When you're heading out for dinner, imagine mistaking a shoe for an octopus, or a plastic cup for a mackerel.

That's essentially what's happening beneath the waves.

Some marine life are getting tricked.

Researchers are asking why plastic confuses some of the ocean's most intelligent creatures.

Toothed whales like dolphins and other creatures that use echolocation to find food.

Welcome to the RV Shearwater.

It's a 77-foot research vessel dedicated to collecting troves of data on trips that last as long as a week.

They gather data using special equipment that includes some that they've even stuck on the bottom of the boat.

This is an echo sounder, and what it does is it uses different frequencies of sound to identify objects.

So like down here on the bottom we've got the seafloor, and these objects passing by underneath the boat are either fish or plastic debris, for example.

And what we used it for was to see the intensity of the signals.

So the question becomes, how is it that they are, or why are they eating plastic instead of food?

Are they misperceiving their acoustic senses?

Let's look at how echolocation works.

A toothed whale like a dolphin will send out a series of clicks to find out where the prey is.

The acoustic signals that bounce back tell them what's available to eat.

Since they swim shallow, dolphins use eyesight as well.

For other whales that go deeper to look for food, echolocation becomes more important since it's darker and they don't have any visual cues.

The density of the object correlates to what they call the intensity or target strength of the object, or how strong an object sends back that signal.

They've found that fish and plastic can sound the same to a whale.

On the top of their skull they'll have a melon, which is an organ that produces sound, and they use it just like sonar.

They're sending out sound signals and hoping it hits prey and bounces back to them.

And they interpret that sound through the lower jaw.

So there's fat on the lower jaw and that sound is received through the lower jaw and then goes up to the inner ear where it's interpreted by the brain.

So they are eating plastic.

But the plastic they're finding in whales isn't just coming from a case of mistaken identity.

It looks like a lot of it has already been in the food chain for a while.

So far he's found microscopic elements of things like polyester and plastic bottles.

Microplastics are ubiquitous.

They're everywhere.

The primary way that they're ingesting them is through what we call trophic transfer, meaning they are ingesting food that has already ingested plastic.

The fish have eaten the plastic, the squid have eaten the plastic, and then it ends up in the whales.

Scientists are learning more about the plastic problem by performing necropsy of dead whales.

They've also devised a unique way to collect tissue samples from these animals, and it helps them get a wider and more complete picture of what's going on.

So this is a crossbow and we use it to biopsy the animals, the whales.

So we take this modified bolt and it's got this tip on the end of it which will take a pea-sized sample of skin and blubber tissue from the whale when it hits it.

And then we'll take that tissue sample back to the lab.

That is for dinner.

What do we have here?

So this is our freezer where we keep a lot of our marine mammal samples.

Could you hold that up a little bit?

What is it?

So this is the dorsal fin of a pilot whale.

I know it's hard to see in the plastic, but it gives you a sense of the scale of how big a pilot whale is, about 18 feet.

Wow.

Blubber tissue is one of the really important ones we take.

So the outside layer is important for thermoregulation.

That's what keeps the animal warm.

And then the inside layer of fat gets mobilized and reforms.

This is the metabolic layer, the layer that's actually used for energy.

Take that sample out.

They need to dissolve the blubber using a special chemical agent and place it through a filter with holes about the size of the height of a CD disc.

This whole process takes about a week.

And you're looking kind of for like a needle in a haystack.

In this case, in the blubber tissue, we found maybe one particle in about a two-inch chunk of tissue.

So we don't have a good estimate yet of what that means for the whole animal, but we know that it is there.

No doubt.

In fact, they haven't arrived on an exact amount of microplastic these echolocating whales consume annually.

But a 2022 study estimated that other whales, like filter-feeding blue whales, might consume as much as 95 pounds of plastic per day.

Is there an answer to the problem of plastics and microplastics?

I mean, in my opinion, it's a policy solution.

We need to just stop using and producing as much plastic as we do.

There are real legitimate uses of plastic, like in the medical sector, keeping things sterile.

But things like single-use plastic, we just create so much unnecessarily.

With each discovery, researchers are getting closer to understanding how whales navigate a noisier, plastic-filled world.

That knowledge could help teach us all how to reduce our use of plastics so others can thrive.