There Are Crystal Mirrors Hidden in Scallop Eyes

There Are Crystal Mirrors Hidden in Scallop Eyes


[INTRO ♪] We usually think of scallops as tasty, pan-seared
delicacies, or the classic shape of clipart seashells. But last week, biologists revealed that they’re
worthy of way more than a special spot on a menu: Their visual system is amazingly complex, and includes up to 200 telescope-like eyes. Most eyes, from the fancy compound eyes of
bees to our own simple ones, focus light with a lens onto a retina, which contains light-sensitive photoreceptors. Scallop eyes, on the other hand, use mirrors
to do this focusing, which is why people sometimes compare them
to telescopes, like Hubble, despite their tiny size. This much had been known for half a century, thanks to a British vision researcher. But what the mirrors are made out of, and exactly how sight worked for the scallops,
remained a mystery. That’s mostly because their eyes are only
about a millimeter big. And every time scientists tried to prepare
the delicate eye tissue for a microscope, samples dried out and fell
apart. Enter cryogenic scanning electron microscopy,
or cryo-SEM. The technique uses liquid nitrogen to quickly
chill samples, allowing researchers to keep tissue intact
and hydrated. Reporting in the journal Science, a team used this method and discovered that
scallop eye mirrors are made out of guanine. You might have heard of guanine because it’s
one of the four bases that makes up DNA. But crystals made of guanine have weird optical
properties that many organisms use to survive. Like, it’s what makes fish scales look iridescent
or shiny. In scallops, the guanine crystals are in the
shape of square tiles. These tiles are stacked 20 to 30 sheets thick, each layer separated by a bit of cytoplasm. And they’re arranged to form a curved mirror
at the back of each eye. This is similar to how segmented mirror telescopes— the largest and most powerful telescopes in
the world—focus light. So, scallop eyes are more like the James Webb
Space Telescope than Hubble. The researchers think the precise layering
of the crystals causes them to mostly reflect blue and green
wavelengths of light— which is what you’d expect a scallop to
need to live under the sea. And maybe even more impressive is the fact
that scallop eyes have two retinas. Instead of being at the back of the eye, like
ours, the retinas are two strips of tissue in the
middle of the eye, onto which light gets focused after it’s
reflected off the back mirror. The team took a 3D scan of the eye, and simulated some views with a computer. From these models, they saw that the guanine
mirror is uniquely shaped and oriented to focus different
light on each retina. So they think scallops see two images at once. The smaller, outer retina appears to be specialized
for quick changes in light that are directly in front of the eye, like the sudden shadowy presence of a predator. And the larger inner retina is better at picking
up light in the periphery. It’s also more sensitive to light overall,
and gives the clearest picture. So biologists think this retina is important
for the scallop to keep tabs on its surroundings, even in
low-light. Which is probably pretty helpful if you live
under a rock in the ocean. And now: More sea creature news! Because last week, a team of biologists also
announced that they think the first animals to break off
from all others and form a separate branch on the tree of
life were sponges, not comb jellies. It’s a debate you probably didn’t know
was happening. But it has huge ramifications in thinking
about animal evolution. And for years, scientists have been split
on the matter. Sponges, also known as poriferans, are very
simple animals. So simple that many people confuse them with
plants. They don’t move or have any organs to speak
of. Instead, their bodies are full of pores that
let water pass through. And specialized cells called choanocytes capture
food particles in the water. Comb jellies, or ctenophores, are also pretty simple, although not as much as sponges because they actually have a basic nervous system. And they look kind of like jellyfish, but they don’t have any stinging cells. The confusion has been over which of these
animals is the sister to all others, or what scientists call the sister group. In other words, if you look at the evolutionary
tree, which group is split off by itself from other
animals. This doesn’t necessarily mean one animal
is older than another, or that we humans evolved from one or the
other. What it does tell us, though, is what the
common ancestor of all animals might have been like. The problem is that researchers have gotten
different answers when they look at the genomes of these animals, compare them to others, and use computer models
of evolution to make a phylogenetic tree. If you include specific amino acid changes,
you usually get sponges. But if you exclude those, or include distant
organisms, like fungi, you usually get jellies. In the latest study, researchers used more
statistics to filter out noise in all the data, and concluded
that sponges were the real deal. Some scientists may still nit-pick at this
result, but others seem convinced that the debate
is almost over. And it kind of makes intuitive sense that
the simpler animal is at the root of the family tree. The opposite finding would have meant that sponges would have had to lose their more
complicated organ systems from a shared common ancestor. So, there you have it. An updated family tree for all of us… at least until we get more data to complete
the puzzle. Alright, time for an announcement! You may have heard of this by now, but we here at SciShow are trying a new thing. Sometimes—all the time—it’s hard to figure
out what presents to get for people. But we come across weird, cool science-y things
all the time that we love and we think you or someone you
know might love. So we’ve created a store called SciShow Finds. It’s got a limited list of items that we have
in very limited quantity. Stuff that lets you learn, or experiment on
yourself, or just show how enthused you are about the
wonders of the universe. Someone you know is guaranteed to love these
socks or this lapel pin! And we’ll add new items as we find them to replace these ones as they sell out. A lot of them already sold out. And, when you buy from SciShow Finds, you’re also helping support SciShow, which
I appreciate a lot. So, thanks for doing that! [OUTRO ♪]

100 Comments

  • Alex Bambury

    December 9, 2017

    Anyone else notice the Father Ted reference

    Reply
  • J.R. Zippie

    December 9, 2017

    did I really need to know this???

    Reply
  • Jpxella

    December 9, 2017

    Do memes kill brain cells?

    Reply
  • ThatDarnSkag

    December 9, 2017

    That British researcher must’ve been quite the visionary.

    Reply
  • Corfal

    December 9, 2017

    2:41 Is Stefan doing an impression of Hank?

    Reply
  • Mr. V

    December 9, 2017

    THOSE SCALLOPS ARE RAWWW!!!

    Reply
  • TheFreePantheist

    December 9, 2017

    Why do scallops need to see?? What could they possibly do with that information

    Reply
  • Matt Boyd

    December 9, 2017

    Next video should be on how there's only two genders.

    Reply
  • Emily Kelbell

    December 9, 2017

    Omg! I thought he was naked! With bjust one nipple. That shirts got to go. Sorry. Too close to skin color.

    Reply
  • Mad Panda

    December 9, 2017

    so spongebob is our distant cousin?

    Reply
  • a998

    December 9, 2017

    Sponges are simps.

    Reply
  • Tea &Cats

    December 9, 2017

    Ew?

    Reply
  • Brendan Hart-Nutter

    December 9, 2017

    The host's shirt, skin, and background are all very similar colors today. I'm not a fan of the visual composition. That said great content as always.

    Reply
  • CybershamanX

    December 9, 2017

    Cue someone developing a VR program to simulate what it's like to see as a scallop. In other news, as far as the sponge revelation goes, does that mean I need to find an updated version of that giant "Tree of Life" chart that I like to look at from time to time? Here's an example of what I'm talking about: https://mcdb.colorado.edu/images/tree_o_life/ 🙂

    Reply
  • GirtheAlienGoldfish

    December 9, 2017

    #TeamJelly

    Reply
  • 3800Tech

    December 9, 2017

    All the hole and pores in sponges make them……….HYDRODYNAMICALLY DESIGNED!!!

    Reply
  • ALAPINO

    December 9, 2017

    Adpocalypse = No Iron?

    Reply
  • goodstrong

    December 9, 2017

    He needs to iron the button strip on his shirt.

    Reply
  • Tom Morgan

    December 9, 2017

    "You may have heard of this by now" is the understatement of the year.

    Reply
  • Justin Mielke

    December 9, 2017

    So in a way scallops invented telescopes before humans

    Reply
  • brujaja Aknot Wrought

    December 9, 2017

    Didja notice the presenter's shirt exactly matches his ears? Looks cool. Also, really really interesting content. Trilobite eyes are pretty amazing too. Surprising that in all these years of eating scallops we never noticed theirs.

    Reply
  • calitotos

    December 9, 2017

    WE ARE COMPLEX SPONGES

    Reply
  • DysnomiaFilms

    December 9, 2017

    So scallops have really ugly donut bokeh?

    Reply
  • Hendra Johan

    December 9, 2017

    When you become two , it is very creepy….

    Reply
  • Mike Meyer

    December 9, 2017

    IIRC, human eyes have two different types of receptors in two different areas, but our brain integrates those different types of signals into a single image. Scallops seem to have pushed that idea even further, but what about that further would cause them to not be able to integrate the signals into one image?

    Reply
  • markd315

    December 9, 2017

    Help for vegetarians:

    Shallots ✅
    Scallions ✅
    Scalloped potatoes ✅
    Scallops🚫❗️ (animal. Technically.)

    Reply
  • AtarahDerek

    December 9, 2017

    How, pray tell, does arguing whether great-great-great grandpa was a jellyfish or a sponge advance science, medicine or technology?

    Reply
  • Dan Calbrook

    December 9, 2017

    2:41 – taken over by the spirit of hank for a second haha

    Reply
  • Joey Ouyang

    December 9, 2017

    Just evolution amirite

    Reply
  • Anonymous 616

    December 9, 2017

    Know ur food

    Reply
  • shingshongshamalama

    December 9, 2017

    These telescopes are small. THOSE telescopes are far away.

    Reply
  • rilluma

    December 9, 2017

    who is the british vision scientist you mentioned 0:39
    ???

    Reply
  • Harika Mohan

    December 9, 2017

    Aww… what a nice way to celebrate Christmas – filling in our family tree.

    Reply
  • Joe American

    December 9, 2017

    I really enjoy this channel. Thank You for the work and research y'all put in.

    Reply
  • Robert Szasz

    December 9, 2017

    Small, Far Away….. Small , Far Away

    Reply
  • Olan Kenny

    December 9, 2017

    "Small"
    "Far away"
    Was that a Father Ted reference??

    Reply
  • Ben Schofield

    December 9, 2017

    Can you pronounce scallop right at least?

    Reply
  • Merry Machiavelli

    December 9, 2017

    Do scientists think that scallop eyes evolved independently? They are so different, I would assume so. I wonder if we do ever encounter alien life, whether scallop-like eyes might be just as likely as vertebrate-like ones (assuming aliens have eyes at all).

    Reply
  • Mr. Dr. Genius

    December 9, 2017

    An announcement? I wonder what it could be.

    Reply
  • Crawl IntoTheCalm

    December 9, 2017

    The tree of life is planted in feces because….

    GOD!

    Reply
  • Pivot Boom

    December 9, 2017

    Why does everyone talk in a similar style? lol

    Reply
  • Goon Smith

    December 9, 2017

    Sorry, you forget Placozoa, on Genomic structure level, they are way more basal compared to Ctneophora or sponges. So most ancient animal is Trichoplax adhaerens, not Spongebob

    Reply
  • Mohammad Aluthainah

    December 9, 2017

    & yet scallops don't have brains 😂 that's a mystery of life 😅

    Reply
  • silvereaper1

    December 9, 2017

    2:41 "and now more sea creature news"

    Reply
  • US

    December 9, 2017

    Anyone else get slightly annoyed that Scallops and Scallions sound so similar?

    Reply
  • A

    December 9, 2017

    EYES ON THE INSIDE

    Reply
  • Manic8Ball

    December 9, 2017

    "Sponges are the real deal" means what? They are the sister of other animals, or they're the ancestor of (mostly) all animals? That wasn't at all clear.

    Reply
  • Alex Mercer

    December 9, 2017

    When I see scallops, I think Spongebob.

    Reply
  • MrStensnask

    December 9, 2017

    Ockham's Razor suggests it's the sponges that are the oldest group of animals

    Reply
  • jesse mckeown

    December 9, 2017

    @szyzyg, 0:36

    Reply
  • hannahclipse

    December 9, 2017

    4:59 stuff that's let's you experiment on yourself

    Hmm I'm interested 😉

    Reply
  • Johnus Smittinis

    December 9, 2017

    It really baffles me how these eyes developed through natural selection. Let's say millions of years ago or whatever, the scallops were developing eyes, but no mirrors within, and all died because they couldn't see.

    Reply
  • that_marc_guy

    December 9, 2017

    and to those who like sushi, if you ever see scallops on the menu, try it, you'll be glad you did.

    Reply
  • Jonathan Eckstein

    December 9, 2017

    You need to iron your shirt better…

    Reply
  • tawon1984

    December 9, 2017

    So SpongeBob has been jelly fishing since the dawn of time 👍

    Reply
  • Orenotter

    December 9, 2017

    Since evolution is the doctrine of a made-up religion, my money is on neither.

    Reply
  • Tristan Wintle

    December 9, 2017

    This is fascinating. It makes me wonder what the world would be like if human eyes evolved like those of scallops.

    Reply
  • Hannah M

    December 9, 2017

    Loving the Father Ted reference

    Reply
  • NighteeeY

    December 9, 2017

    Well i mean….if they had amazing eyes…..they wouldnt end up on our plates am i right?

    Reply
  • Christian Gingras

    December 9, 2017

    I had faith in sponges. I am happy that they won the title of most primitive animal.

    You rock sponges!

    Reply
  • Ana Raluca

    December 9, 2017

    Did anyone else notice the dash line is moving?

    Reply
  • MoreAmerican

    December 10, 2017

    Learn how to iron a f’ing shirt lol.

    Reply
  • Awang Budiman

    December 10, 2017

    Who would win?
    An abundant food source.
    vs
    One angry Scottish boi.

    Reply
  • BeginPanicAttack

    December 10, 2017

    1 : why do scallops need to see
    2 : everything humans pat themselves on the back for inventing has been around for millions of years

    Reply
  • PalaeoJoe

    December 10, 2017

    The sponge thing: "In other news, The picture of the tree of life you got from your Zoology textbook is still the same! " Thanks you??

    Reply
  • Vectored Thrust

    December 10, 2017

    0:36 Oh wow, that Father Ted reference xD

    Reply
  • Symix

    December 10, 2017

    Scishow comments in a nutshell: uh i dont like the host.

    Reply
  • Amar Maima

    December 10, 2017

    رؤ412ء6688565£65!•32`3111`1

    Reply
  • TheDroidBay

    December 10, 2017

    This is the internet. I am determined to find the blazing sponges vs comb jellies argument rapidly turning into war in the comments.

    Reply
  • SKPjoe Coursegold

    December 11, 2017

    scallops with a side of sponges, please.

    Reply
  • Adam Thompson

    December 11, 2017

    Why is shishowfinds not linked in the description?

    Reply
  • dannyoman

    December 11, 2017

    Sword give me sight beyond sight , thundercats ho !

    Reply
  • utkua

    December 11, 2017

    What are they doing with eyes ? Stand still when there is danger, and stand still when there isn't ?

    Reply
  • apcolleen

    December 12, 2017

    You are over drying your clothes.

    Reply
  • Mase D

    December 12, 2017

    Iron that shirt boy!

    Reply
  • Travis Nicolaisen

    December 12, 2017

    I hate this guy… rarely watch videos with him no matter how interesting the video seems…

    Reply
  • TheHolyHandGrenade79

    December 13, 2017

    Well, I guess that scallops can't see vampires.

    Reply
  • Carlos

    December 14, 2017

    Scallop eyes creep me out so much

    Reply
  • Figgy

    December 15, 2017

    One millimeter 'BIG'?~!

    Wide?
    In diameter?

    This triggered me something terrible.

    Reply
  • culwin

    December 17, 2017

    I wonder how TierZoo rates scallops

    Reply
  • Michal Šeps

    December 19, 2017

    The "sister group"? ( ͡° ͜ʖ ͡°)

    Reply
  • Mikes Science

    December 19, 2017

    I never thought I would learn so much about sponges so quickly

    Reply
  • Craig Gordon

    December 23, 2017

    Small. Far away. Was that a Father Ted reference?

    Reply
  • Todd Starbuck

    December 28, 2017

    "Enthuse" is not a thing. Stop trying to make it a thing.

    Reply
  • Chad Castagana

    December 28, 2017

    0:24 Vertabrate eyes are not simple, they are monocular – big difference

    Reply
  • TheJordanChronicles

    December 29, 2017

    Keep this guy away from playgrounds and kiddie pools

    Reply
  • Fredrik

    December 30, 2017

    I get a bit annoyed when people refer to "intuitive sense"/common sense in a scientific context.

    It's notorious for being misleading and often flat-out wrong (and often differ wildly between different people). You can't just use intuition to support your arguments when once in while they seem to match, and ignore all the times they don't. This is precisely why we have scientific studies, to get away from that stuff.

    Reply
  • Canaan

    January 4, 2018

    I wish you showed more pictures of them I'm not really sure what they look like other than when they're on a plate then they are little white discs of deliciousness

    Reply
  • Daniel McDavid

    January 5, 2018

    A new study published in the best scallop journal finds that humans have two types of cells in their retinas. We believe that they see two separate images: one that is precise and colorful but needs bright light, and one that is grayscale, but needs relatively small levels of light.

    Reply
  • The YouTube Phantom Official

    January 6, 2018

    some of the most beautiful eyes in the animal kingdom imo

    Reply
  • ChemicalChrisOttawa

    January 6, 2018

    CryoSEM, we always use liquid ethylyne, not nitrogen…

    Reply
  • Laurence Killen

    February 10, 2018

    Pretty sure that there was a Father Ted easter egg in this. Small…Far away.

    Reply
  • Federico Jimbo Smithson

    April 8, 2018

    I wish there's an app or simulation where we can experience other animals' point of view

    Reply
  • Jordan Rael

    June 13, 2018

    why did you guys hire this guy he doesn't know how to do this s***

    Reply
  • Matthew Harris-Levesque

    July 19, 2018

    4:58 – Or experiment on yourself…

    … wait.. where's the disclaimer?

    Reply
  • Jordan Rael

    January 15, 2019

    I wish i could block all of the videos hosted by this guy! Only his tho cuz i absolutely love the other hosts

    Reply
  • Yamaly Barragán

    March 24, 2019

    Does anyone know the latest article which says sponges are the sister group of animals?
    Share it, please?

    Reply
  • Puppy Pi

    March 26, 2019

    But do they use adaptive scalloptics? 8}

    Reply
  • mike archer

    August 8, 2019

    It's pronounced SKOLLOPS .

    Reply
  • mike archer

    August 8, 2019

    Father Ted lovefest going on…

    Reply

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