Why Are Scorpions Fluorescent?

Under UV light, almost all species of scorpions glow a bright green color, but why? Thanks to Capital One Shopping for sponsoring a portion of this video! Avoid Paying Full Price. Get Capital One Shopping for free using this link: capitaloneshopping.com/verita...

A huge thanks to Prof. Carl Kloock for the interview and taking us scorpion hunting at the Panorama Vista Preserve. panoramavista.org/

Zwicky, K. T. (1968). A light response in the tail of Urodacus, a scorpion. Life Sciences, 7(6), 257-262. -- ve42.co/Zwicky1968

Kloock, C. T. (2005). Aerial insects avoid fluorescing scorpions. Euscorpius, 2005(21), 1-7. -- ve42.co/Kloock2005

Gaffin, D. D., Bumm, L. A., Taylor, M. S., Popokina, N. V., & Mann, S. (2012). Scorpion fluorescence and reaction to light. Animal Behaviour, 83(2), 429-436. -- ve42.co/Gaffin2012

Kloock, C. T., Kubli, A., & Reynolds, R. (2010). Ultraviolet light detection: a function of scorpion fluorescence. The Journal of Arachnology, 38(3), 441-445. -- ve42.co/Kloock2012

Kloock, C. T. (2009). Reducing scorpion fluorescence via prolonged exposure to ultraviolet light. The Journal of Arachnology, 37(3), 368-370. -- ve42.co/Kloock2009


Written by Derek Muller, Emily Zhang, Petr Lebedev
Animation by Iván Tello
Filmed by Derek Muller and Emily Zhang
Edited by Brian Kim
Additional video supplied by Getty Images
Music from Epidemic Sound epidemicsound.com
And "Sneaky Snitch" by Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
Produced by Derek Muller, Emily Zhang and Petr Lebedev


  1. Sagar Agrawal

    Sagar Agrawal

    Acum oră

    Do they heat up or cool down while absobring UV light & whle emiting Fluorescence. body heat regulation

  2. Stem


    Acum oră

    как дела?

  3. Mangal Akkalkot

    Mangal Akkalkot

    Acum 3 ore

    Why is everything apart from text books so damn interesting and easy to grasp. 1. So basically now I feel humans actually aren't that forward, yeah I know ROfilm and the g board which I am typing on is by humans, but here UV light mutates our DNA to cause all sorts of disorder, and here are other organisms, which basically have an adaptation for that. 2 . ME initially : why didn't they just use a bottle of Vinegar to capture that scorpion, I am so smart........and then me the next moment to myself, " oh wait, what if that glowing thing is a metabolic activity and basically dead things lack metabolism, so no use, I am so dumb "

  4. Nigza Minja

    Nigza Minja

    Acum 3 ore

    Here's another hypothesis: Evolution isn't real An explosion can't create what we perceive as reality. In other words a tornado can't go through a junk yard and create a Boeing 747 if u knw what I mean. Evolution also violates many laws of physics such as bio-genesis and others. If the good doctor could look into that then I'd pay to see that video!

  5. Juan Rascon

    Juan Rascon

    Acum 4 ore

    My hypothesis: could it be that that it was a preferred mating trait? Much like peacocks or many other animals, exotic colors attract a partner, or maybe it also helps so that scorpions are able to find a mate in the dark, maybe even identify the gender by some difference in their glow. More often that not, counterproductive traits are kept by a mating preference in species.

  6. Vineet Verma

    Vineet Verma

    Acum 4 ore

    Scorpian is also a zodiac symbol. I think it shows some sort of energy, so may be Scorpians are more energetic at night.



    Acum 5 ore

    Gongrats for 1 crore subs👍😉😉😘💯💯😘😘



    Acum 5 ore

    Gongrats for 1 crore

  9. Rohit Chaudhary

    Rohit Chaudhary

    Acum 11 ore

    They want to be seen so other know it is dangerous

  10. Still Antelope

    Still Antelope

    Acum 11 ore

    uv can blind with flowers like spiders they can use it to sit on desert flowers (plants and rocks) or look like them and capture insects.

  11. The Lost Ronin

    The Lost Ronin

    Acum 11 ore

    Was shocked to find fluorescing scorpions in central NC - they were so small, about the size of a pencil tip, but clearly had green-glowing tails even under natural light. I haven't seen them since I got chickens 😂

  12. gziKmdDFrg


    Acum 12 ore

    Waiting for that veritasium video explaining why gravity doesn't exist

  13. Dani Paul

    Dani Paul

    Acum 12 ore

    Could you please make a video on how people age differently when they go through the black hole or something?

  14. El rey CHARMELEON


    Acum 15 ore

    Hey, who translates your videos in Veritasium en Español

  15. Feynstein 100

    Feynstein 100

    Acum 18 ore

    Should I stay or should I go? Scorpions are demagorgons confirmed

  16. Sinha S

    Sinha S

    Acum 20 ore

    Derek Can you make a video on working and physics behind cassette player

  17. Sachin


    Acum 22 ore

    Just my hypothesis maybe You already have it sir --> What if they are using UV light as their Biological clock I mean like in humans we differntiate between Day and Night on the basis of Sunlight mainly . And scorpions are nocturnal so at night it is good for them to hunt in moonlight or no light and when it is day time they hide in crack or under the stones to sleep or rest and during sunlight they can sense the UV lights comming from the Sun and their vision range is like in UV + Visible . UV during the time of when they originally arise and now they have even evolved to both ?? . Just my views if you are reading this Derek please reply , to correct my assumptions I am really fasinated about Scorpions . P.S Love Your Content Brother :)

  18. ImperialGoldfish


    Acum 23 ore


  19. Ross Giblin

    Ross Giblin

    Acum 23 ore

    Out of interest, did you use a full spectrum modified camera to shoot the night scenes? I understand it’s in the visual spectrum but it looks different, maybe that’s just the black light and the fact the black light is somewhat broad band

  20. the player

    the player

    Acum o Zi

    next video show us how does a molten salt reactor work's, im just curious cause in minecraft i can't figure it out in the NuclearCraft mod...

  21. Mehaz


    Acum o Zi


  22. TheNineOf144


    Acum o Zi

    Veritasium would you be willing to do a video on Sonoluminescence?

  23. The Pocket Chemist

    The Pocket Chemist

    Acum o Zi

    I can't believe that I just found this channel. It is just amazing. Thank you for this excellent content!

  24. Irfan Kazi

    Irfan Kazi

    Acum o Zi

    Following you on your ROfilm made me realized, we just not wasted money in our school but also TIME. ;(

  25. Yindog1


    Acum o Zi

    but the UV photobleaching process could be messing with the scorpion’s full body light detection independently of the fluorescence. It could be that the UV exposure over time destroys the light detection and also the fluorescent protein. So it does not prove that the fluorescence is related to light sensing.

  26. The Kingdom

    The Kingdom

    Acum o Zi

    The last hypothesis is most likely the correct one. Using their fluorescence to determine if it's night or day in-order to come out to forage for food. That makes the most sense out of all his hypothesis'.

  27. Richard L

    Richard L

    Acum o Zi

    What UV wavelength is best?

  28. Johnny Mike

    Johnny Mike

    Acum o Zi

    Do any words have relevance in space?

  29. Johnny Mike

    Johnny Mike

    Acum o Zi

    I’m watching your expanding episode … you used the words UP middle and front in like the same paragraph… do these words have relevance in space? 🐚

  30. that1yoshi •_•

    that1yoshi •_•

    Acum o Zi

    What would happen if you did another pool full of shade balls but use double the amount you used last year?

  31. Richard Baxter

    Richard Baxter

    Acum o Zi

    Heey! Was watching old videos of you in Spanish and found a video where you talked about what happens if you shake a bottle of soda. Now I have a question I couldn’t solve by my self: to preserve the soda, is it better to squeeze the bottle and close it? Keeping less air in the Bottle or is it better to just close it ? Would it make a difference?

  32. Pete da Bomb

    Pete da Bomb

    Acum o Zi

    Congratulations on 10.000.000 ! Love your videos!

  33. Md Ashiqur Rahman

    Md Ashiqur Rahman

    Acum o Zi

    Everybody gangsta until those things get inside your home and blend in the floor carpet :|

  34. Роман Пономаренко

    Роман Пономаренко

    Acum o Zi

    There is one thing that sometimes makes me embarrassed to watch your videos, when a person is talking to you, and you are staring at him with a giant camera, or when you are chatting over a video call and insert a video from your camera where you just like: (listens carefully and makes a smart look) - uhum.

  35. Len Taclof

    Len Taclof

    Acum 2 Zile

    His name should be Carl Kook.

  36. Me Eye

    Me Eye

    Acum 2 Zile

    They pretend to know they not in Plato's allogory cave sorry sure as hell they why you are deceive self guessing know became two wake the hell up is the k known age coming guess know void In know

  37. hawaiinnative


    Acum 2 Zile

    it was photon "collector"

  38. Jordan Daly

    Jordan Daly

    Acum 2 Zile

    “Should I go out tonight or should I stay in my hole?” -me every Friday night

  39. Chris Sturm

    Chris Sturm

    Acum 2 Zile

    I have a question I have been wondering about for some time now, and I hope you can answer it. In a video you did about 8 years ago called "Why the sky isn't blue " you talked about how the distance between objects is increasing so rapidly that eventually even light wouldn't be able to overcome the distance. My question is if space is expanding, and all objects are moving away from one another, how do things collide?

  40. D Man

    D Man

    Acum 2 Zile

    No uv light on my "smart" phone

  41. Lekolär-tuben


    Acum 2 Zile

    Hi, My family always watches your videos. We live in Sweden and this summer we went to Greece for vacation. We had a pretty large circular swimming-pool about 1 meter deep and about 10 meters in diameter. And me and my family started walking around the pool trying to get the pool in a circular motion. We asked some other people for help and they did help us. We were in total 7 adults and 5 kids doing it. The motion in the ocean :) began and every new person that entered the pool felt it and had to go with the flow direction. The funny thing is that we did this every day for a week and everybody believed that this was a pool that had fans and they swam around and around enjoying the pool. When we told people that this was not a mechanical motion and that it was started by us walking around most people did not believe us. The problem was that we just had an idéa that we tried and it worked but we could not explain it. You could make a video explaining this and I bet people with circular swimming-pools would go nuts over it. Sorry for my terrible english.

    • CrazyGaming


      Acum o Zi

      So what happens if someone decide to go in the opposite direction, would the circular motion believers shun them as deviants?

  42. Алек Зотов

    Алек Зотов

    Acum 2 Zile

    Hi. I have some strange questions for you. Perhaps you will try to answer in your next videos? If we assume that time has more than two directions (forward and backward), then what directions could they be? Can time have mass (naive question)? Can space exist without time? Can mass exist without time?

  43. KPbICMAH


    Acum 2 Zile

    5:40 "camoflauge", seriously?

  44. moonlite x

    moonlite x

    Acum 2 Zile

    pls do venturi effect

  45. Chandra Shekhar Balachandran

    Chandra Shekhar Balachandran

    Acum 2 Zile

    *Always* fascinating, and humorous to *just* the right extent! This is one of my favorite channels! Good work, team! And, thanks!!

  46. Antonis Papas

    Antonis Papas

    Acum 2 Zile

    Please do time crystals

  47. Mohammed Ahsan

    Mohammed Ahsan

    Acum 2 Zile

    Honey Vs Capital One

  48. Aaron Kelly

    Aaron Kelly

    Acum 2 Zile

    You could have provided chapter marks to make it easier for those of us who like to pay more when we shop.

  49. GRAndreas7


    Acum 2 Zile

    They moon in glowlight.... Well maybe I am the only one that read it like this :P

  50. MGE Gibs

    MGE Gibs

    Acum 3 Zile

    Wow this was actually so interesting I loved this

  51. Sentient Ape

    Sentient Ape

    Acum 3 Zile

    I just realized theres two camera men. One filming him filming

  52. Kim


    Acum 3 Zile

    Finally, now you changed your thumbnail - So now I can click it xD

  53. Darth Sidious

    Darth Sidious

    Acum 3 Zile

    What?! Im actually more impressed about the owl glowing thing. Didnt know that.

  54. Harrison Swadley

    Harrison Swadley

    Acum 3 Zile

    But do chairs exist?

  55. Mr Turtle11

    Mr Turtle11

    Acum 3 Zile

    Professor of Biology? Really? He is just making up stuff and "hypothesis"...

  56. Ron Haywood

    Ron Haywood

    Acum 3 Zile

    Rats also glow green in UV light. Great for locating those creatures at night for a bit of eradication!

  57. Somedude Ok

    Somedude Ok

    Acum 3 Zile

    Do spiders glow too? Since they are related to scorpions and scorpion got their fluorescence early on?

  58. Long legged Larry

    Long legged Larry

    Acum 3 Zile

    Surely the scorpion would move into the shadow while blind is just being too hot?

  59. Peter Pan

    Peter Pan

    Acum 3 Zile

    This could be aposematism against a certain type of predator or competitor that can see it while still be camouflaged for everyone else.

  60. Madhuraj


    Acum 3 Zile

    Veritasium fans, is there a Ve video about quantum entropy?



    Acum 3 Zile

    Hello sir! Could you sponsor a student for an online allowance. Its a big help. Thanks.



    Acum 4 Zile

    What if animal see each other at night this way... glowing under the moonlight... Similar to the Avatar movie

  63. Masked Vale

    Masked Vale

    Acum 4 Zile

    Those are some Rad Scorpions!

  64. Danish


    Acum 4 Zile

    Subscriber race between verstasium and September 15, 2021 Smarter Everyday for 10M And here's the winner Verstasium "The element of truth " with 10.1 M And Smarter Everyday still at 9.99

  65. Mystic Point Water Sports

    Mystic Point Water Sports

    Acum 4 Zile

    they reflect / attract elysium light

  66. Damir Subasic

    Damir Subasic

    Acum 4 Zile

    I just can't believe that someone has been getting paid for 10 years to figure out why scorpions glow

  67. Freakin Creeks

    Freakin Creeks

    Acum 4 Zile

    They sense the heat come on

  68. Hexl Art

    Hexl Art

    Acum 4 Zile

    I'm arachnophobic. I did not watch this video and will not watch it but the damn thumbnail made me throw my phone. Please change it.

  69. luiz alves

    luiz alves

    Acum 4 Zile

    I love that one of the current hypothesis for this man is "they glow so they can tell if they're glowing"

  70. Dustyclavier


    Acum 4 Zile

    What about not trapping them to experiment on them, torture them, kill them? Those guys must really like scorpios. Wtf is wrong with you people

  71. Wheat Tins

    Wheat Tins

    Acum 4 Zile

    Omg I live in Bakersfield… Heyy!!

  72. Pooh Jinping

    Pooh Jinping

    Acum 4 Zile

    Yes Derek I looooove overpaying when I shop

  73. Mohammed Belfaqih

    Mohammed Belfaqih

    Acum 4 Zile

    or you can use honey instead of capital one

  74. Goi Dogoi

    Goi Dogoi

    Acum 4 Zile

    I would thought the professor going to catch the scorpions by the tail to get them into the bottles. 🤔😁

  75. Tapaswi Satyapanthi

    Tapaswi Satyapanthi

    Acum 4 Zile

    I have a question trembling in my mind How to measure the distance between earth & a deep space object ? when it is said that some object is x billion or million light years far just based on light which we received from that object. Can you please….. make a video on this topic ?

  76. Matias Giraudi

    Matias Giraudi

    Acum 4 Zile


  77. aditya rathod

    aditya rathod

    Acum 4 Zile

    10million complete Congratulations 🎊

  78. William John

    William John

    Acum 4 Zile

    Investing in crypto now is very cool especially with the current rise in the market now

    • Jane Doe

      Jane Doe

      Acum 4 Zile

      @Shan Nara Hey you're not far from making profit, she has taking care of my account for months now...I have 16 win and 2 looses so far

    • Shan Nara

      Shan Nara

      Acum 4 Zile

      I just got recommended to her on ROfilm and I invested, please how good is she

    • Orla Brady

      Orla Brady

      Acum 4 Zile

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    • Orla Brady

      Orla Brady

      Acum 4 Zile

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    • Win Chester

      Win Chester

      Acum 4 Zile

      Really you known her?, I even thought I'm the only one she has helped walk through the fear and falls of forex Trading

  79. Amrit Sidhu

    Amrit Sidhu

    Acum 4 Zile

    Hello sir....please make a video on time crystals...!!

  80. Misaka -Railgun- Mikoto the ace of Tokiwadai

    Misaka -Railgun- Mikoto the ace of Tokiwadai

    Acum 5 Zile

    glow in the dark like the afro-american CIA gentlemen

  81. SteakLP


    Acum 5 Zile

    more interestingly, I wanna know why OWLs f*n glow!?

  82. mynuttyme


    Acum 5 Zile

    Not sure what part of them is fluorescent but even a smashed scorpion on a sidewalk reflects light like this. So it's not their skin.

  83. mynuttyme


    Acum 5 Zile

    No, they are fluorescent for us to find them easily in the dark. Especially then you found one lying on your pillow 🙃

  84. Things Explained

    Things Explained

    Acum 5 Zile

    Congratulations on 10 million subscribers sir👏👏👏

  85. Bhupathi turaga

    Bhupathi turaga

    Acum 5 Zile

    Why the Speed of light is constant

  86. Firenzar Frenzy

    Firenzar Frenzy

    Acum 5 Zile

    I’m wandering how they eliminated heat as a variable in the lamp experiment. Could they just be seeking heat relief or do they know light=heat and so if they avoid heat in the shade they are therefore avoiding the light?

    • Auf der Suche

      Auf der Suche

      Acum o Zi

      The way they visualised the experiment, led me to the same thought. But I guess with some distance between the lights and the scorpions, and perhaps LED lighting, heat may not be an issue.

    • Scarlet


      Acum 2 Zile

      They would have to control for temperature.

    • Somedude Ok

      Somedude Ok

      Acum 3 Zile

      Aren't there lamps that don't get hot?

  87. David Fryer

    David Fryer

    Acum 5 Zile

    On our property in Arkansas, we had a place we called "Scorpion Hill". When I was 8 or 9 8 I began to preserve them. I enjoyed showing them at school. Everyone loved them. Some were afraid at first, but I think I may have contributed to scorpion awareness. Back in those day kids did not come to school without pocket knives. Today the schools would consider my dead scorpion a weapon and expell me permanently. Silly no tolerance policies! I was always fascinated with the odd color of their bodies. If only I had known they glowed in ultra violet light. I am surprised I did not figure it out my self. SOME DIAMOND FROM ARKANSAS GLOW ALSO. PLEASE EXPLAIN WHY. There is a man from Texas on ROfilm who demonstrates this fact!

  88. High Q

    High Q

    Acum 5 Zile

    IS IT POSSIBLE that its not the light they sense, but the heat or energy from the light rather.

  89. Nib-Na5ty


    Acum 5 Zile


  90. Emre Eren

    Emre Eren

    Acum 5 Zile

    out of curiosity.... do you hold a degree? i was amazed by your videos and my mom was hoping to use you as a reference for information source on your videos,.... maybe you could reply pm and i would appreciate it. Thank you.

  91. PiTheNumber


    Acum 5 Zile


  92. Gio Gwno

    Gio Gwno

    Acum 5 Zile

    The standing bulb genotypically pull because dash classically heat in a meek theater. ritzy, lonely freeze

  93. Devon Bauman

    Devon Bauman

    Acum 5 Zile

    I just found a scorpion in my room last night

  94. Austin


    Acum 5 Zile

    ok now do corals

  95. TheBoojah


    Acum 5 Zile

    Perhaps they are using their EYES to know if it's a full moon?

  96. Nonononono Ohno

    Nonononono Ohno

    Acum 5 Zile

    03:25 This proves that scorpions fluoresce in order to repel insects.

  97. Sync


    Acum 5 Zile

    Here at 10 million!

  98. Al


    Acum 5 Zile

    Prof Klook: Gently nudge them in the container... Veritasium: *WHACK!* There you go 😂😂😂

  99. Honrobo Kadoma

    Honrobo Kadoma

    Acum 5 Zile

    In Africa we poor. We use scorp as reward for good tribal childen.