00:00Now, sloths can hold their breath longer than dolphins.
00:03Yep, incredible, but true.
00:06They slow their heart rate so much, they can stay under the surface for up to 40 minutes.
00:11Unlike fish, dolphins and whales are aquatic mammals, which means they can't breathe underwater.
00:17When it comes to breathing, they're more similar to us than the fish.
00:21Both of them have lungs, and they breathe air through something we know as a blowhole.
00:25When they're under the surface, they hold their breath until they come up for some air again.
00:30Dolphins can stay under the water for 10 minutes.
00:33A sperm whale can hold its breath for 90 minutes,
00:36while an elephant seal holds the record when it comes to aquatic mammals
00:40and can stay under the water for 2 hours without having to go up.
00:45There's a wasp so tiny, much tinier than its name, it's smaller than an amoeba,
00:51even though amoebas are made of one cell only.
00:53You can see this wasp has the same body parts as the rest of the bugs – wings, brain, eyes, and the rest –
01:00but it's really a tiny version of an insect, since it's only 8 thousandths of an inch long.
01:07And the smallest adult insect we know of is a parasitic wasp with a big name, also known as the fairy fly.
01:15Their males don't have wings, they're blind, and only 5 thousandths of an inch long.
01:19Now, it's no coincidence each animal species has different colors and patterns.
01:25One of the reasons for that is to help them stand out when looking for their potential mating partners,
01:30or to send a warning to predators they're poisonous and hope they get the message right.
01:35Then, there are ambush predators, such as tigers.
01:39It's very important for them to remain invisible, because the difference is huge.
01:43If their prey sees them before they get there, no dinner that night.
01:48But why exactly are tigers orange?
01:51For us, orange is a color used for things that need to be ultra-visible.
01:56For example, items such as safety vests or traffic cones.
02:00To the human eye, orange will mostly stand out in the environment.
02:04So, if there's a tiger coming for you, you'll spot it relatively easily.
02:08But humans have so-called trichromatic color vision.
02:13When light from your surroundings enters your eye, it hits the retina, a thin layer located in the back.
02:19To process that light, the retina uses two kinds of light receptors, rods and cones.
02:25Rods can only distinguish differences in light and darkness.
02:28They can't sense color.
02:30Our eyes will mostly rely on rods in dim light.
02:34Cones are in charge of color perception.
02:36Humans mostly have three types.
02:38Cones for green, blue, and red.
02:40That's exactly why we call our vision trichromatic.
02:44Most humans see three primary colors, together with their colorful combinations.
02:49Apes and some monkeys also have such a style of vision.
02:53But most mammals that live on land, including cats, horses, deer, and dogs, have dichromatic color vision.
03:01Retinas in their eyes have cones for two colors only, green and blue.
03:05When humans get information from their green and blue cones only, they're considered colorblind since they can't, for example, tell the difference between green and red shades.
03:15This is similar with mammals that live on land.
03:19Deer are surely tigers' prey way more than humans.
03:22And deer don't see tigers as orange, but green.
03:25Green tigers would surely be more difficult to spot, which would mean more dinner for tigers.
03:32But evolution still decided to go with orange because it's simply easier to produce such a color.
03:38The only green mammal is a sloth, but its fur is not naturally green.
03:43It's because of the algae that grows in it.
03:45And they can hold their breath for 40 minutes.
03:48The water around the poles can get very cold during certain periods of the year.
03:53There's plenty of fish that live there, but when that happens, they need to swim away to survive.
03:59But there's a special group of fish native to the southern ocean near Antarctica.
04:05The temperatures there are from 28 to 39 degrees Fahrenheit.
04:09Technically, that's below freezing, but all those dissolved salts in the seawater don't allow it to freeze over.
04:15And these fish can survive because they have a special feature called glycoprotein.
04:21It helps them stay in their home because it acts as sort of a natural antifreeze.
04:26It's a protein that prevents all those ice crystals from forming in their blood and helps it continue to flow normally.
04:33Have you ever wondered how tiny animals like ants breathe?
04:37Try to open your mouth and throat, but at the same time, hold your chest and diaphragm still.
04:42The diaphragm is a muscular structure that separates the chest and abdominal cavities in all mammals.
04:49It expands as you breathe.
04:51If you can't do this, you can't hold your breath, because oxygen will still find its way into your lungs.
04:57At least, enough of it to keep up with your body's demands.
05:01But generally, when you breathe, diaphragm is actively pumping air in and out of your body.
05:07To survive without the diaphragm doing so, you'd need more than one throat and a way smaller body.
05:14Now, ants have 9 or 10 pairs of openings along the sides of their tiny bodies.
05:20They're called spiracles, and each is connected to branching series of tubes.
05:25It's a system similar to human lungs.
05:27Their blood doesn't carry oxygen from those tubes to the rest of the body.
05:31Instead, the tubes spread this oxygen.
05:34The endings of these branches directly touch the membranes of their cells.
05:39This can only work in really small animals.
05:42When the body is bigger than 8 tenths of an inch, these tubes are too long, so they can't diffuse air fast enough.
05:49There are a couple of reasons why giraffes have long necks, which, by the way, can grow up to be 6 1⁄2 feet long.
05:57From first glance, it seems evolution gave them those to reach the sweetest, topmost leaves of the trees.
06:04It's exclusive access other animals can only dream of, so giraffes don't have to compete for the best bites.
06:12But over time, researchers realized it's not the only reason.
06:16They also think the neck could be a good factor when male giraffes go into combat.
06:21The same as male antelopes will use their prongs or when a stag uses its antlers.
06:27The thicker the neck, the bigger the chances to win the combat.
06:32Some insects play possum when there's a predator nearby.
06:36For instance, in one research, scientists have observed an ant-lion larva insect.
06:41It played possum for 61 minutes.
06:44How does this even help?
06:45Well, let's say you're in a garden where you see a bunch of identical bushes with soft fruit.
06:51You go to the first bush and start collecting and eating fruits.
06:54Mmm, yummy!
06:55It's so simple!
06:57And you're doing it relatively fast.
06:59But as you strip that bush, it's getting harder for you to find more fruits.
07:04Plus, it's kind of irritating because it takes way more time now than at the beginning.
07:08So, now you need to decide whether to stay there and try to find more, or simply switch
07:14to another bush to have it all easy and fast once again.
07:18Assuming you are the predator, and predators are greedy, you'll just look for ways to eat
07:23as much fruit as possible in the shortest period of time.
07:27This means you'll go on and start collecting fruits from another bush, and the next one,
07:32and so on.
07:33Researchers use the same logic when it comes to bird and ant-line larvae.
07:37It appears that insects waste the predator's time when playing possum, which has a significant
07:43impact on how things go later.
07:46That way, they encourage the predator to look for food elsewhere, because the predator doesn't
07:51have that much time to waste.
07:53So, pretending to be not alive is actually a good way to stay alive.
07:58Depending on the species, young birds spend from 10 to 30 days in their eggs.
08:03There's no air inside, but Mother Nature created a perfect mechanism for them to still be able
08:09to breathe.
08:10As a young chick is developing inside the egg, it grows some kind of hollow, sack-like structure
08:16from the gut.
08:17It's like a tiny pouch that fuses with a second membrane that goes around the chick and its
08:23yoke.
08:23So, one end is attached to the chick, while the other is close to the inner surface of
08:28the egg shell.
08:30That way, this special membrane acts like lung tissue and connects the outside world with
08:35the chick's circulatory system.
08:37Most animals have two eyes, but some species need more.
08:42For example, some reptiles, amphibians, and fish have a third eye on top of the head.
08:48It's not something that improves their vision that much, but it simply helps them navigate
08:53via the sunlight and regulate their body temperature.
08:57Many invertebrates have more than two eyes.
09:00Most spiders have eight of them, because that way, they can spot their prey easier.
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