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of SciShow! [♪ INTRO ] Everyone knows that the reptiles in the order
Testudines, the lineage collectively known as turtles, are totally tubular. Those that don’t put on colorful masks and
fight crime play important roles in the ecosystems they call home. But although they all share a recognizable
body plan, individual turtle species have evolved traits that allow them to do remarkable
things like survive icy water or pee out of their mouths. I guess when you’ve had a couple hundred
million years on this planet, you’ve had the time to evolve all sorts of amazing abilities. Those traits, in turn, are teaching biologists
how life adapts to environmental challenges and giving them greater insights into how
animal bodies work. And we think that’s pretty rad. So here are 6 of our favorite bizarre turtles
from around the world. Let’s start our list with this lovely log! I mean, uh, it’s actually the mata mata
turtle. The mata mata is a large freshwater turtle
that can be found in the Amazon and Orinoco basins of South America … if you know what
to look for. Despite growing to be as much as a meter long
from nose to tail and weighing over 17 kilos, mata matas can be pretty hard to spot thanks
to their exquisite camouflage. Their shells or carapaces are often compared
to tree bark and their necks to soggy leaves — so, an unassuming fish will swim by near
what looks like a mess of plant material and boom, the mata mata has its lunch. But pulling off this disguise means the turtles
have had to make significant changes in a few ways, particularly from the neck up. Part of pretending to be a rotting log means
sitting still for long periods of time. And that’s where the turtle’s weirdly
long neck comes in. Its neck is longer than its spine, so it can
keep the rest of its body still while it sticks its nose out of the water like a snorkel. Biologists have taken a lot of interest in
those long necks as well as their flattened heads because they help the turtles slurp
down their meals. Thanks to some specialized muscles and bones,
mata matas can create a strong vacuum when they extend their necks while quickly opening
their wide mouths. And by studying the mechanics of how they
eat, scientists just might learn how to engineer underwater machines that really suck but in
a good way. When it comes to long necks, though, the mata
mata has nothing on its cousin the eastern long-necked turtle. It’s one of several species often called
snake-necked turtles because their necks are so long they make snake-like S shapes, especially
when they tuck them under their shells for protection. But… that’s not why they’re weird. In fact, what makes them weird might not seem
weird to us, but it’s really weird for a turtle: they determine sex with chromosomes,
kind of like we do. You can find these turtles throughout eastern
Australia in slow-moving bodies of water, like lakes and near dams. In fact, they’re found in so many different
aquatic habitats that they’re thought to play a big role in dispersing the algal species
that can grow on their shells. And part of their success as a species might
be because of those sex chromosomes. The vast majority of turtles have temperature-dependent
sex determination, where an embryo develops as male or female based on the temperature
it experiences during development. That temperature mostly depends on where and
how the female turtle digs her nest. And it’s a very useful way to determine
sex when there are other reasons incubating at a certain temperature helps each sex survive
better. But it only works if the environment doesn’t
change too much — if temperatures creep up, for example, you’re suddenly left with
an entire generation of just males or just females. Eastern long-necked turtles use genetic sex
determination instead — they have an XX/XY system that’s kind of like ours, except
that their chromosomes are much smaller. So small, in fact, that they’re called microchromosomes,
and they were only discovered recently because they couldn’t be detected using traditional
chromosome-visualizing methods. Understanding why these turtles use chromosomes
instead of temperature can teach biologists a lot about how different sex determination
methods evolve. And, because relying on chromosomes means
each generation has a roughly 50/50 split of sexes no matter what happens to the world
around them, it may explain the turtles’ ability to live and reproduce in such diverse
habitats. It could even mean they’re better equipped
than other turtles for future climatic changes — though, only time will really tell if
that’s the case. The leatherback sea turtle is as amazing as
it is massive. So, very. Leatherbacks — a name which comes from the
tough, rubbery skin on top of their shells — are the largest turtles alive today. The biggest one ever recorded was over 3 meters
long and weighed almost 1,000 kilograms. But, what’s really impressive about leatherbacks
is that they’re everywhere — and that’s probably because they’re the only reptiles
we know of that can stand below-freezing water temperatures. They have the widest range of any turtle,
and can be found in open oceans from the chilly waters of Alaska to the Southern tip of Africa. Most turtles would freeze to death if they
attempted to swim around in those places, but leatherbacks can keep their bodies as
much as 18 degrees warmer than the water they’re in. And understanding how they pull that off can
teach scientists a lot about keeping warm in cold environments. The turtles’ massive size is certainly part
of the answer, as there’s less surface area for heat dispersion relative to their volume. They also have a lot of oil in their bodies,
which acts as insulation to trap any heat produced by cellular reactions. But another part of their secret is a unique
network of blood vessels at the base of their limbs. Lots of animals use similar networks of blood
vessels to conserve heat, allowing their extremities to be a bit cooler. But with leatherbacks, the networks go the
other way — ensuring the turtles’ limbs stay warm. The researchers that discovered this in 2015
think that’s because their overall warmth is dependent on the heat generated by their
muscles when swimming, which requires completely functional flippers. And boy, do they swim a lot. Studies where turtles are marked or tagged
in some way have found individual leatherbacks can travel nearly 20,000 km in less than 2
years. That’s like traveling from one end of the
continental United States to the other seven times. And, remarkably, after all this globetrotting,
females somehow find their way back the beach where they were born to lay their eggs. They seem to keep track of where they are
and where they need to go, but so far, the science behind their mad navigation skills
remains a mystery. Pig-nosed turtles might have earned their
name from their adorable snouts, but their claim to fame isn’t their noses — it’s
their legs. Or, more accurately, their flippers, because
they’re the only freshwater turtle that has enlarged paddles for forelimbs instead
of simpler, webbed feet. The pig-nosed turtle is found in the rivers,
lakes, and swamps of northern Australia and Papua New Guinea. And as the last surviving member of it’s
family, it could hold clues to understanding some of the mysteries of turtle evolution
— like, how the reptiles made their way into oceans. Flippers are considered an important step
towards a marine lifestyle, as they allow for faster and more efficient long-distance
swimming, which matters a lot if you’re swimming across oceans. But… that’s not how the pig-nosed turtle
uses them. Though their front flippers look like the
limbs of sea turtles, they don’t flap them quite the same way, so they’re much slower
and less efficient than their marine cousins. But, they do something really weird with them
that may explain why they exist. Bigger pig-nosed turtles will actually run
along the river bottom using their hind legs while their front flippers are extended to
provide stability and lift. When running this way, they can move almost
as fast as their top swimming speeds. And because they’re not flapping their front
limbs, bottom-running could help them quietly but quickly sneak up on prey. Some biologists think this may be how sea
turtles first got their flippers, too — only later did they develop more efficient ways
to use them. The Chinese softshell turtle has what sounds
like a pretty gross habit: it pees out of its mouth. Ok, it doesn’t emit a stream of urine from
its tongue or anything. But it does use its mouth to secrete urea
— the waste product of protein breakdown that lots of animals, including other turtles,
get rid of by urinating. And understanding exactly how they do this
is helping scientists learn a lot more about how excretion systems work. Herpetologists have always known the turtles
have strange little projections of tissue in their mouths. They thought these were like gills and could
pull oxygen from the water, letting the turtles breathe without surfacing. And, they do do that, to some extent. But more importantly, in 2012, scientists
discovered that they’re covered in urea transporters — proteins normally found in
kidneys — which pump urea out into the turtles’ spit. Because of this, their saliva can have 250
times more urea than their blood. And it’s such an efficient system that the
animals secrete 50 times more urea through their mouths than the usual kidney-bladder
route. But as icky as all that sounds, it’s likely
what made it possible for Chinese softshell turtles to invade salty environments. These turtles hang out in brackish water — water
that is a mix of salt and freshwater. And that’s something most turtles can’t
do because making urine requires a lot of fluids. Turtles generally can’t drink tons of saltwater
because their bodies don’t have a great way of dealing with the salts in it. The only exceptions are sea turtles, which
have evolved special glands for the task. But being able to excrete urea from their
mouths means Chinese softshells don’t have to drink a lot to pee, so they can hang out
in saltier environments. There is a drawback to all this, though — they
don’t have a great way of getting rid of their urea-laden spit if they hang out in
drier places. Basically, they can’t pee enough on land. That’s why Chinese soft-shells don’t spend
a whole lot of time out of the water. And when they do end up on land, they find
whatever puddles they can, dip their heads in, and rinse the out their mouths. The Fitzroy River turtle is a freshwater turtle
found — you guessed it! — in the tributaries of the Fitzroy River in Queensland, Australia. And it might seem like a pretty standard turtle
at first, but it has an incredible superpower — it can stay underwater for days. And, it turns out this turtle gets this power
from its genitals. Turtles reproduce using a cloaca, a single
opening which also connects to the urinary and digestive tracts. A lot goes on in there — and in some species,
like the Fitzroy river turtle, that includes breathing. Special sac-like structures in the cloaca
called bursae basically act like internal gills. As the cloacal muscles contract, fresh water
rushes into the bursae, allowing blood vessels in the tissue to absorb oxygen from the water. Studying these bursae and how they work can
help scientists understand the physical limitations of the endangered turtles, and in turn, what
habitats they need to persist. And it could help engineers design systems
that similarly pull oxygen from water to let people or the underwater vessels they travel
in stay down longer. Now, lots of turtles have these cloacal breathing
sacs, but Fitzroy river turtles have the best in the business. The inner surface of each sac is covered in
papillae — little, branched projections of skin full of blood vessels — which increase
the area for gas exchange by 16-fold. That means the Fitzroy river turtle can take
up a ton more oxygen — young turtles can get 70% or more of the oxygen they need from
their cloacas, so they can stay underwater longer than other turtles. When not hibernating, turtles generally count
their time underwater in minutes. The Fitzroy river turtle can swim around without
surfacing for days at a time — and in cooler, oxygen-rich winter waters, they can stay down
for weeks. In a 2003 study, two of the tagged turtles
stayed underwater for the entire 21-day field experiment. Which is not too bad for what’s essentially
genital-breathing. Or butt-breathing? Cloacas are weird. And there you have it — six of the most
wonderfully unique turtle species out there. Although, really, we could have made this
list go on for days, because there are just so many amazing things that turtles do. They started out-weirding their vertebrate
kin before dinosaurs were even a thing, though now, over 60% of turtle species are threatened
by extinction. But, if we don’t give up on them, we can
all help Keep Turtles Weird. If there’s anything we can learn from these
strange turtles, it’s how successful you can be if you solve life’s problems creatively. And KiwiCo can help you foster that wonderful
kind of out-of-the-box thinking in kids you care about. KiwiCo projects are designed to spark creativity
and confidence in kids of all ages — from infants and toddlers to teenagers. The hands-on projects encourage them to become
makers and idea generators by engineering novel solutions to problems. When you subscribe to KiwiCo, you get a monthly
crate which includes all the supplies needed for that month’s project, detailed, easy-to-follow
instructions, and an educational magazine so you learn even more about that crate’s
theme. All projects are designed in-house in Mountain
View, California and rigorously tested by kids to ensure that they’re educational
and fun. We all want kids to have the confidence to
find creative solutions, because there isn’t one right answer to the problems that arise
in life. By bolstering kids’ self-esteem and creative
confidence, we empower them to change the world for the better. And right now, SciShow viewers can get their
first month of any KiwiCo subscription for free! All you have to do is head on over to kiwico.com/scishow
to get started. [ ♪OUTRO ]
