machines typically don't have a filter.

So everything that falls off our clothes is flushed down the drain.

From there, microfibers might move through a sewage treatment plant,

but the filters are often too large to stop them from passing through and flowing to a discharge point at a nearby marine habitat.

Once they reach the ocean, microfibers are consumed by plankton and other filter feeders that eat debris falling to the seafloor.

And then the plastic starts making its way up the food chain,

passed on by predators feeding on organisms that have ingested microfibers.

Eventually, it reaches us.

Plastic enters human bodies when we eat seafood containing microfibers.

Like these, which scientists found in a piece of fish they bought at a seafood market.

So, what can be done?

Switching to other materials isn't feasible because synthetic clothes -- they're cheap.

A lot cheaper than making apparel with other fabrics.

But what you can do is add a filter to your washing machine that would catch microfibers falling off when you do your laundry.

Problem is, those are pretty expensive,

So another solution is using filter bags that trap microfibers before they fall off into the wash when you do your laundry.

But the most effective change of all would just be buying fewer synthetic clothes,

or at least, washing them less often.

And what less often means...

that's up to you.

If you've gotten to this point in the video,

you're probably the kind of person who would be curious in learning about something like astronomy.

You know, what's out there in case we need to abandon this plastic-filled ship of our own making.

Brilliant is a problem solving website that teaches you how to think like a scientist.

They have courses on everything from calculus to astronomy and daily problems in math and science.

To learn more about Brilliant, go to Brilliant.org/Vox and sign up for free.

The first 200 people that go to that link will get 20% off the annual premium subscription.

So you can view all the daily problems and unlock all the courses.

Brilliant doesn't directly impact our editorial, but their support makes videos like this one possible.

So go check them out and thanks for watching!