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Sometimes an animal long thought to be extinct reappears decades or centuries later, shocking scientists! Join Hank Green for a look at seven species that we thought were gone forever... but are back to (hopefully) stay for good!

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Throughout our planet's history, billions of species have gone extinct. In fact, over 99% of the species that have ever existed, don't anymore. Some of them disappeared long ago, leaving behind the occasional fossil to study. Others went the way of the Dodo and were killed off either directly or indirectly by humans. But every once in a while, a creature we thought had kicked the bucket is found ... still kicking. Here are seven animals that turned out to not be extinct after all.
One of the most well known examples of this phenomenon is the coelacanth, a kind of simple fish. Until the 1930s we'd only seen it in fossils, and the fossil record suggested it died off not long before the non-avian dinosaurs did, over 65 million years ago. But then, in 1938, a museum curator named Marjorie Courtenay-Latimer discovered a live specimen someone had fished off the coast of South Africa. These days, we know of 2 different living species of coelacanth, one in the western Indian Ocean, and the other in waters near Indonesia. They've been so hard to find because they tend to live between about 150-250 meters down, in the ocean's twilight zone. Which despite the name, is not a dimension not only of sight and sound, but of mind. It's just pretty dim down there. On top of that coelacanths also gather in caves during the day, only to leave at night to feed. But now that we've found them, we've learned that they're kind of awesome. The coelacanths we've found are nearly identical to fossils hundreds of millions of years old, so they have a lot of anatomical feaures we've never found in modern animals. For example, they have a hunge inside their skull that's unique among all living vertebrates. It allows the back of their skull to swing upwards, so they can basically open their mouths super wide. So basically they'd be perfect dental patients, if they weren't fish. I mean, I don't know... Maybe they have toothe problems. Coelacanths are also the only living fish we know to have seven lobed fins -

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-and we only know of one other living fish with lobed fins at all, the lung fish. Four of the ceolacanths fins are paired up, and they move similarly to how land-based animals night move their legs. Because of this, scientists used to think that the coelacanth could be the so-called 'missing link' between sea and land animals but genetic sequencing has debunked that. The role most likely goes to the lungfish, which is the coelacanths closest relative. But don't worry coelacanths: we still think you're special.

Like the coelacanth, we used to think the Kha-nyou, or Loatian Rock Rat, was long gone. But instead of being found by fishermen, this animal was spotted at a meat market. In the late 1990s, two scientists visitinf Laotian meat markets independently identifed what appeared to be a new species of rodent. The animal, which looked like an adorable cross between a squirrel and a large rat, was a regular on the market menu, but it took nearly a decade to confirm what it really was. In fact, the first ohotographs of a living Laotian Robk Rat weren't captured until 2006. Based on initial DNA testing, scientists first thought the creature was part of a brand new taxonomic family, one most closely related to guinea pigs, African mole rats, and porcupines. But within a year, new analyses revealed that it was actually the only living species from its taxonomic family Diatomyidae, which disappeared from the fossil record around 11 million years ago. Today, the rodent is mostly found in Central Laos, but a smaller population has also been found in Vietnam. Both groups live in the crevices of limestone towers in forests, so that might explain why they're hard to find. Since they're so rare, most of what we know about the species comes from analyzing bushmeat samples and talking to the locals who hunt them but the scientists are pretty convinced that the rodents are nocturnal and mostly herbivores, although they might occasionally eat insects.

If you're looking for and animal we thought was extinct for a really long time, you might want to try out monoplacophorans, a type of mollusk that we thought disappeared around 400 million years ago and then, in 1952, ten live specimens were collected from the seafloor near Costa Rica over 3500 metres below the surface.

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After that researchers realized that Monoplacophorans had actually been found before as early as 1869, but they were all incorrectly identified as limpets, a kind of snail, because of their similar shape. Today we've found about 30 distinct species, and all of them fall into the subcategory Tryblidia. As the name suggests, Monoplacophorans have a cap-like shell with just one plate. In fact, their shell micro-structure and musculature are basically identical to those found in fossils half a billion years old.

But a lot about them, including how they grow and reproduce, and their relationship to other mollusks, is still a big mystery. They're so simple that researchers once believed they could be the original mollusk, from which all others descended, and because they show signs of segmented organs, they were also seen as a potential missing link between all mollusks and annelids, or segmented worms. They probably aren't either of those things though. Newer research suggests that instead of being the OG mollusk they're actually a super-specialized branch on the mollusk family tree, which is only getting more complicated as we learn more about it.

Mollusks might be simple, but they are not the simplest animal on our list. That honor goes to the Neptune's Cup Sponge which was first discovered around 1820 off the coast of Singapore, and was very quickly harvested to extinction - or so we thought.

These sponges could grow to over a meter tall and wide, and their cup-like shape was so convenient that people actually used them as bathtubs for their babies. Because they were so large, they were a valuable collector's item for individuals and museums, and we kept harvesting them until they were almost all gone. The last time anyone recorded a living one was 1907, at least until 2011, when scientists discovered two living specimens in the waters off Singapore's St. John's Island. Before then, in the 1990's, we'd seen dead sponges wash up on shore in Australia, so there was some evidence they weren't extinct after all, but it took over a decade to find these live ones. 

The two sponges were young, only about 30 centimeters in diameter which is nowhere near as large as they could grow to be, but they did teach us that these sponges don't grow as slowly as we used to think.

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The two young sponges grew several centimeters over just a few months, which is a lot compared to other species of sponge, which only grow that much in a year. As of this May, three more live sponges have been discovered and to help conserve the species, they've been transplanted so that they're close enough to each other that they can reproduce. It's safe to say we will not be using them for baby baths anytime soon, or ever, let's not make that mistake again.

The first fossils of the Mallorcan Midwife Toad were found in 1977 on the island of Mallorca in the Meditteranean. Based on those fossils researchers thought it had been extinct for a few thousand years, probably because Romans had introduced predatory snakes to the island. But only three years later, we found live ones.

Midwife toads are not especially talented at helping others through labor or anything, the name comes from how the males care for fertilized eggs - they carry a string of 7-12 of them wrapped around their hind legs until they hatch, like a little tadpole fanny pack. These tiny toads only grow to be four centimeters long, and they used to be found all over Mallorca, but invasive species have pushed them into the northern mountains where they live in small streams carved in the limestone.

Thankfully, active breeding programs across Europe have existed since the mid 1980s, and the first toads bred in captivity were reintroduced to the island in 1989. So far, these conservation efforts have been considered successful, and the toads were even reclassified in 2004 from critically endangered to vulnerable, so things are looking up!

Meanwhile, just east of Australia you'll find the ten kilometer long Lord Howe Island, formerly the home of the creatively named Lord Howe Island Stick Insect. It's also nicknamed the land lobster or tree lobster, depending on who you ask. They are not as big as actual lobsters, but they can grow to be 15 centimeters long, or about as big as your hand, which if you ask me, is bigger than any insect really needs to be.

Either way, we thought they'd been wiped out not long after 1918 when a shipwreck on the tiny island introduced a bunch of black rats that would've considered stick insects a really tasty snack.

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But it turns out that about 25 kilometers away, on an even smaller volcanic outcrop called Ball's Pyramid, a very tiny population survived and we finally found them in 2001! Unfortunately, Ball's Pyramid is not an ideal environment for them. These insects used to live in forests in the hollows of tree trunks but there aren't any forests on the outcrop. Instead, they hide in holes full of plan debris and they can only feed on one plant that grows there: the tea tree which can really be a problematic eating strategy, as pandas found out the hard way. In 2003 2 insects were brought to the Melbourne zoo to begin a breeding program and so far over 14,000 insects have been born there. This year, a new female named Vanessa was brought from Ball's pyramid to the zoo for some much needed extra genetic diversity and she's definitely living her best life. She currently has her own $80,000 climate controlled glass house. But 14,000 insects does not mean a species is saved. With fewer than 30 of them in the wild the Lord Howe Island stick insect is a strong candidate for the world's rarest insect and even though Ball's Pyramid is nearly inhospitable for them, it's not safe to start reintroducing these critters to Lord Howe Island until conservationists take care of the rat problem because there are still plenty of those guys running around so only time will tell if they will ever be able to return home.
Finally, for our last not-dead-yet animal we have the Ecuadorian Horned Anole, or the 'Pinocchio Lizard'. One look at a male specimen and you will see why. The Anles were first discovered in the 1950s, but the few scientists could find were all male so they couldn't tell if the females also supported that impressive nose and, within a decade, all signs of them had vanished. their suspected extinction was probably caused by deforestation, since the Anoles were only found within about 250 square kilometers of forest near the village of Mindo. But in 2005, a group of birdwatchers travelling through the area saw a single, strange lizard crawling along a road. They caught it

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and snapped some photos and it was identified ans the long-lost Ecuadorian Horned Anole. several years later, scientists captured specimens for study. They had to go at night because these Anoles are super well camouflaged during the day and they ike to hang out high up in the trees and creep around very slowly. But at night they change color and become pale enough that flashlight can pick them out amongst the foliage. So far, we don't know why they do this but it is convenient at least. Even though we know they're alive now, researchers still don't know much about these lizards. They can actually wiggle their proboscis but scientists don't know exactly how they do it. They might have muscles in their snouts, which would make them different from other lizards. Or maybe their bodies pump fluid into and out of them. If nothing else, researchers are pretty confident that the proboscis is used for mating displays, as opposed to like fighting other males. Thats partly because they're super flimsy and would make for terrible nose swords, but also because of directly observing males flourishing them around before getting it on with their partners. We, or course, don't know exactly how many Ecuadorian Horned Anoles there are, but so few have been spotted that they are listed as an endangered species. Hopefully we can keep them and their habitat around long enough to get some answers. No matter what the pressures on these organisms that have pushed them so far out of our grasp that we just thought that they were gone, it's always an exciting moment for science when a species seems to come back from the dead. Some of them act like little time capsules from Earth's past and all of them help us better understand the family tree of life. And hopefully we will be able to keep them alive and well for years to come.
Thanks for watching this episode of Scishow! If you love learning about what life used to be like on earth including about some animals that did go extinct you can check out our new sister show Eons over at It's so good. I'm loving doing it. I - just the scripts are so - thank you to all the writing staff there. It's been such a wonderful journey into the marvellous and humongous history of life on Earth!

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*Outro Music*