Thanks to Skillshare for supporting this episode
of SciShow. [ ♪ Intro ] At some point in your life, you’ve probably
heard someone say, “you are what you eat.” Like, when your parent saw you wash down an
entire pizza with a 2-liter bottle of whatever your caffeinated beverage of choice is. Or you watched Violet Beauregarde turn into
a giant blueberry. Well, it turns out there are creatures out
there in the real world who do get some super important and recognizable part of their biology from their diets. From single-celled organisms to terrifying
dragonfish, here are seven life forms that take the phrase “you are what you eat” to heart...or stomach. A lot of birds get their coloration from their
diets, but perhaps the most striking is the blue-footed booby. Named for, well, you know… its blue feet. These seabirds are found in the Galapagos
and along the western coasts of Central and South America. And despite the name, their feet actually
range from dull blue to bright green. The color comes from a combination of the
structural protein fibers in their feet and carotenoids, pigment proteins similar to the
ones that make carrots orange and flamingos pink. Animals can’t make carotenoids themselves,
they have to get them from their diets. In the blue-footed booby’s case, they come
from fish like anchovy and sardines, which in turn get them from the stuff they eat. Studies have shown that a lack of fish not
only dulls a male’s feet, it also lowers his immune defenses. That means vibrant feet are what scientists
call an honest signal of a booby’s hunting success and health. That’s probably why the courting dance for
these birds is all about showing off those colorful toes. And it’s not just the males saying “Look
at my bright feet, ladies! I’m healthy and can feed you!” Females get judged by their feet, too. Males spend less time incubating the eggs
of dull-footed females, unless those eggs are large enough to show that the female put extra investment into their chick. Speaking of vibrant color, you’ve probably
heard of poison frogs, or as they’re sometimes called poison dart frogs, even though only a few species of the couple hundred in the family Dendrobatidae seem to have actually been used that way. The thing is, as far as we know, none of them
actually make the toxins they’re named for. A poison frog’s potency is due to the special
mix of alkaloids that it gets from munching on critters like beetles, ants and millipedes. Alkaloids are high-pH, or basic, compounds
that contain nitrogen atoms. And you’ve certainly heard of some, like
caffeine, nicotine, and morphine. One of the deadliest is batrachotoxin, which is found in really high concentrations in the skin glands of the most toxic poison frogs. It jams open channels in your cell membranes
that let sodium ions cross over, and that jamming causes muscle contractions, heart
palpitations, and even cardiac arrest. Thanks to a single mutation in their own sodium
ion channels, the frogs can resist these effects. It’s unknown how poison frogs resist other
alkaloids; some researchers suspect they may just break them down faster than we do. It’s also not really known how these toxins
move from stomach to skin glands, but whatever happens, it allows the frogs to store them
for years. And some mother frogs actually feed their
tadpoles with alkaloid-laden unfertilized eggs so they become poisonous long before
they can wrangle bugs. But unless you’re trekking through rainforests
in Central and South America, any poison frogs you’ve seen are probably harmless. Captive poison frogs usually aren’t fed
the same toxic diet as their wild counterparts, so they’re pretty, but no longer pretty
deadly. Assassin bugs are so named because they’re
prolific hunters. But some young assassin bugs take that reputation
to a whole ‘nother level. They don’t just kill, they wear the bodies
of their victims as a kind of corpse armor. Assassin bug nymphs hunt a variety of prey,
but ants have a special fate. They pierce the ants’ exoskeleton with their
sharp mouth parts, and inject a paralyzing saliva and digestive enzymes which dissolve the ant’s interior tissues into delicious, slurp-able smoothies. Then, instead of discarding the newly hollow
husks, the bugs fashion them into tasteful outerwear. They can carry the corpses of up to 20 ants
at once, and the cluster can be bigger than their entire body! Some researchers have suggested that they
make these adornments to provide a kind of smell-based camouflage so they can sneak up
on future meals. Others say it’s so predators don’t recognize
them as prey, and there’s some evidence to back that idea up. A 2007 study found that jumping spiders, which
have a poor sense of smell, but really good vision, attacked naked bugs roughly 9 times
more frequently than the ones sporting ant camo. Of course, that doesn’t mean the dead ants
don’t help hide the bug’s smell, too. Like the best items in your wardrobe, corpse
armor could have multiple uses. Halophilic heterotrophic protists are single-celled
organisms that eat bacteria and live in super salty ponds, like the ones we make for harvesting
sea salt. The salt in such waters can vary a lot, and
that’s not good for living things. So to survive, these protists have stolen
genes from their food. Saltiness is a problem because it makes it
tough to control the water content of cells. If there’s less salt on the outside of a
cell, a lot of water will get pushed into the cell, eventually popping it like a balloon. When the water outside a cell has more salt,
like in these super salty ponds, then the water inside the cell leaves in a futile attempt
to balance things out, turning the cell into a sort of pickled raisin. Luckily, a handful of protists have found
a way to survive their saline sanctuaries: special compounds like ectoines that help
them stay hydrated. Ectoines can accumulate in great numbers inside
a cell without disrupting the normal goings-on. So they’re really good at preventing cells
from getting damaged as water gets pushed into or out of them. At first, the protists probably just stole
these ecotines from the bacteria they ate. But then, at some point, they actually stole
the genes that the bacteria use to create the ectoines in the first place, and incorporated
them into their own DNA. It’s a phenomenon known as horizontal gene
transfer, and is really popular with bacteria, but is much rarer in protists and other species
that protect their genome in a membrane-bound nucleus. Deep in the darkness at 500 to 1000 meters
below sea level, the pitch-black stoplight loosejaw hunts. This dragonfish is able to see things others
that dwell in the deep can’t because it can pick up on deep red and near-infrared
light. But it doesn’t have that ability innately. It gets it from its meals. The gaping maws of dragonfish are well equipped
for snacking on other fish, and the stoplight loosejaw is no exception. But a lot of the time, their fare is much
smaller: zooplankton. When scientists have dissected these fish’s
stomachs to see what’s in them, large calanoid copepods can comprise up to about half of the contents by weight. These copepods are 1000 times more abundant
down at the loosejaw’s hunting depths than the fish or shrimp they might otherwise eat, so it makes sense that they snack on them while searching for bigger meals. But they don’t just eat them for the extra
calories. They supply stoplight loosejaws with the pigment
that allows them to perceive deep red and near-infrared light. Most fish at deeper depths are only really
sensitive to short, blue and green wavelengths of light because longer wavelengths just don’t
make it that far down. But the loosejaw doesn’t rely on rays from
the sun, it can produce deep red light in special light-producing organs beneath its eyes. And it even wouldn’t be able to see that
light if it weren’t for the usual pigment it probably gets from copepods. There are some details that still need to
be ironed out, but because the pigment is similar to one found in a species of bacteria, scientists think the copepods get the pigment from bacteria they eat, and then pass it along
when they get eaten by the dragonfish. The eastern emerald elysia sea slug stands
out as one of relatively few animals that can live off of light like a plant. But, spoiler! that’s a unique trait they
get from their food. Juveniles off the eastern coast of North America
eat a bunch of different species of algae. But starting as young adults, they focus on
one. And as they munch away, they actually take
the algae’s chloroplasts, the organelles in their cells responsible for photosynthesis, and store them in pouches in their digestive tract. Remarkably, they can actually use those chloroplasts
to run on solar power. In fact, experiments have shown they can go
without eating for over nine months! We don’t currently know they keep these
sun-harnessing tools running, though. Chloroplasts need proteins made by other parts
of a cell to function, parts that animals don’t generally have. Some scientists think the slug stole algal
genes a long time ago, kind of like the protists we talked about earlier, but other studies have suggested that’s not the case, and it just uses the relevant bits of DNA without
putting them into its genome. Somehow. We also don’t really know why the slug’s
stomach or immune system doesn’t just destroy the foreign cell parts. Though studies have found that the animals
express different genes when exposed to the algae, including ones that change how their
bodies respond to foreign cells. And we don’t even know if they really need
to be solar powered. Research from 2014 found that these slugs
can actually survive in the dark and when injected with chemicals that inhibit photosynthesis. A lot of these questions could be answered
with further studies, but unfortunately, their populations are dwindling and it’s tough to raise them in captivity, so very little research is being conducted on them now. The blue dragon nudibranch is known for its
vibrant color. It spends its days floating on the ocean surface
hoping to run into something tasty to eat, like Portuguese Man o’ War. You’d think these squishy little slugs would
be easy pickings for other ocean predators, but they’re not as defenseless as they seem,
thanks to their toxic diet. Like other Aeolid nudibranchs, as larvae,
they have shells, but they lose them as they grow into adults. Without that shell for protection, they have to find another way to keep predators from gobbling them up. And they do that by stealing special toxin-delivering
cells called cnidocytes, from their food. Inside each cnidocyte is a stinging tool called
a nematocyst. It has a small trigger hair that sticks outside
the cell. When something brushes it, like a large fish
looking for a meal, water rushes into the cell. The pressure change causes a toxic harpoon
to shoot into the offender. Luckily for blue dragons and their cousins, they’ve developed adaptations to defend themselves against their preys’ stings. Depending on the species of nudibranch, some
have mucus, and some have hard chitin plates inside their mouth, throat, and digestive tract that the stingers can’t penetrate. Some of the stinging cells that don’t get
triggered are pushed through the walls of the nudibranch’s gut into appendages called cerata. There, they’re stored in special sacs until
they’re used. And just like the poison frogs, these nudibranchs
are vibrantly colored, a signal for predators to stay away. Taking on the properties of your food is really
just another cool way nature has managed to adapt to a situation. Need help hunting? Boom! See light none of your neighbors can. Need help not being hunted? Bam! Stab them with toxic needles. So you might be feeling a little jealous you
don’t get any cool physical properties from chowing down on last night’s leftovers. But maybe that’s a good thing. At least it is for me, because my diet is
like 90% junk food. Now, in my defense, cooking can take a really long
time. Which is why I’m glad that Skillshare has
me covered. Skillshare has a class called Quick and Healthy
Dinner for (Really) Busy People, taught by food bloggers Ceri Marsh and Laura Keogh. It teaches you how to make easy and fast dinners
that are also good for you, even if they don’t give you cool traits like the species in this episode. The class feels like a good reminder that
there are always new things to learn, even when it comes to something as simple as cooking. And since Skillshare has more than 20,000
classes about everything from sewing to animation, there’s also a lot more to explore. Right now, Skillshare is offering SciShow
viewers 2 months of unlimited access to all of their classes for free. You can follow the link in the description
to check it out! [ ♪ Outro ]
