Name: Are Sea Otters Colorblind? A Marine Biologist EXPLAINS!
Uploaded: 2025-08-12T17:39:15.000Z
Duration: 11 min 9 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

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I'm your host, KP, a marine biologist with over a decade's worth of experience working with marine mammals.

Recently on this channel, we took a look at how I trained Joey, the famous sea otter, how to spin.

Many of my followers here and over on my Twitch channel happen to notice though that the target pole I use to guide Joey through that behavior is the color red.

Our uniforms are red, some of Joey's favorite toys are red.

That's led a lot of people to ask, is there a reason that we use red?

Do sea otters have a certain affinity for the color red?

What do you possibly have to complain about?

This has led to a new series on our deeper dive into animal senses, and we're going to start with eyesight.

But first, of course, your obligatory reminder to like this video and hit that subscribe button.

Hit the bell to be notified when we go live.

You can also head down to the descriptions below for sources that we cite from our research.

Now the topic of eyesight actually covers a lot more than just color.

There's a lot to unpack here, but we'll start with color because it's a very popular question.

Do the sea otters recognize the trainers because we wear the color red?

It's actually no, because sea otters are red, green, colorblind.

So let's take a look at that famous clip of Joey screaming in my face.

And we'll look at it from the eyes of a sea otter.

This is actually more color than most marine mammals can see seals, sea lions, walruses.

They all basically only see in shades of blues and greens.

Watch how we color grade this video to show how fur seals view their environment.

There's a very good reason for this, and it's actually the answer to a popular question.

Water is about 800 times denser than air, which means that it absorbs light very quickly.

However, the rate at which it absorbs the light actually depends on the different wavelengths.

Colors with longer wavelengths or lower energy are absorbed much faster than those of shorter wavelengths and higher energy.

The wavelength of light gets shorter and more energetic the further down the rainbow that we go.

The first letter is R, representing red, meaning that red disappears first in the water.

In fact, in depths as shallow as 15 feet, red can completely disappear.

The next color to go is orange, which fades at about 25 feet and is closely followed by yellow, which disappears at 35 feet.

Purple and blue have the shortest wavelengths, thus the most energy.

So they are the last to fade out at around 110 feet.

There is some variation depending on how cold, clear, or murky the water is, but this is essentially why the ocean is blue.

The water is filting out all those warmer red and orangey tones and leaving behind the cool blues, greens, and purples.

It's also why the majority of marine mammals are colorblind.

In one of my favorite deeper dives, we took a look at just how deep some marine mammal species can dive.

And we learned that sea otters can actually dive as deep as 85 feet and routinely depths of 20 and 30 feet are recorded.

This means they honestly have little to no use for the color red and that's why they don't dive as deep as other marine mammals do.

In that same video, which you can see if you click on the link right up here, we also learned that seals, sea lions, and walruses often dive to hundreds, if not thousands of feet deep, meaning that the only colors they really need to see are different shades of blue.

Earlier though, I mentioned that color is only one aspect of sight.

You might be surprised to learn that sea otters and other marine mammals are actually near-sighted when they are above water.

On land, sea otters see about seven times less clear than a human with 20-20 vision.

So if you need corrective lenses, like I do, and your prescription is somewhere between minus two and minus three, then without glasses, you see a bit like a sea otter.

The same is true for seals, sea lions, and walruses.

But just like with color, there's actually a good reason for this near-sightedness above water.

Because underwater, it's a completely different story.

Water itself almost acts like a corrective lens.

That's because water refracts light in a different way than air does.

In fact, objects underwater appear 25% closer and 33% larger than they actually are.

In addition, there's little use for farsightedness underwater because the range of vision there is very limited.

In fact, even in extremely clear water, the range of vision is still limited to only a couple hundred feet.

So being near-sighted is actually a bit of an advantage for animals like sea otters.

Furthermore, sea otters have an ability that borders on a superpower.

And it's found in most animals, including humans.

Accommodation is the process that changes the eye's optical power to maintain clear focus on an object as it varies in distance.

A flatter lens helps focus on an object further away, while a rounder lens helps focus on an object that is closer.

Sea otters have one of the highest accommodations measured in vertebrates.

It is significantly more powerful than humans.

In fact, only freshwater otters and diving birds like cormorants have a higher level of accommodation.

And what it does for sea otters is it compensates for the way that light bends differently underwater.

It allows light to properly reach the retina, enabling a clearer image.

This can be a little tricky to visualize, so let me paint a picture.

Have you ever tried to open your eyes underwater?

It's pretty blurry if you're not wearing swim goggles.

Well, by squeezing their lenses through their pupils into a more rounded shape, sea otters essentially create built-in swim goggles, allowing them to see clearly while underwater.

We'll come back to sea otters in a moment, but for a second I want to talk about seals and sea lions who have a very similar adaptation that allows them to see underwater.

Specifically, I want to talk about fur seals.

People are often surprised to learn that fur seals like Tuku here are nearsighted and colorblind, even with these enormous and beautiful eyes.

But just like sea otters, they're perfectly adapted for life underwater.

Fur seals routinely dive to depths of 300 to 400 feet, meaning there is little to no light down there.

So their eyes contain a high number of rod cells.

These are sensitive to black, white, and gray pigment levels and very low levels of light.

In Dungeons and Dragons terms, they have dark vision.

In addition, their lenses are large, round, and perfectly adapted for picking up refracted light underwater.

While their eyesight is perfectly adapted for foraging and navigating their underwater world, especially when you consider their short, stubby arms and how their food is fixed to the ocean floor, they primarily rely on a completely different sense when underwater, and it has to do with their whiskers, which will be the topic of our next deeper dive.

And in case you missed our joey training video or you just want to watch it again, you can click on the card that's going to show up on this side at the end of the video.

In the next video, we're going to talk about In the meantime, let me know if you have questions in the comment section down below.

Maybe I'll even answer them in a short video or two.

Don't forget to like, subscribe, so you'll be notified when our videos go live.

But for now, enjoy these clips of the sea otters while I thank my Patreons, and I'll catch you next time.

I don't know that I can say it without saying earlier dough.