Nancy Treneman: When I was little, Mom showed me a hermit crab in a tide pool, and I was totally hooked on the ocean.

And so I've been coming out here since I was 10 years old.

That's one thing I love about marine organisms: You have to enjoy the world of the very small.

Nudi... You look and look and look.

Nobody's home.

Narrator: It's just after dawn, the lowest tide, and Nancy is looking for a creature about the size of a contact lens.

And you have to look and look and look again.

Let's see here.

Where are you, buddies?

Sometimes they're here and sometimes they're not.

Oh, wow!

Hey, cool.

Yeah!

First nudribranch.

There you are.

She is in search of nudibranch, a type of sea slug known for its wild shapes and colors.

Hi there, guys.

How we doing?

So this one, it's really beautiful.

It's white, and then the tips of the cerata are colored orange and they kind of glow in the dark.

Nudibranchs have eye spots where they can sense light and dark, but they cannot see.

Come here, lady.

[ shutter clicks ] It's such a shame that they can't see how beautiful they are.

Nancy makes detailed notes for each of her findings.

And if she needs to, she'll temporarily take a nudibranch back to the lab to identify.

I hate to disturb it, but... you'll come back tomorrow.

And, by the way, Nancy has a special permit to collect these nudibranch, which she'll return the next morning.

There you go, bud.

The really tiny ones are sometimes so hard to ID in the field, I have to take them in.

But I bring them back.

[ keys jingle ] Here we go.

Who's that?

Everybody's so pretty.

[ ♪♪♪ ] So nudibranch literally means "naked gill."

And their gills that they get oxygen from stick out of their back end, and they have fluffy butts.

Their gill plume looks like a little flower coming out of their rear end.

And the anus is in the middle of those gills, which is very odd because you're pooing where you breathe.

But... hey.

There are some 3,000 variations in oceans around the world, and Nancy has observed 69 species here in Oregon.

I think the thing that catches you the most is the nudibranchs' insane coloration varieties.

They're like the flowers of the ocean.

You can have nudibranchs that are solid black, nudibranchs that are fuchsia pink and glow in the dark, nudibranchs with spots, stripes, giant, feathery kind of forest-like cerata.

It's crazy.

Some of them have gizzard plates inside their stomach, like little teeth inside their stomach.

Some of them have huge, giant knobs all over their body.

Some of them you think, "Really?"

[ chuckles ] "Where's the head?"

You know?

And some of them look so odd that you just can't even figure out how evolution would produce that thing.

Their colors and crazy shapes are just part of their weird skills of survival.

The horn-like projections on their heads, called rhinophores, are sensors to smell food and find mates.

And as hermaphrodites, after mating, both participants can come away pregnant.

Their bright colors are not merely for style points but rather a tricky way to make predators think the nudibranchs taste terrible or are even poisonous.

And some even go a step further, actually stealing stinging cells from sea anemone.

Over time, they've evolved the ability to collect those stinging cells from the prey they're eating.

The stinging cells are then packaged and put into the nudibranch's skin.

And they keep those toxins in their body and those toxins kill the predator or they taste so bad that they'll spit them out or whatever.

It's crazy!

[ grunts ] Whoa!

Early the next morning, Nancy comes back at low tide.

She'll return the nudibranchs that she collected from yesterday right where she found them.

It's very important to never overcollect, always return what you can.

Always leave it exactly as you found it.

There you go, bud.

Because you want to monitor changes, I go through the same exact process every time, the same places, in the same order.

Because that way, as things change over time, I'm quantifying in the same way.

If I looked in different places all the time, then I wouldn't get a sense so much of the changes.

And as I get older, it gets harder and harder to do.

The more time you spend, the more you see.

My research and surveys basically go into quantifying who's there, how many are there, what kind of habitat they live in.

And that information is really important, because it is a snapshot in what we have now.

This part of the Oregon Coast is important for researchers like Nancy because it's where biological zones meet.

So the information that Nancy tracks of the very, very small can show changes on the scale of the ocean.

And so one of the uses of our data is showing how that overlap changes.

What we're seeing is the range shift of more southern organisms coming into this transition zone.

As the nudibranch diversity goes down or changes, that's indicating a demise of the whole thing.

So I think that they're a very good measure of ocean health.

With the tide rolling in quickly, Nancy needs to head back.

The spots where Nancy looked earlier are now underwater.

So there's a beautiful nudibranch down here, possibly too deep for me to get.

I knew he'd be here, but, whoa, I'm not going to be able to get to him!

She'd stay out here all day if she could.

And the tide is really the only thing that has the force to push her out... at least for now.

It's a joy.

It's a driven joy.

And when it comes to where I belong, it's the Oregon coast, but especially Arago.

And, um... it still makes me choke up every time I come.

[ gulls cawing ] It's a passion, and it goes beyond that.

It's a way of connecting to yourself, connecting to something deep inside you.

For me, it's clearly marine biology, but especially marine biology of the intertidal zone and the creatures and seaweed that live there.

[ camera shutter clicks ] Oh, they're so pretty.

And I think what gets me is when I go out in that tide pool and I see those lovely nudibranchs, I just am amazed.

There they are, doing their thing for thousands of years, and now I'm part of that.

[ ♪♪♪ ]