We Have No Idea Why
ฝัง
- เผยแพร่เมื่อ 28 ก.ย. 2022
- Check out our shiny new story-based merch at dftba.com/minuteearth
Most animals on earth are bioluminescent, but almost all of them live in the ocean - and scientists aren’t sure why.
LEARN MORE
**************
To learn more about this topic, start your googling with these keywords:
- Bioluminescence: the biochemical emission of light by living organisms such as fireflies and deep-sea fishes.
- Biofluorescence: The emission of previously absorbed light by fluorescent proteins in a living organism.
- Luciferin: an organic substance, present in luminescent organisms such as fireflies, that produces light when oxidized by the action of the enzyme luciferase.
SUPPORT MINUTEEARTH
**************************
If you like what we do, you can help us!:
- Become our patron: / minuteearth
- Share this video with your friends and family
- Leave us a comment (we read them!)
CREDITS
*********
Cameron Duke | Script Writer, Narrator and Director
Sarah Berman | Illustration, Video Editing and Animation
Aldo de Vos | Music
MinuteEarth is produced by Neptune Studios LLC
neptunestudios.info
OUR STAFF
************
Lizah van der Aart • Sarah Berman • Cameron Duke
Arcadi Garcia i Rius • David Goldenberg • Melissa Hayes
Alex Reich • Henry Reich • Peter Reich
Ever Salazar • Leonardo Souza • Kate Yoshida
OUR LINKS
************
Merch | dftba.com/minuteearth
MinuteEarth Explains Book | minuteearth.com/books
TH-cam | / minuteearth
TikTok | / minuteearth
Twitter | / minuteearth
Instagram | / minute_earth
Facebook | / minuteearth
Website | minuteearth.com
Apple Podcasts| podcasts.apple.com/us/podcast...
REFERENCES
**************
Belkin, S. Bioluminescence Fundamentals and Applications in Biotechnology - Volume 1. Berlin Heidelberg, Springer-Verlag GmbH, 2014.Davis, Matthew P., et al. “Repeated and Widespread Evolution of Bioluminescence in Marine Fishes.” PLOS ONE, vol. 11, no. 6, 8 June 2016, p. e0155154, doi.org/10.1371/journal.pone....
Delroisse, Jérôme, et al. “Leaving the Dark Side? Insights into the Evolution of Luciferases.” Frontiers in Marine Science, vol. 8, 30 June 2021, doi.org/10.3389/fmars.2021.67...
Griffiths, Mansel W. “ATP BIOLUMINESCENCE | Application in Hygiene Monitoring.” Encyclopedia of Food Microbiology, 1999, pp. 94-101, doi.org/10.1006/rwfm.1999.0085
Haddock, Steven. Senior Scientist, Monterrey Bay Aquarium - Personal Communication.
Hellinger, Jens, et al. “The Flashlight Fish Anomalops Katoptron Uses Bioluminescent Light to Detect Prey in the Dark.” PLOS ONE, vol. 12, no. 2, 8 Feb. 2017, p. e0170489, doi.org/10.1371/journal.pone....
Marek, Paul, et al. “Bioluminescent Aposematism in Millipedes.” Current Biology, vol. 21, no. 18, Sept. 2011, pp. R680-R681, doi.org/10.1016/j.cub.2011.08...
Martini, Séverine, et al. “Distribution and Quantification of Bioluminescence as an Ecological Trait in the Deep Sea Benthos.” Scientific Reports, vol. 9, no. 1, 10 Oct. 2019, doi.org/10.1038/s41598-019-50...
Martini, Séverine, and Steven H. D. Haddock. “Quantification of Bioluminescence from the Surface to the Deep Sea Demonstrates Its Predominance as an Ecological Trait.” Scientific Reports, vol. 7, no. 1, 4 Apr. 2017, doi.org/10.1038/srep45750
Mofford, David M., et al. “Latent Luciferase Activity in the Fruit Fly Revealed by a Synthetic Luciferin.” Proceedings of the National Academy of Sciences, vol. 111, no. 12, 10 Mar. 2014, pp. 4443-4448, doi.org/10.1073/pnas.1319300111
Yirka, Bob. “Researchers Seek to Explain Why There Are so Few Land Dwelling Bioluminescent Species.” Phys.org, Phys.org, 23 Aug. 2012, phys.org/news/2012-08-biolumi... - วิทยาศาสตร์และเทคโนโลยี
![[LIVE] : ONE ลุมพินี 66 วันนี้!! คู่เอก "ก้องชัย vs อัคราม"](http://i.ytimg.com/vi/j4uI5Uy8mWQ/mqdefault.jpg)
I'm no expert, so it's very possible I'm missing something, but it seems like there'd be a significant difference between nocturnal/polar darkness levels and deep-sea darkness levels. Most nocturnal animals can adapt to lower light levels by simply improving their night vision, but at some point, that'd probably start showing diminishing returns, and when you get deep enough in the ocean the level of darkness could be high enough that those sorts of adaptations wouldn't really work, forcing other approaches. That doesn't necessarily answer all of the problem (I assume I'm not the first person to think of that, after all) but it feels like it'd at least go a long way toward starting to explain the discrepancy, right?
There's definitely a difference between deep-sea darkness and the polar darkness, but one fascinating thing (in my opinon) that we didn't include in the video is that the rate of bioluminescent species is more or less consistent from the surface down to 3900 meters (which is how deep the authors of this paper surveyed: www.nature.com/articles/srep45750#:~:text=Our%20study%20quantifies%20that%2076,a%203%2C900%2Dmeter%20depth%20range) So many of bioluminescent ocean species experience both day and night (or live in a somewhat twilight-zone depth)
Hey they answered
Good point, but what about cave dwellers some live in places without any light
@@MinuteEarth Well if bioluminescence does preferentially evolve in the depths, that might provide an easy 'in' for the descendants of a bioluminescent species to return to the surface and have the benefits of bioluminescence there too, even if the benefits are weaker. However, this still doesn't make any sense under the additional context of places like Lake Baikal lacking bioluminescence.
I guess there's an interesting question that might help answer the mystery: Has any species devolved bioluminescence? If so, that might be illuminating, or maybe we'll still be left in the dark.
@@MinuteEarth what are the chemical/evolutionary precursors to bioluminescence? Or basically, how did it come to be/what led up to it?
My guess is it has to do with the poupulation density of places. The ocean is vast and I’d imagine it could be hard to find anything in the deeper sections of it without the bioluminescence. However, in land you normally can find mates and prey without traveling too far. Not only that, but prey having bioluminescence could make them much more noticeable in more populated areas while it may be safer in the oceanic depths where predators are scarce
Oooo I like that theory! To try and add to it, I’m thinking the line of sight thing has a lot to do with it. You could see something glowing in the water from any direction, but on land that’s not the case. So I’m thinking bioluminescence wouldn’t work often enough on land to make it a useful adaptation. Besides some very specific scenarios, like in caves with the glow worms or flying around like the bugs
@@sackywacky I'll add to those great ideas - the ocean is also DARK. Not dim, like a moonless night but pitch black. A tiny amount of light would go a long way in the depths; whereas on the surface, it would barely hold a candle to the stars, let alone any phase of the moon.
I also like this idea and I think at least a small factor is there is simply a lot more light on the surface to work with, for example even at night animals like cats can still see in what we might consider to be pitch black or it could just be as simple as having a stronger sense of smell or sound is overall more effective up here and most animals just don't need to rely on light.
Also, in the ocean a source of light only means bioluminescence, while on land there may be other sources of light "competing" for attention. You can't see stars in the ocean, obviously...
I love this comment thread! So many great ideas, would love to see a follow up vid or something!
Well, the part of the animal that glows must be transparent to light, so maybe land animals need to prioritize protection against the sun's UV rays, or protection from other things, like hair or scales. It seems that most glowing bits are mucus membranes or soft tissue, which is much more vulnerable on land. Just a guess, and doesn't explain the darkness of lakes.
Thats what i was thinking
@@PulseCodeMusic Yep, very first thing that came to mind. Land creatures have needed tough skin for sun protection and moisture retention ever since the first squishy little fish crawled onto the beach. Additionally, our branch of the evolutionary tree has to support our own weight without buoyancy, so thin, delicate sacks of bacteria aren't an option. And our blood is opaque, whereas fireflies have hemolymph. And mammals and birds have hair and feathers.
It's my understanding that many bioluminescent creatures spend the day deep underwater and rise to the surface only at night. Lakes and rivers are relatively bright environments and moving between water bodies usually involves getting exposed to the elements somehow whether it's through a shallow stream or in the claws of a bird. Deep lakes are much smaller than the oceans, and not as long lasting. Usually volcanic or tectonic, isolated from the surface by lack of currents. Caves even more so...
I agree most with this idea
Bioluminescent tattoos are a thing so you don't need to be transparent.
@@MrNeilandio you mean tattoos that react with UV light? Those are not bioluminescet
My best guess is that this has to do with all animals actually emitting light all the time, not in the visible, but in the infrared spectrum. Many insects, reptiles, and some mammals evolved to be able to detect IR light because air (but NOT water!) is transparent to it. So even in the dark, organisms on land have no need to develop bioluminescence: air allows them to be already detectable!
That means they are bioluminescent then just on a different level then we can naturally appreciate.
I vote for the sea raves idea !
th-cam.com/video/oWqAf4eex14/w-d-xo.html
Crab Rave half-canon?
It might be just a simple question of geometry. The ocean has one more dimension to get lost in, while any organism on land can efficiently search mates in only two dimensions. (Height in air doesn't count, because nothing can stay at altitude forever) Thus not enough benefit from being glowy.
Yep I was thinking the same thing.
Land is 2d, unless of course you can fly and you are also very tiny, like a fireflight..
Related: th-cam.com/video/iH2kATv49rc/w-d-xo.html (random walks on 2D and 3D are fundamentally different)
This still fails to explain why there aren't any bioluminescent organisms in deep, freshwater lakes that have the same kinds of conditions, though.
@@hexwolfi Please read my comment again.
@@manuvillada5697 Firelight? have you been watching Arcane?
I don't think you properly ruled out darkness as a major reason. Land is always being lit up, even during a new moon the stars still give off light which animals can adapt to using. The ocean is completely dark after a certain depth though making the small amount of light gained from bioluminescence worth much more. Unless there are just as many bioluminescent ocean creatures in the low light levels of the ocean as the no light levels, then it's still a mystery.
Many ocean species of bioluminescent creatures live around the twilight zone, which means they constantly switch between dark, dim and sometimes even slightly light when it is daytime
There are cave fish species who reverse evolved their eyes to nonexistent because of how dark their environment is. And yes, somewhere in the comments authors of the vid mentioned that there is same amount of bioluminescent creatures on the surface and in deep darkness.
Practically 100% of bioluminescent creatures live in the midnight zone, and if you watch your blue planet 1 and 2 in each one's episode about the deep they actually talk about bioluminescence and what the various creatures are using it for. So this person is just wrong when they say we don't know why the majority of creatures are bioluminescent in the ocean.
If my memory serves we have discovered far more species that live in complete darkness for 100% of their lifetime (unless a human submersible with headlights finds them) then there are in all other parts of the planet combined
@@the_undead Your memomery fails you. Most of species worldwide are found in a few hotzones of biodiversity, namely tropical rainforests and for much shorter time (geologically speaking) coral reefs. The vastness of the ocean is actually mostly empty due to lack of developed and complex food webs.
Also I'm not counting microorganisms, since we still discovered less than a fraction of those no matter where we look.
I think necessity plays an important role. To find a mate on land animals use flashy colours or pheromones but smelling is much more difficult in the ocean, sight is useless at great depths and taste is useless in general.
Meaning animals need to specialise their hearing (echolocation), sight or create a new sense (electroreception).
Using bioluminescence allows you to use your existing senses without upgrading them to their extremes. It is also very versatile such as finding mates or prey and even as a defense. This versatility means that many pressures can lead you down this path explaining in part why they love it so much.
Smelling is actually much easier in the ocean. Chemicals can remain suspended in water much better than in air.
Smelling is actually much easier in the ocean than it is on land because currents can you usually keep assent much more concentrated for much longer distances than wind, site is absolutely useful in the dark because of all the bioluminescence that the vast majority of creatures down there use
Also I have no idea why this person said we don't know why so many creatures in the ocean use bioluminescence (or however they worded it) because with the release of blue planet 1 in the early 2000s, it was actually known why so many different species used it, some for hunting others for communication and still more for distracting predators were the main three reasons.
@@wasd____ Smelling isn't about 'suspending particles'. Its about using volatile compounds that evaporate at room temperatures and disperse in the air.
This mechanism wouldn't work in water. The only molecules that remain suspended in water are the ones that are soluble in water or have similar density to water. (Otherwise they would float or sink quickly).
I also made a similar comment earlier.
Its not that land animals cannot evolve bioluminescence.
The main issue is that land animals have a better alternative, that is smell.
Smell is more efficient, takes less energy (than bioluminescence- light production is every energy intensive), and smell can be used for multiple other purposes.
That also explains why we have flowers instead of bioluminescent plants to attract insects for pollination. (Although pretty much every insect is attracted to light).
We humans are visual creatures so we take smell for granted. Nearly 90% land species use smell as their primary sense. Including dogs and other non-primate mammals.
Despite sight being such an important sense, the fact that overwhelming terrestrial species use smell as the primary sense, speaks volumes about how effective smell is.
Ocean creatures have evolved various strategies to combat lack of smell. Bioluminescence, echo-location, are just some examples.
@@mahadevparmekar2565 if smell is so worthless in the ocean then why the hell do sharks rely on it about as much as a lot of land predators?
Also there is at least one species of fish down in the deep that does use scent for something, female angler fish release sense into the water that male angler fish can detect with what is effectively their nose that they used to track down and find a female of which they permanently attach themselves so they provide the female with sperm and the female provides the male with sustenance. So if sent is so worthless down there like you're claiming then why can angler fish use it to find mates from potentially over a mile away
I always thought it evolved as a camouflage method, like how hatchetfish use it today. That would kind of rule it out for mammals and reptiles, as they wouldn't be able to make much use of it due to a lack of predation from below.
Bioluminescence is fascinating to me, as an icthyologist, and I love reading about cool bioluminescent fish. My favorite examples are probably the Malacosteus (stoplight loosejaws) that use red bioluminescence to detect prey. Many deep sea fish are red (and cant see red) since red light doesn't penetrate to their depth. Stoplight loosejaws basically shine an invisible flashlight on their pray, which is awesome
Do also note that the land animals with biolumi are insects who adapt rather fast. And seems like a good portion of then can fly and spread vast distances.
I suppose to find similar animals on land, if you’re walking you preferably want other ways to leave/track traces, and smell/scent seems easier than light (to find mates) which may draw unnecessary attention.
But usually you are in similar ecosystem that isn’t as vast in 3 dimensions as the ocean.
That explains the caves thing, and the explanation above (and with the moon I guess) explains the no light on land thing.
Firefly:*Doesn't live in the ocean*
MinuteEarth:"I can't believe you've done this"
By no means am I a chemist. But the first question that pops into my mind when I heard the premise of the question was, "what's the chemical makeup of the bioluminescence both the land and the sea"? Is the bioluminescence similar or vastly divergent?
A chemist wouldn’t be able to answer this, this is more known by biologists ;) but what you’re looking for is called luficerin. It’s a class of proteins that produce light reactions. By oxidation get it (literally by making it react with oxygen) you create light. The oxidation is as far as I know, always done using ATP as an energy source. ATP is a very common form of energy, made by mitochondria that all animals and plants have within their cells.
Maybe it also has something to do with how light travels through water. Light can reach a lot farther in air than in water, so a creature that can generate light on its own can attract whatever it wants to while not broadcasting its existence to possibly unwanted beings.
Yeah! Negative result videos! I have a soft spot for "yup, we just don't really know, but it's super interesting nonetheless"
It might be that the bar for evolving bioluminescence is lower in the ocean than on land. There are several species of marine bacteria that bioluminesce (such as Vibrio harveyi). For a marine animal to evolve bioluminescence, all it has to do is culture these bacteria somewhere in it's body. Since these bacteria are only found in marine environments, non-marine creatures can't form a symbiosis with them, and therefore, must evolve bioluminescence on their own.
This was originally a response to a post, but I figured it would get more visibility as its own comment.
That only shifts the question. Now the question becomes, why aren't there bioluminescent bacteria on land or in fresh water?
@@jamesdinius7769 that is a very good question. There are lots of organisms that never made the shift to fresh water or land (echinoderms come to mind, but there are many others). It's possible that there's a common thread between these disparate groups keeping them from evolving freshwater and land forms. Or perhaps they just need more time to evolve. Regardless, more research is needed on the subject.
I feel like there’s a difference between the darkness at the bottom of the ocean than the darkness at night with the moon, stars and human made light
For diurnal animals like primates (including humans) the dark of the night on a new moon in a pre-agricultural world and pitch black, which the bottom of the ocean would be, is essentially the same.
Not to mention the dark in the oceans is always dark, whereas on the surface is partially dark
Nowhere near equivalent, maybe for us, but most of the animals kingdom has much better night vision and star light is pretty effective if you have a proper tapetum in the eye to help amplify, at least allowing you to maneuver. The ocean is absolute darkness, no light at all penetrates the depths.
@@HercadosP caves
@@alex_zetsu But a new moon only occurs about once a month, so maybe that's not really as comparable a disadvantage over the course of multiple days?
1) It's okay to not have all the answers.
2) Thank you for a video featuring one of my favorite words/phenomena, bioluminescence.
It is okay to not have all the answers but when the answer has been known since like 2001 (whenever the first blue planet was released) if you're trying to make a comprehensive guide you should know.
I don't know much about why fireflies bioluminesce because that's not a subject that interests me but practically 100% of oceanic creatures that bioluminesce either spend 100% of their lives or the vast majority of their lives in the deep where there is no natural light, and the reason so much of it is blue is because the ocean attenuates blue light the least so it can carry the farthest, there is one creature I am aware of that uses red bioluminescence because no creature except for that one that deep can see red light at all, and a lot of creatures are bright red because that makes them practically invisible except to this one fish which I forget what it's called cuz it's been quite a while since I last watched Blue planet.
"It's ok to not have all the answers"
What makes you think anyone, let alone a popular channel on the internet, would need YOUR personal approval for whether or not something is ok? What a dumb comment.
@@j.r.8176 give you I have with this comment is not the same as yours, some of the answers have literally been known since blue planet's release in 2001. They have an entire 40 minute episode dedicated on creatures of the deep and they provide a reason for at least some of the bioluminescence displayed on the creatures they showcase, not all of them but more than enough for this video to be a little bit more than pure speculation
@@j.r.8176 wow, nobody needs my approval. But it sounds like someone could use more fiber...
I am outraged that this video titled "we have no idea why" has not given me a definitive answer to this question.
Maybe it is because of a funding issue? The devs haven't rolled out the mod to everyone yet as short qualified programmers. They should open source it.
i agree
Thanks for brightening up my day :)
I’m not anywhere near being a professional in any of the areas of bioluminescence, evolution, or bodies of water, but a lot of animals in these really deep lakes like eels and catfish have almost like a sixth electrical sense that can detect things in the murky depths and I’d like to think that probably works better for them in freshwater as opposed to the ocean if not only for the fact that it doesn’t work as far as bioluminescence (especially with how cloudy freshwater is in my experience)
Perhaps because air allows light to travel farther and give away your position from farther, whereas water does not.
Also, if almost everything can swim, you're likely to be attacked from below in the ocean, rather than just behind you.
If you glow, your light helps hide the shadow you cast from the light above you. Making you harder to see from below.
but then if something is approaching from above it gives you away.
Land animals have developed different senses for nighttime visibility: the reflective tapetum lucidum layer in a cat's eyes and also of other eyes is one of the evolutions that helps these animals see better in the dark by multiplying dim light to locate prey.
Sugar gliders and other animals have gigantic eyes to also see better in the dark, like tarsiers and other animals.
Owls have large eyes, but also have cone - shaped areas around the eyes to gather a lot more sound to be picked up by their unequal ears better.
And of course bats have incredible echolocation to find their way and their prey in the dark.
So, many crepuscular and nocturnal land animals do not need bioluminescence to find each other or to hunt their prey.
I think it is harder to develop night vision in deep water because less UV/IR light exists there. Also, unlike above water it is permanent darkness below water so they can't wait until daytime to get light.
Why visible light is harder to have night vision or can't have?
We can see at dim starlight but only visible light. and plus visible light is the best light in the ocean water absorbs infared and uv easily
But not much in visible light.
And evolution would force them to use visible light because thats the only light there..
One thing it could be is that land animals may change from diurnal to nocturnal in a shorter amount of time, based on things like which other nocturnal animals are competing for food, meaning they wouldn't be nocturnal long enough to evolve bioluminescence.
Thanks for the video
This always make my day alot better
And as they say " you learn something every day " and you make that learning possible
Maybe it’s because bioluminescence requires/benefits greatly from transparent/translucent skin, and it’s easier to have that if you body is made more out of water than land creatures.
these bugs be like: UNLIMITED POWER!!!!!!!!!!!!!!!!!!!!!!!!!!
Maybe it isn't just salt but some sort of microorganism that has a mutual relationship with many sea creatures. These organisms evolved and depend on saltwater to live which is why it only appears in salty water but adding salt to water changes nothing. If the microorganisms weren't there to begin with or are usable for freshwater creatures it wouldn't matter.
It would be like how termites have special gut bacteria to break down wood that is different from our own gut bacteria. If humans started eating wood unless we somehow came into contact with that bacteria and it evolved for a mutual relationship we still wouldn't be able to eat wood. If we are in an environment like a desert that doesn't support wood and so that bacteria it would be impossible for that exposure to ever occur.
en.wikipedia.org/wiki/Aliivibrio_fischeri
@@bjsmith89 exactly thank you for the link
Are we able to check for bioluminescence in fossile records? Would it even be possible that humans hunted surface bioluminescent creatures to extinction? If we can do it to megafauna, maybe glowing creatures were useful or cool enough to warrant hunting them over others.
A cool exploration. It's even trippier when you consider that light is something far broader than what is only visible; that the significance of "visible light" is that it's what moves through water the BEST.
I think it has to do with the water obstructing light. Since light travels so well through air, the sun, moon and stars provide more than enough. It's also possible that if you evolve bioluminescence in air, it makes you an obvious target from much further away.
I don't know how to explain the freshwater disparity, unless light travels easier through fresh water than salt water, in which case, glowing in Lake Baikal would make you a target from a mile away while the salts in the ocean would obscure the light completely from only a few meters.
It's also possible that it didn't evolve independently in different fish species, but instead, the evolutionary changes simply determine whether the genes are expressed or dormant, meaning freshwater fish would be genetically cut off.
Huh I'm confused. I remember reading / hearing that the reason why bioluminecense exist is because it's a defense mechanism.
When predator fishes look for pray, they usually look for them from a greater depth, and they are actually looking for the shadow of the smaller fishes created by the light from the sun(above the sea) . So a bioluminecensent fish would look invisibile to those hunters, especially when they are more at a shallow level
Perhaps it was outdated information? How long ago did you read/hear it?
That is one of the ways that bioluminescence is used, but far from the only way. Some animals eject a cloud of glowing goo when they are attacked, in an effort to distract and temporarily blind them. Can also force the attacker to break off pursuit, for fear of their own predators identifying them covered in glowy goo.
All species of Angler Fish, on the other hand, use bioluminescence to lure prey into reach of their jaws. It's a great way for them to conserve energy, since the food will literally swim up to you. Other predatory fish have glow spots under their eyes, almost like headlights, that give off light in specific wavelengths other fish can't see. Their prey is clearly visible to them, but other creatures, including the target, can't see.
There isn't a singular answer as to why.
I know that's what is believed for a certain species of squid i think. It shows it's bioluminescent side downwards so that it blends in with the bright surface. Not sure how deep it lives tho
My guess is camouflage. Most oceanic bio-luminescence is used for backshading, lighting up the bottom side just slightly to remove the shadow.
This doesn't explain the lack of bio-luminescence in freshwater deep lakes though.
Probably just the fact that lakes are very ephemeral on the geologic timescale. Only lakes which are part of large tectonic features tend to last long enough for fancy stuff to evolve. Maybe bioluminescence takes enough time to evolve (at least a few tens of millions of years) that lakes just don't stick around for long enough, but can be evolved quick enough (less than a few hundred million years) that it can pop up in many lineages of oceanic life.
my guess would be that since many marine species use bioluminescent algae and bacteria, which don't live on land, it's harder for land animals to access them for a symbiotic relationship
Thank you, that was fascinating. I didn't realise there was so much to that question, which makes me adore the people who made the observations and started asking these things.
I think it's a combination of things which makes it hard to determine any specific factor.
Kinda this
I mean... It seems easier to get a symbiont like that in the water, to me. Think about it: a bioluminescent bacteria can be found in the ocean with some ease... but these bacteria don't go about floating in the sky, probably something to do with UV being too much. So, it is harder to evolve such a character on land than on the ocean since you would mainly aquire the symbiont vertically (from the mother). In the water, you can just ramdomly grab one from the current... At least, that's how I see it.
I think it has something to do with the abundance of certain elements required for bioluminescence in the diets of terrestrial as well as aquatic animals. We notice that much of the animals which are strictly non aquatic are actually living in environments which is moist. Besides one thing which we need to count for terrestrial organisms not having this adaptation is that, on land even though it is dark, the moon's glow, and background light is present, to which the vision can adapt.(Maybe it's easier to develop modifying vision than bioluminescence). Another thing which must be considered that terrestrial organisms do not spemd the day throughout perpetual darkness unlike deep-sea animals, the solar light may inhibit any mutationwhich can express bioluminescence.
My two-bit theory: it's because vision works better in air. The idea that you can see farther in the ocean because there are no trees is silly, the limiting factors are the transparency of the medium and the difference in index of refraction between the medium and the lens of the eye. Air scatters light less than water, suspends particles less easily, and the larger difference in index of refraction from solid lens materials means an animal's lens doesn't have to deform as much to focus nimbly. This makes producing light in air more of a liability, as things will not only see the light, but see exactly what and where you are. Lake baikal is an interesting single exception, but I don't think it can be taken as significant. After all, I'm sure there are many things which are common in oceans/deeps in general which do not exist in lake baikal.
Thanks. I don't know all the mechanisms behind bioluminescence, but I wonder if lack of certain elements or minerals (through, for instance, diet) might play a role in explaining this. Some areas like caves or lakes can be quite isolated, even containing unique species. They could also (I suppose) lack some necessary ingredient(s) to create bioluminescence. Or it could be because of the relative sizes and/or number of species within such regions. Just a thought. Though I can't imagine such ideas not having been looked into already, stranger things have happened. tavi.
Darkness on land and darkness past 1000m depth in the ocean are very different. Other than a few cave systems, it never gets so dark that a noctural animal can't see just fine.
And if I recall, deep cave dwellers, while not bioluminescent, have simply adapted in other ways to the dark (such as keen smell or echolocation).
This was fun! I love the graphics and narration. I wish these were an hour long and not just a minute!
0:50 "PERHAPS THEY LIGHT UP BECAUSE IT'S DARK"
What a genius idea...
It might be something like an evolutionary version of a file format. If several species you're competing/surviving with already communicate with bioluminescence, there's going to be pressure to use it as well.
It could also be an exponential phenomenon where 1 glowing cyanobacterium 8million years ago diversified and brought the trait into a bunch of other species. (But you still need to explain how every family developed it, because a cyanobacterium ancestor wouldn't have given it to a fish without all fish getting it, nor does it explain the different colors because while blue is most common some predators use red instead)
Did you list of reasons sea creatures evolved it and land did not [as much] consider the amount of time that an animal is in the dark? Most land animals have a greater percentage of time where they have to deal with either full daylight or at least some daylight. Those deep sea animals spend most times in very dark areas or at least at nighttime levels of darkness.
There were very few lightning bugs in my yard this summer. A huge Buccees was built in one direction, and another large convenience store/truck stop in the other, with an extension to our subdivision that cut down a substantial wooded area.
The presence of the Burj Khalifa on the bottom of Lake Baikal probably provides enough illumination by itself to make bioluminescence unnecessary there.
Many mammalian animals evolve colours to camouflage with the their environment (or against their prey, see tigers for example orange to us humans with tri-color vision but hidden to deer), bioluminescence would run against camouflage making both predator and prey incredibly noticeable to each other. If there were few predators biolume could possibly develop to attract a mate similar to how theres many birds that are colourful or have ornamentation to attract mates
I imagine evolving colour camouflage and colour mating displays is a lot quicker, easier and no less effective in sunlight than evolving bioluminescence. And evolution always takes the path of least resistance. In the dark ocean where most animals are translucent, colour is useless, but bioluminescence can do the same job. Caves and lakes were occupied far more recently, you see in caves the tendency for animals to lose their colour and their eyes. I guess in the short term losing the eyes (redistributing the resources needed for making eyes) is beneficial but in the long term, once your eyes are gone you're not going to evolve bioluminescence, are you?
Hmm, throwing ideas out there, but the entire point of bioluminescence is generally communication of some kind right?
I wonder if on land, sound is just easier to adapt for communication than light, so that become the default choice.
I was thinking like that. Sound is much harder to create underwater, it needs a specialized organ, like in mammals. So visual communication is the default for smaller animals, like colors and patterns and light. But it must be a combination of things that supports the need and evolution.
On the other hand, even a cricket can make noise on land, so not as much pressure for evolving light. And those that have light are nocturnal animals and use it for some kind of communication eg. lure, don't eat me, I'm here, etc.
Maybe its because a lot of land creatures are fluffy, or covered in feathers, which would be hard to glow through. And the ones that arent might not often be ones that could benefit from lighting up. Like diurnal reptiles, amphibians that live in shallow water, ambush predators, prey animals that need to hide, or any creature that relys on camoflage in any way to survive. Forest dwelling creatures too, as mentioned in the video. Maybe the fish in lakes dont evolve biolumenessance because lake water is often at least a bit murky, so the glow just wouldn't do much. And even if the water is crystal clear, they aren't always at the bottom, deepest part of the lake. Being glowy when their close to the surface might just get them eaten.
Time to make the sequel to owls that have spotlights on their chests like police helicopters
So what’s the paradox?
What causes bioluminescence in all those animals? Is it all the same or are there many ways to be bioluminescent?
Lots of things! Generally, it's a chemical reaction between molecules called luciferin and luciferase, but here's the really weird thing about these chemicals - these words are pretty much just general terms for the molecule the animals use. The exact chemicals will be different depending on what animals you are looking at (ex. 2 different fish or a firefly versus a fish). Many animals outsource their luminescence, like anglerfish, which cover their lures in luminescent bacteria.
I think its cheaper to just smell in air environment (the smell spreads faster on air than water) than making light.
The thing with fireflies is they're mildly toxic, so nothing really eats them other than other species of predatory fireflies that don't seem to be bothered by the irritating chemical. Because of that, producing light doesn't really leave them that open to predation. The possible disadvantage is minimized because they apparently don't taste good to any potential predator.
Other than that, it's likely something to do with biochemistry. On land, it's only invertebrates that have it. So it could be a limitation on the enzymes or protein structures needed to make it work. Something like a fast enough metabolism may break down compounds before they could be made available for something useful for producing light instead.
Land animals lighting up under UV, is it also considered bioluminescence? 🤔
Good question! Lighting up under UV light is a phenomenon called biofluorescence. An animal is biofluorescent when it absorbs light from a source and re-radiates it in some way. Bioluminescence is when some sort of chemical reaction generates the light we see. Lots of animals are biofluorescent, and many are both biofluorescent and bioluminescent!
@@MinuteEarth would a chemical process that creates light and is powered by light be both then? as opposed to directly storing and using the sun light, more like turning it into your own light
Darkness in water, is VERY different, than darkness in the air. Your hypothesis is not correct. For hunting at night, land animals have developed larger eyes, that absorb more light. And can draw more ambient light out of water
But animals in the oceans can't draw light the same way, because light is refracted in water. So a strong pulse of light helps draw prey, or repel danger.
Please follow up with this hypothesis.
The lab that was testing the hypothesis of Sea raves sounds like a pretty fun lab to be in.
Couldn’t help but bop to this 7/8 time signature music! More videos should have this kinda stuff
appart from the non complete darkness of the land and the much lower population density of the sea, could be related to how only a small part of the light spectrum penetrates much into the sea while on land all are available and we see plants and animal use light further into the ultraviolet that can have a similar function without revealing their position to predators
My 2 hypothesis is that there is bioluminescent plankton and fishes gained the ability from either eating the plankton or eating the thing that's eating the plankton. Similar to how our cells gained a mitochondria by eating a mitochondria. And then more fishes continue to eat other fishes who gained the bioluminescent ability and just spread like that.
The other one being that it's very disadvangeous for land animals to have bioluminescence as if either prey or predator has it, they would either be eaten or starve to death. Glowing at night makes it easy for predator to see them and predator glowing at night makes it easier for prey to see them.
It might be heat too. It’s easy to cool down some light source down in water
Animals on the surface or land mass of earth have lots of night time light. Even with no moon and no interference from man made light, the stars alone provide an amazing amount of light. It’s in the ocean where it gets truly dark.
I feel like Starlight must have something to do with this. When it's dark on land, you still have the starlight. Animals with eyes that are good at collecting light, like owls, can see not too terribly in the Starlight
Thanks!
Every time i see a firefly i feel like I'm in a magic world
It have something to do with how vulnerable it makes you on land because light travels further and faster through air than it does in water
One small correction: The medium doesn't matter so much to the speed of light. It's still hundreds of miles per second. But you're correct about the travel distance.
Thank you
I love the long season of fire flies in the middle of summer and the shorter season of glowworms as the days get colder.
0:46 i almost didn't even think the Chinchou was out of place...
The moment I saw all the water creatures next to the firefly was the moment I knew why it’s special
Not a marine biologist, or any biologist for that matter, but maybe the prevalence of a trait makes it more beneficial to mimic, like how some non-venomous snakes appear similar to venomous snakes while saving on the energy required to make venom. Maybe being around many other bioluminescent animals brings benefits to being bioluminescent yourself, and since there aren't currently enough luminescent species on land or in lakes it doesn't benefit to stand out in that way.
I've had a bioluminescent rabbit!
My father was a genetic engineer and a research project manager for the big scary biotech company that rhymes with Donfanto, and they cut in genetics from octopi with their introduced snippets of other DNA when adding traits into crops, so they could see from the resulting phenotype if the new genetics were activated (if it glows, it's a-go!). They did it with mammals while they were developing the technique.
So, yeah, I got ahold of genetically engineered cotton, corn, and glowing bunnies as a child since my dad had a *lot* of patents.
One point of differention in the darkness category is the surrounding habitat: In deep sea, darkness is everywhere and constant in a wide area (/volume). Emitting light is an advantage here.
Compared to the three given examples, where darkness is temporary (on varying time scales) close to a given location: Cave dwellers and night active animals create an advantage by using darkness, thereby evading many species adapted to daylight. This is only possible because of the abundance of light in the vicinity. Illuminating themself is detrimental to that 'strategy'.
Predators/prey need complex organs to be effective in daylight and darkness and most species developed specializing into one. It's not efficient to grow features with limited benefit, which creates the niche bats/owls/etc. use.
Which might also serve as an explanation for the polar regions with long term darkness. The necessary organs would be useful throughout those dark periods, but not the full year. Additionally their redundant with other strategies (like living in huge groups in otherwise scarcely populated areas).
My theory is because of scent. The ocean dissipates smells quickly but scent lingers in air longer.
EXACTLY the kind of video I subscribed for
Just wagering a theory, but I just don't think it's safe to be that conspicuous on land. From what I understand, there are other species of insects who take advantage of fireflies and their mating habits (which is why they display). I also don't believe adaptations have to serve one or two functions. There's a reason why it functions for them and the other terrestrial organisms that also use bioluminescence. Heck, there are fungi that do it and they don't have eyes. We have to admit there will exists limitations to our understanding, especially when it comes to adaptation, mutation & evolution.
It's definitely gonna be a combination of all the presented options and at least one factor we haven't considered yet.
I wonder, could the availability of light producing animals increase the chance that a non-light producing animal would evolve the trait? Consuming bio-matter can lead to the transfer of genetic material that influence those rare mutations that move evolution along. The more bioluminescent things you consume, the more likely your next minor mutation might be influenced by it.
I love this kind of videos that make me asking about the nature and the existence 👌👍
I may be missing something, but could it be because of the relations between the predator and the prey? Normally a predator wants to stay hidden and so does the prey. Perhaps the only species that managed to evolve bioluminescence are the ones that are either at the bottom of the food chain or reproduce really fast? That could explain why no big creatures evolved to produce their own light. Another theory could be that echolocation and better eyesight are just more useful on land simply for the fact that there's a greater amount of obstacles obstructing movement and vision? An animal won't be able to move as freely on land as a fish in the sea in an open space. Anyway this is all really intriguing!
edit: ah it seems other comments mentioned something along those lines already :)
The hidden Chinchou made me really happy.
The explanation that I heard that I really like is that it’s a thing because predator fish with think twice about eating pray if it can glow because they it will stick out like a swore thumb and be picking off next.
This idea works well in the ocean because it’s all mostly out in the open making it easy to spot something that can’t camouflage it’s self, but not so well on land or in swallower waters like rivers because there’s a lot more place to hide and the ocean naturally gets darker the deeper you go down where as on land it only gets dark at night when a lot of animals aren’t even actively walking around.
On land the comparison would be if an animal could evolve to have a defense mechanism like a paint ball or dye pack where they would mark a predator and run away in a smoke screen totally rendering camouflage useless
Fish with electric organs can create a field around them to sense what's near them in muddy water. Or give you a good shock. So cool.
That's not a paradox, it's just an unknown
I personally think it’s because of the types of animals in the ocean. It isn’t mammals or amphibians or reptiles (their ocean counterparts) being bioluminescent. We really only see large quantities of bioluminescent fish, dunno the kingdom for eels or octopuses, and bugs. Maybe the different types of genetic make up or biological structure make bioluminescence more possible in these types of animals. And side note for animals, being covered in fur likely determined that we would not be bioluminescent.
I wonder if a lot of things are bioluminescent on land, but in wavelengths that we don’t see. We are good at seeing the wavelengths that pass through water, so we’d notice the ocean critters doing it, but might not see the glowing birds or whatever if it is out of our spectrum.
It's not like we don't have tools that can detect that. I mean, everything warmblooded _does_ glow in infrared, because that's what heat is.
And before you should "eureka," the problem with that is that no creature can see the same wavelengths their body produces-if they could, they'd never see anything else.
@Daniel Pepple So do most flowers but fluorescence isn't the same as luminescence
hey, just a question, are the stats at the start in terms of biomass or in terms of number of species?
Nice accurate no click bait thumbnail
I like that Chinchou got slipped in there 0:47
Maybe bioluminiscence is handy when most other animals around you use it. The animals then have no idea if the light comes from their prey or even bigger predator. It may be different if there are no bioluminescent species around. It draws attention and everyone knows that glowing stuff is their prey or their predator.
Fun fact, at least one species on land have evolved non-bio luminescence, and it started in a way that's almost unable to do under water.
Fire.
Well there _were_ bioluminescent mice, but the bioluminescent owls finished 'em off.
I once watched a documentary about angler fish which stated that they evolved bioluminescence because the deep ocean is so dark (way darker than the land ever gets) and so vast that they'd never find each other otherwise. Even with the built-in light bulb, once they've found a mate the male is permanently fused to the female because there's a significant likelihood they would never find another one.
So I think the question remains, what's different about fire flies to other land creatures? Also, in order to evolve something the right mutations have to occur to be able to select for it. Bioluminescence isn't as simple as say continually selecting shorter tails until they disappear, what was the precursor to it and how likely is that mutation likely to occur in bats or penguins for example.
Love that they added a Chinchou ( a Pokémon ) in the top right corner 0:47
I would guess that it has to do with how far light travels in water vs air and how that alerts aerial predators
For anyone who missed the first few minutes: the title initially said "The Mystery of Bioluminescence
Why do you think others missed that?
@@lynnrolaf7422 well they changed it
They'll change it again in a day or two
Just from speculation, land dwelling animals being luminous at night would definitely mean ending up as dinner for predators that have adapted low light eye sight. So that could be explained away pretty easily.
75% of animals in the ocean making light sounds way too high, are you sure about that figure?