The Mystery of the Barreleye Fish
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The Mystery of the Barreleye Fish

August 18, 2019

Just off the west coast of the United States,
deep down in the Pacific Ocean, there lives a fish. And not just any fish. With its long, bulging eyes and transparent
head, the Pacific barreleye fish is a little… different. Biologists don’t actually know much about
it, because like many deep-sea animals, the barreleye is hard to catch, and even harder
to observe in its natural habitat, 600 to 800 meters below the surface of the ocean. But over the years, researchers have managed
to learn a little more, both from specimens that are hauled up to the surface in nets,
and — once — from catching the thing on camera. And it turns out that, unsurprisingly, the
fish’s adaptations are exactly what it needs to survive. First, there are its eyes. And no, I’m not
talking about those little black circles above its tiny mouth, where you’d normally expect
to find eyes. Because those are not eyes at all; they’re nares, which are basically
just nostrils. The fish’s eyes are actually those green
barrel-shaped things behind the nares, which give this fish its name… and look straight
out of the top of its transparent head The barreleye fish has what are known as tubular
eyes, because they’re shaped like tubes. And the fish uses them in a very particular
way. Eyes are often compared to camera lenses,
in the sense that they collect and focus light. The larger the lens, the more light it can
gather, which is important when you hang out in the dark depths of the ocean but still
need to be able to spot your prey. But for the barreleye, just gathering light
isn’t enough. Its tube-shaped eyes allow it to see farther away, like binoculars in
your head. They give the fish a fairly narrow range of
vision, but that’s okay, because most of the time, it only needs to look in one direction:
up. That’s because the barreleye fish lives
just below its prey. So in their natural resting state, the barreleye fish’s eyes are looking
straight up, scanning for food. In 2007, researchers from the Monterey Bay
Aquarium Research Institute managed to get a good look at a live Pacific barreleye fish,
and they discovered that its eyes have even more specific adaptations. For one thing, they’re green, which the
biologists think helps them better see their prey. We don’t know all that much about what these
guys eat, but scientists think they prey mostly on jellies and small fish. And jellyfish are often bioluminescent, meaning
that the barreleye is looking for their telltale glow. But as the fish stares upward looking for
food, even at those great depths, there’s still a lot of interference from sunlight,
which can be bright enough to outshine the bioluminescence. The green pigment in their eyes might act
as a kind of filter, taking the sunlight out of the picture and leaving only the glow of
tasty food. But once the fish has spotted its next meal,
it can still have trouble chasing it down. Researchers think that barreleye fish steal
their food from siphonophores, which often have tentacles with a powerful sting. A sting to a giant, sensitive, light-collecting
eye would not be a fun time for the barreleye fish, which is probably why it has that see-through
head. The head is filled with fluid, forming a shield
that protects the eyes from any stinging tentacles. Something else had been puzzling scientists
for a while, though: once it got its food, how did the fish actually eat it? Many animals with tubular eyes don’t really
move them around. But with its eyes always facing upward, the barreleye’s mouth would
never be in its field of vision. For a fish, that would make it tough to actually, like,
get the mouth on the food thing. The Monterey Bay researchers discovered something
that we’d never known before: the fish’s eyes can actually turn to look forward, which
they usually do if the barreleye’s body goes vertical. Meaning that as it swims upward toward its
food, the fish can actually rotate its eyes inside of its head to see in front of its
face. That makes it much easier for the barreleye to chomp down on its food. We still have a lot to learn about the Pacific
barreleye fish. But aside from the possibility of getting stung in the face at every meal,
life with a transparent head doesn’t sound half bad. Thank you for watching this SciShow Dose,
brought to you by our patrons on Patreon who help make SciShow possible. If you want to
help us keep making videos like this and get some pretty cool stuff, you can go to!


  • Reply Lavapop November 25, 2017 at 4:30 am

    So when the Barrel eye fish rotates how does it see the prey? through the nostrils?

  • Reply Backinblack Bunny November 29, 2017 at 2:17 am

    BARREL FISH ARE SHOW OFFS! "Oh look at me I have invisible skull, aren't I special." Yeah, whatever fish, I can lick my toes. Let's see you try THAT!

  • Reply Ben W December 2, 2017 at 4:08 am

    Real life is weirder than fiction. If you put that in a movie or book, who'd believe it? And yet, here's this fish swimmin' around with a see-thru head and funky barrel-swivel eyes, eating glow-in-the-dark seafood and jellyfish, and…yeah. Weirdly amazing stuff.

  • Reply Admiral Cat December 2, 2017 at 4:49 am

    But what if it goes vertically down, will its eyes be looking at the back of the head? Lol

  • Reply Doom Muffinz December 2, 2017 at 6:26 am

    Transparent heqd and internal eyes so theyre protected… very nice

  • Reply X T December 2, 2017 at 9:55 am

    Whenever I see this channel I think of sideshow Bob from the Simpson

  • Reply Ebrahim Jamshid December 2, 2017 at 3:23 pm


  • Reply Cameron Anderson December 11, 2017 at 2:45 am

    When I was very little,I first saw this weird fish while watching my favorite Disney jr show:Octonauts.
    It scares me by just looking at it!

  • Reply Tony Yerbajo December 11, 2017 at 8:33 pm

    Spanish subtitles >:(

  • Reply Chip Kosboth December 15, 2017 at 4:18 am

    Chasing it's prey down? Noooooo. Chasing it up! HA! I'll see myself out. And maybe their eyes act like nightvision goggles? The green. maybe… or not.

  • Reply Death Merchant December 17, 2017 at 3:37 pm

    researches and scientists say but then dam aquarium gets full name if your gonna quote specific sorces tell us who and what paper not just for your commercials …. and there are so many animals that eat without eyes at all and find there mouths why would you try to sensationalise this point. You personally have made pryor video on them. 👎👎👎👎👎👎👎 hold these people accountable for there actions people and there BS or at aleast make sure they don't influence your children.4.6 subs for this trype come on THINK WIYH YOUR EYES OPEN!👎👎👎👎👎👎

  • Reply Limitless Beast December 23, 2017 at 6:27 am

    I do not think it is the eyes that move to look forward but the mouth that rotates to face up and the body flows in the same direction.

  • Reply coc0s December 29, 2017 at 8:32 am

    Here's looking up at you, kid.

  • Reply BaRrElEyE FeSh January 2, 2018 at 12:04 pm

    FaVoRiTe FoOd: TiNy FiShEs & jElLyFiShEs,

  • Reply Brian Glassman January 3, 2018 at 2:25 am

    wow this fish makes me want to puke! And I am a scuba diver, Yuck !

  • Reply MrTingles January 15, 2018 at 3:24 am

    if we've got this level of strange on our planet, you better believe that if there ever were aliens stopping by for a visit, they'd look a lot stranger than little grey men with big heads.

  • Reply K9 January 19, 2018 at 7:41 pm

    Fun fact: This gnarly fish evolved its eyes during the 80s- because they are totally tubular, dude.

  • Reply Pokemon Ranger Philly January 25, 2018 at 5:32 am

    I wish shiny lantern looked like this barrel eye fish

  • Reply GhostShipSupreme January 29, 2018 at 11:26 pm


  • Reply The Jurassic Warewolf January 30, 2018 at 8:57 pm

    how deep is 600-800 meters in feet

  • Reply general kitten January 30, 2018 at 9:47 pm

    imagine that in subnautica

  • Reply Julius Bernotas February 1, 2018 at 3:54 am

    That creature is even uglier than blobfish

  • Reply TheSauceIsReal February 1, 2018 at 5:29 am feels like you got your information you got this

  • Reply mini February 7, 2018 at 10:15 am

    Evolution stole from subnautica.

  • Reply Pyrosong February 7, 2018 at 10:21 am

    Thanks! I hate it!

  • Reply Nayra Dharma February 12, 2018 at 2:42 pm

    This guy is so entertaining

  • Reply paramarthi555 February 18, 2018 at 3:40 pm

    why fishes need nostrils where are gills

  • Reply kmnbvc mnbvc February 21, 2018 at 6:13 am

    you could say its eyes are totaly tubular ……… ill see myself out

  • Reply Darwin Vortex February 21, 2018 at 2:46 pm

    Maybe it's green eyes acts like a nightvision? Just a thought

  • Reply Somebody Was-Here February 22, 2018 at 8:11 pm

    the fish looks like a normal fish with a can crushed into its face

  • Reply snabu Junkun February 24, 2018 at 11:25 pm

    With those hands of yours you can power an entire city.

  • Reply Decembirth February 25, 2018 at 10:23 am

    How about your favorite? The flounder, star gazer, or the barrel eye?

  • Reply DJ Professor K February 27, 2018 at 1:46 am

    Damn Nature, you scary!

  • Reply BLANK March 3, 2018 at 3:53 pm

    Am I the only who is still trying to convince my brain that those thing are eyes and the nare is not

  • Reply Jerry Mann March 5, 2018 at 4:10 am

    Many things have beeen learndt

  • Reply lil boost March 11, 2018 at 7:05 pm

    I still see the nostrils as eyes I can't not

  • Reply Dialysisforever March 14, 2018 at 7:08 am

    Does the Barrel Eye have a see through head because is steals food from the Man O War or does it steal food from the Man O War because it can, due to the see through head? Don't assume anything.

  • Reply Ron Eckart March 15, 2018 at 2:39 pm

    Heard of side show Bob? Well this is scishow bill

  • Reply Mr. HappyPineapple March 17, 2018 at 12:57 am


  • Reply Andrew Rojo March 17, 2018 at 8:39 am

    "a little"

  • Reply Name not found March 19, 2018 at 7:07 am

    kill it. kill it now.

  • Reply nunya efin biz March 20, 2018 at 8:24 pm


  • Reply Neb6 April 3, 2018 at 3:52 pm

    Delivered fresh from LV426 to you.

  • Reply - itsmeseer - April 22, 2018 at 8:19 am

    barreleye fishes live in the midnight zone right?

  • Reply raerambaran April 24, 2018 at 4:29 pm

    I love this guy

  • Reply GinkaV April 29, 2018 at 4:10 am

    What the actual fffff….????

  • Reply IYBJS 530 May 10, 2018 at 6:37 am

    For a fish that would make it tough to actually get its mouth on the food thing

  • Reply Morning Star May 13, 2018 at 1:03 am

    The fish is soo cOOL!

  • Reply KatsuraMu June 10, 2018 at 5:05 am

    hi and I have a bit of this message and then we have a lot of the new year and then we are the other day and then the last night year old and of the way home and I was in the new one year to the be a lot few days of the new York NY and I am so I am

  • Reply Alp er July 12, 2018 at 8:17 pm

    This was so scientific, like huge amounts of science, OMG, I'VE NEVER SEEN SUCH SCIENTIFIC program. This was so so so so much science. I almost became a scientist this was that much scientific.

  • Reply Niko sudijono July 29, 2018 at 7:31 pm

    The upshirt fish

  • Reply Shiboline M'Ress October 29, 2018 at 6:22 pm

    @ Barrelleye Fish: Captain Boday says hi! 🖖😃

  • Reply Mason Mugerian November 22, 2018 at 7:18 am

    it looks adorable

  • Reply Cammi Rosanov January 22, 2019 at 9:00 pm

    1:50 The cetacean institute where Gillian raised two humpback whales named George & Gracie. Later, all three were taken into the 23rd century aboard a Klingon Bird of Prey.

    Really go watch Star Trek 4. There is a long-shot of the Monterey Bay Aquarium almost identical to the picture.

  • Reply polemius01 January 31, 2019 at 5:21 pm

    Whenever I see anything about this fish, I remember what the 19th Century Midwestern US farmer said when he first saw a giraffe: "There ain't no such animal!"

  • Reply Macho Man Randy Savage February 5, 2019 at 10:21 pm

    They should rename it the Astronaut Fish.

  • Reply Abbieq11 February 6, 2019 at 2:32 am

    Tubular eyes sound totally tubular

  • Reply B Blessed April 13, 2019 at 5:43 am

    Need to update these older vids there's alot more known

  • Reply Moses Alazzawi April 14, 2019 at 5:12 pm

    I thought this was called a spookfish. I remember from a cartoon from when I was a little kid, the cartoon was called Octonauts.

  • Reply Lilith Eden April 27, 2019 at 8:43 pm

    This fish is no doubt the product of a long evolution. I wonder how it became this way. Lots of generations before this one must have had some strange mutation in the head that gave it an opportunity to fit some empty nice. It would be great if we ever got to know how its ancestors looked like. Evolution really creates the most amazing life.

  • Reply Mark May 3, 2019 at 3:46 am


  • Reply Ej Relatorre May 4, 2019 at 10:41 am

    This is one of my favorite kind of fish. Ooooooo, pretty inspiring for speculative evolution I'm working on!

  • Reply Rodrigo Andrés Beltrán Politeo May 6, 2019 at 11:36 am

    Hah spotting fish

  • Reply eric debord May 7, 2019 at 1:48 pm

    A video about an amazing fish and all you show is this fast talking dork. Here's an idea. Show the fish.
    Ya really, the story is about the fish so show the fish you idiots.
    Done with your channel. Done.

  • Reply Gerbil vids May 7, 2019 at 9:20 pm

    I used to terrified of these

  • Reply Galaxis May 9, 2019 at 7:58 am

    another fabulously bizarre adaptation and creature of this world. I find it instructive that such things can exist. It tells us something about how any life form exists.

  • Reply citizenschallengeYT May 12, 2019 at 1:41 am

    Sunlight at 600 meters?

  • Reply 8 wing May 13, 2019 at 4:24 am

    Weird flex but ok

  • Reply Griffith Andy May 13, 2019 at 3:47 pm

    I dont want to watch you talk. I want to see the fish.

  • Reply Griffith Andy May 13, 2019 at 3:49 pm

    4 mins, and only 2 short glimpses of the fish. Stupid

  • Reply the golden kids May 13, 2019 at 11:08 pm

    Wtf when was this discovered?

  • Reply C W May 15, 2019 at 5:08 pm

    Would have preferred you gave the fish majority of screen time instead of yourself talking. Not that you're not absolutely lovely to look at 😉

  • Reply Juan JM May 16, 2019 at 3:42 am

    First I was like "Cool, somoething new, I've never heard of such animal" but then I was like "Ugh, this is one of Hank Green's chapters e_e"

  • Reply Skunk Man May 19, 2019 at 9:29 am

    This fish is also called the spookfish according to the octonauts

  • Reply Roderick Lee May 25, 2019 at 4:39 am

    Does it taste good

  • Reply DATING HARLEY QUINN May 25, 2019 at 11:10 am

    ITS HARD TO CONCEIVE but male Barreleye fish are swimming around thinking female Barreleye fish are HOT AS HELL…………

    The same thing holds true for people in Alabama

  • Reply andres calderon May 25, 2019 at 1:58 pm

    Too much talk and movements

  • Reply tihzho May 26, 2019 at 7:05 am

    You and your annoying jump cuts!!

  • Reply chalmers wood May 27, 2019 at 12:26 pm


  • Reply Vo Filangi May 28, 2019 at 1:30 am

    There's something very annoying (to me) about the way the presenter sounds and enunciates. To the point where I can't even listen to what he says. I have issues I know lol

  • Reply jaxxstraw May 29, 2019 at 8:21 pm

    I too have long bulging eyes and a transparent head. It's not so bad.

  • Reply Her Imminence The Supreme One God June 1, 2019 at 7:23 am

    The proper name for this Pfish is, "Sharkes too tam." There are three kinds of these in the oceans and two kinds in the seas. Entirely; these each belong to certain sharks or and whales may share for. The Pfish are information-seekers for both the sharks and whales who are the GOD'S of the open waters. The Pfish are part of the skins and fleshes where the shark or and the whale keep them regionally close. Food for these informers' Pfishes is only krill.

  • Reply John Snow June 1, 2019 at 2:56 pm

    Always cool to see something this strange and different on earth gives you an idea of just how crazy life on another planet could be

  • Reply Wilmer Avilés June 1, 2019 at 6:00 pm

    Great narration, but show more of the subject and less of the narrator. We came to YouTube to SEE the subject, otherwise we can easily download a podcast or read it ourselves. Get over yourself and show the subject nearly 90% of the video.

  • Reply Trish Truitt June 7, 2019 at 7:09 pm

    This thing is THE best argument for Ancient Aliens playing genetic games of chance. My bet is this fish is featured on their version of Drunk History: Earth DNA edition.

  • Reply Karl Jensen June 27, 2019 at 3:06 am

    it would have been nice to see more the fish rather than this guy flapping his arms like a bird when he talks.

  • Reply Stacy Flood June 28, 2019 at 7:58 am

    I would have liked getting to see the fish a lot more, instead of a human. I see humans all day, but not barreleye fish…
    Show more of what you're talking about

  • Reply Dee Dee July 1, 2019 at 3:03 am

    Take a breath dude,longest sentence I ever heard,

  • Reply Lady Wolf July 4, 2019 at 6:00 am

    45 seconds of a 4 min video shows the fish ..
    Lame ..

  • Reply Bryan Carter July 5, 2019 at 3:12 pm

    Great info, but would have like to actually see the fish a lot more than just watching the guy talk. Show us the fish while you talk about it, JFC.

  • Reply C&C Phx July 5, 2019 at 8:49 pm

    Work on broken garbage truck nah I have to learn about this fish

  • Reply Eisenwerks July 7, 2019 at 4:16 am

    Glowy jellyfish: Look at my beautiful glow, world!
    Barreleye fish: Oooh I'm lookin'

  • Reply Blobbert Mcblob July 11, 2019 at 10:07 am

    So if it's head if transparent…where's it's brain?

  • Reply Rust belt Crawling July 20, 2019 at 12:03 am

    So they think !
    Okay so they don't know much about its vision !

  • Reply Nithesh PuZaN July 23, 2019 at 3:27 pm

    It's actually tiny alien submarine 😐

  • Reply Charlie D July 28, 2019 at 3:56 am

    I wanted to see a real live barreleye. . 🐟

    Not yapping four eyes! 👓 👀 👓

  • Reply Gordon Bricker July 28, 2019 at 4:53 pm

    GOD'S creation is awesome!

  • Reply Francisco Cepeda August 2, 2019 at 8:06 pm

    Can you actually show the fish while you talk ?

  • Reply perryandy2 August 5, 2019 at 1:12 am

    you know you could show the fish while you talk – you seem to need to upstage the fish

  • Reply Peter Stiff August 6, 2019 at 9:00 am

    More fish less dork please

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