How smart do you think fish really are?

Fish have been evolving since the earliest age of vertebrates, but even among biologists, they have not been considered particularly intelligent creatures.

However, research on fish brains and behavior, which has advanced dramatically in recent years, has begun to overturn such conventional thinking.

The brains of fish have all the same regions as humans.

Fish might have greater intellectual abilities
than previously thought.

One of these is "mirror self-recognition," the ability to recognize your own image in a mirror.

Apart from humans, this advanced ability has been confirmed in animals that are considered particularly intelligent, such as chimpanzees and dolphins.

But it was recently revealed that there are also some fish with this ability.

In this episode, we'll take a closer look at what the latest science can tell us about the intelligence of fish.

Your impression of fish might change completely!

And later, we'll introduce a Takumi who has developed a special 3D printer that can mold food.

Stay tuned to find out how it works!

Hello, I'm Tomoko Tina Kimura.

Welcome to Science View.

Today we'll be looking at the amazing intelligence of fish.

And joining me is Mr. David Hajime Kornhauser, Director of Kyoto University's office of Global Communications.

It's nice to see you, Mr. Kornhauser.

Thank you for having me.

Now, fish are very familiar creatures.

I used to have a pet goldfish named Phoenix.

They're enjoyable to watch.

Yes, I also enjoy watching them.

Growing up in Hawaii, I used to enjoy swimming with tropical fish in the ocean.

Oh, that's nice Now, although fish are very familiar, I didn't have the impression that they were particularly intelligent.

Yes, this has been the view even among experts until recently.

But recent research has shown that there are several species of fish that are quite intelligent.

It's an amazing discovery that overturns conventional thinking.

First, let's take a look at a delightful aquarium show that demonstrates how smart fish can be.

This is Uozu Aquarium, in Toyama Prefecture, where you can watch fish perform tricks.

Uozu Aquarium is Japan's oldest aquarium, and has been around for over 100 years.

First to appear is the striped beakfish, a fish that lives in the seas around Japan.

It will pull the sign when the keeper gives the signal.

Show them what you can do!

It is using its mouth to deftly pull the sign.

The striped beakfish's message is:
"Welcome to Uozu."

The audience can clearly see the message.

Next up is the black scraper.

It will swim through some rings.

You can do it!

The fish moves precisely, following a human signal.

It certainly seems to remember what it should do.

This is the backstage area of the fish show.

Takuro Izumi is the keeper in charge of the show.

How does he get fish to learn tricks?

Izumi is also in charge of the seal show.

He says that the way of getting fish to learn tricks is no different to that of seals.

Seals are rewarded with treats and pats
when they do what you want them to do.

We try to reward fish in the same manner.

I think the ability to learn is the same
for both seals and fish.

Wow! I don't think I have ever seen fish perform tricks following human signals!

Mr. Kornhauser, have you?

Well, I have seen a dolphin show before, but not fish performing tricks.

That's very interesting.

I'd like to visit that aquarium someday.

Those fish were able to perform their tricks, but it's even more interesting when a fish fails to perform a trick.

For example, the black scraper, which went through the rings earlier, sometimes fails to do so.

Oh, it didn't go through the green ring.

No, but if it makes a mistake, it goes back to the start and tries again.

Wow! So clearly it knows the difference between failure and success.

Next is an experiment which found that some fish distinguish between friend and foe, or recognize their partner, based on the small differences in the patterns on their faces.

Let's take a look.

We've come to a laboratory at Osaka Metropolitan University that is investigating the intelligence of fish.

This is Dr. Masanori Kohda, who specializes in fish ecology.

Through various behavioral experiments, he has discovered a number of intellectual abilities in fish.

One of them is the ability to recognize each other accurately.

Kohda believed that territorial fish living in African lakes had the ability to identify other fish.

What are they using to identify other fish?

They look at the patterns on their faces.

Take, for example, this fish called a cichlid, which is about 10 centimeters long.

Cichlid's faces have a yellow, brown, and light blue pattern, which differs slightly for each fish.

Using a computer, Kohda cut and pasted the face of a different fish to create two images.

The original photo is the face of a familiar fish.

The second photo has the face of an unfamiliar fish.

These two photos were shown through the glass of the tank, and the cichlid's reaction was studied.

He found that the cichlid spent a different amount of time looking at the fish in the two photos.

It was wary of the unfamiliar face and looked at it three times longer than the familiar face.

Kohda has also conducted experiments with fish living in other areas.

The discus fish lives in the Amazon River in South America.

Once a male and a female make a pair, they stay together for a long time.

When a photo of the partner's face is shown through the glass of the tank, the Discus fish lines up its body side-by-side with the photo.

It's trying to swim alongside its partner.

This is a typical greeting behavior seen in pairs.

On the other hand, this Discus fish has seen an unfamiliar face through the glass.

This time it is trying to poke the photo.

This is an aggressive behavior.

In both cases, the Discus fish is using facial patterns to identify the other fish.

These experiments have shown that some fish have the ability to accurately recognize other fish by their faces.

So they can recognize subtle differences in facial patterns...

To be honest, I don't know if I could tell those fish apart.

I am very impressed with their ability.

I agree.

According to Kohda's research, they can identify another fish in 0.4 seconds.

That's actually no different than humans.

Kohda also examined several other species of territorial fish, and found that they have the same ability.

However, it seems that fish that migrate across the ocean in large schools, like the Pacific saury and tuna, do not recognize individual fish.

This might be because there are no particular differences in the faces of such fish.

Now, you may be wondering to what extent the fish brain is able to recognize and process its surroundings.

Let's hear about the latest surprising research.

Dr. Naoyuki Yamamoto is a professor at Nagoya University.

He's a leading researcher on the brains of fish.

He has studied the structure and function of the brains of more than 50 species of fish.

This is the part of the fish brain that corresponds to the human cerebrum.

It was previously thought that it only received and processed signals from the sense of smell.

However, research by Yamamoto and his team showed that it processes a variety of senses, including sight and hearing.

Therefore it may have a similar functionality to the human cerebrum.

People might think that fish are inferior,
but they are vertebrates just like humans.

Their brains have all the same regions
as the brains of humans.

Fish likely have greater intellectual abilities
than previously thought.

Yamamoto says that the fish brain may work in a more complex way than previously thought.

I think we can assume that
there is something like emotion at work.

For example, when they see an enemy,
they have a feeling of fear, and swim away.

If they see food, they have a feeling of
wanting to eat it, and then do so.

It's interesting to learn that fish have the same regions of the brain as we do.

The professor also says that they might have feelings!

In the past, animals were thought to be smarter if their brains were larger, or if they had a neocortex that was responsible for thinking and making decisions.

Fish don't have a neocortex, but they do have an equivalent area of the brain.

And there's an even more interesting study.

As we mentioned earlier, in 2019 Kohda discovered that fish have the ability of mirror self-recognition.

Mirror self-recognition.

That's the ability to recognize your own image in a mirror.

When shown a mirror, most animals regard it as another individual of the same species.

But some animals gradually recognize themselves.

This is an advanced ability possessed by a limited number of species, such as monkeys.

Kohda's research has shown that some fish have it too.

The ability to recognize one's own image in a mirror is known to exist mainly in chimpanzees, dolphins, and elephants, in addition to humans.

However, thanks to Kohda's research, it was found in a 10-centimeter-long fish called the "Bluestreak cleaner wrasse," which lives in tropical and subtropical regions

such as the Pacific and Indian Oceans.

The Bluestreak cleaner wrasse is known for its habit of eating and cleaning parasites from the bodies of larger fish.

The experiment of showing a mirror to a Bluestreak cleaner wrasse was recorded in detail by a high-speed camera.

The right side of the tank is a mirror.

When the cover is removed, the wrasse mistakes the image in the mirror for a rival, and attacks.

It rushes at the mirror repeatedly.

However, after about 20 minutes, it starts to peer at its own reflection in the mirror.

It seems the fish has realized that it might be looking at its own image.

After that, it starts to move more intensely.

It is making sure that the image in the mirror is moving in the same way.

This sequence of attack and confirmation is typical behavior also seen in the mirror tests of other animals, such as chimpanzees.

In order to confirm whether or not the wrasse is really able to recognize its own image in a mirror, Kohda decided to use the unique ability of the wrasse to spot parasites.

A brown mark, that looks like a parasite, is placed on the throat of a wrasse, and the mirror is revealed.

The wrasse frequently checks the mark on its throat in the mirror.

After that, it rubs its throat on the sand.

It thinks it has a parasite on its throat and is trying to remove it by rubbing it.

From this, Kohda concluded that the wrasse does indeed recognize its own reflection in the mirror.

What an interesting experiment!

The fish was clearly trying to get rid of something, just like a human would after looking in the mirror and noticing something on their face.

When it looked in the mirror, it couldn't help but worry about its throat.

When Kohda tried the same experiment on the wrasse again, it realized that it was a mirror-image faster than the first time.

It was able to recognize itself almost immediately.

So it had learned from what it had experienced before.

Yes, in addition to using mirrors, Kohda has also conducted some other interesting experiments.

Here is one in which fish behave "emotionally," like humans.

This is a Convict cichlid, a freshwater fish.

Once paired, these fish maintain a strong bond and breed together many times.

This kind of fish is used in the experiment.

First, a special tank is prepared, with a central partition, and two smaller chambers.

A male and a female fish are put into the tank, facing each other.

The partition is transparent, so they can see each other.

The two chambers in the male's half of the tank have doors marked in blue and red.

If the male enters the red chamber, he receives some food, but nothing special happens to the female.

On the other hand, if the male enters the blue chamber, he still receives some food, but this time so does the female.

Let's see what happens.

This is video of the actual experiment.

The male is in the foreground and the female is in the background.

When the male entered the red chamber, he received some food.

However, the female did not.

This time the male entered the blue chamber.

Both the male and the female received some food.

Once the male understood how this works, it chose the blue chamber almost 100% of the time.

In other words, it behaved in a way that allowed its partner to eat.

There's more to the experiment.

An unfamiliar male was put in the opposite tank, that had previously contained the female.

In this case, the original male was less kind, and entered the red chamber so that only he was fed.

Next, an unfamiliar female was put in the opposite tank.

This time the male entered the blue room and both received food.

Then, the original female partner was placed in an adjoining tank.

What will the male do now that his partner is watching?

Funnily enough, in this case he didn't go into the blue room to feed the unfamiliar female.

This leads Kohda to believe that some fish have advanced emotions, such as caring for others.

That was a really interesting experiment to watch!

There seems to be a lot of drama between males and females in the world of fish too!

In the second case, the behavior of the male may look like cheating, but this is because he may need to mate with a new female if his current partner dies.

By enabling the female to get food as well, the male hopes she will lay lots of eggs.

We think that this motivation may have evolved in the early days of vertebrates.

So fish may have been displaying this kind of behavior long before humanity appeared on the scene.

They're incredible creatures!

Up next, our Takumi/J-Innovators corner.

Today's topic is about 3D food printers.

In recent years, 3D printers have been gaining popularity.

Heated, softened material is extruded through a thin nozzle and built up in layers to create a desired object.

3D printers are now being used in a surprising field.

This is Yonezawa City in Yamagata Prefecture.

We visited a laboratory at Yamagata University to meet today's Takumi Doctor Masaru Kawakami.

Kawakami is looking at some kind of brightly-colored snowflake.

What could it be?

This is a carrot produced by a 3D food printer.

Believe it or not, he has printed a carrot!

How did he print a carrot in the shape of a snowflake?

Here's how.

First, data for the snowflake shape is entered into a computer.

Next, carrots which have been heated and finely mashed are mixed with water.

Rice flour is added to make the paste more viscous.

It's then put into the 3D food printer's tanks.

When switched on, the printer extrudes the carrot paste using the data from the computer to create a three-dimensional shape.

A carrot snowflake can be printed in about 5 minutes.

This 3D food printer has two nozzles that can extrude food paste.

This means two pastes with different colors and hardness can extrude separately.

The yellow paste is the mashed Kabocha squash flesh, and the green paste is the mashed Kabocha skin.

By extruding and molding the two pastes one after the other, he has recreated a slice of kabocha.

Now, three types of vegetables - Carrots, Kabocha, and Broccoli - can be 3D printed.

But why does Kawakami mash vegetables and then print them?

I'd been working with local food and
souvenir shops to create interesting shapes.

A nursing care food manufacturer suggested that
they could use this technology, so I began developing a 3D printer
for nursing care food.

Nursing care food is intended for the elderly and people with disabilities.

Sometimes, it's made into a paste so that it can be easily swallowed without chewing.

However, these pastes lack texture and appear unappetizing, which means people don't enjoy their meal and their appetite diminishes.

Kawakami wanted to make nursing care food that was easy to swallow and resembled actual food.

Originally, he was conducting research on the molecular structure of proteins.

He developed a method to build molecular models of proteins using 3D printers.

This led to 3D printers being used in research more often.

Hoping to contribute to Yonezawa's tourism industry, he built his first 3D food printer, and collaborated with another researcher to make jelly in the shape of a Carp.

He then received a proposal from a manufacturer of nursing care food, but there was a big challenge to overcome.

Some 3D food printers use a medical syringe to extrude the food paste.

But since air inside the syringe cannot escape, any air bubbles that come out during extrusion will affect the printed object's shape.

It's also time-consuming to keep replacing the syringe when the paste runs out.

So Kawakami stopped using Syringes and developed a new screw for 3D food printers, which is used to pump out the food paste.

With a screw, the top of the tank is open, so air bubbles can escape and will not mix with the paste.

It also allows you to add more paste before it runs out.

Four years after he started on the first machine, he completed the 3D food printer we have today.

He aims to introduce it into nursing care settings by 2025.

In the future, when I need nursing care too,
I want to eat food that looks and tastes nice.

I'd like to contribute to the improvement
of nursing care food any way I can.

Here I have a plate of 3D printed food.

This is "nursing care food" and I'm going to try out the carrot.

So, it's very soft.

Oh! It's very nice, and I can taste sweetness of the carrot.

Importantly, it looks much more appetizing than mashed carrots!

So, I can see how this would be greatly appreciated by those who need nursing care food.

Mr. Kornhauser, would you like to try the Kabocha?

Sure, here we go.

Both the skin and the flesh are beautifully reproduced and really look appetizing.

I hope that food made with this 3D food printer will be widely used in nursing care facilities.

Today we learned a lot about the amazing intelligence of fish.

Mr. Kornhauser, what are your thoughts about today's topic?

It's interesting to think that the various abilities and intelligence of fish discussed today may have existed 400 million years ago.

It's long been thought that only humans possess such things as consciousness, emotion, and compassion, developed in the course of biological evolution.

However, since ancient times, they may have already been present in creatures such as fish.

I'm looking forward to hearing about future research.

Thank you very much for joining us today, Mr. Kornhauser.

Thank you as well.

And that's all for today's Science View.

Thank you all so much for joining us and please stay tuned for our next program.