Claire Corlett

Fish Food, Fish Tanks, and More
The Mystery of the Barreleye Fish

The Mystery of the Barreleye Fish

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!

100 comments on “The Mystery of the Barreleye Fish

  1. 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!

  2. 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.

  3. 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!

  4. 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.

  5. 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. ๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž 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!๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž๐Ÿ‘Ž

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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!"

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

  14. 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.

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

  16. 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.

  17. 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.

  18. 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 ๐Ÿ˜‰

  19. 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"

  20. 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

  21. 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

  22. 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.

  23. 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

  24. 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.

  25. 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.

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

  27. 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

  28. 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.

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