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It could be the next blockbuster sci-fi movie. Imagine a creature that reproduces by having
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up to 100 of her own eggs pressed into her back. Her skin then grows up and around the
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eggs, where they incubate until hatching. When they hatch, the babies stay there for
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up to four months, eventually bursting through pockets in her back, leaving large holes all
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over her body. Even though a hundred fully formed beings have emerged, the mother doesn't die
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She continues to give birth in this horrific manner again and again and again. And as if all
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While that wasn't horrifying enough, as the babies are born, they might engage in some
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light cannibalization of their siblings. None of this is science fiction. Just science
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This is the actual reproduction method of the Suriname toad, a small amphibian native
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to South America and parts of the Caribbean. Why does this tiny toad give birth in a manner that David Cronenberg would find inspirational
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Evolution, of course. It's much harder for predators to find and eat toad babies when they're basically growing
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under mom's skin. Hi, I'm Erin McCarthy, editor-in-chief of Mental Floss, and this is The List Show
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The Suriname toad's unique method of childcare isn't even the weirdest animal evolution
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we're going to discuss today, so let's get started. Let's stay amphibious for a minute and talk about the axolotl
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Arguably the most adorable of all salamanders, the axolotl is fascinating for many reasons
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First of all, axolotls are a bit of a biological anomaly because they're neotenic, meaning
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they keep juvenile traits even when fully mature. In this case, the axolotl retains gills and remains aquatic for its entire life, unlike
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other salamanders. In fact, in the 1860s, scientist Auguste du Meriel experimented with inducing maturity
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by cutting off the axolotl's gills. The gills simply grew back. This isn't too surprising
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You might already know that many salamanders, axolotls included, can regrow their body parts
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an evolutionary trait that, especially for axolotl, scientists believe grew out of cannibalism
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And yes that our second cannibalism reference in less than three minutes With the Suriname toad baby axolotls tend to snack on each other Instead of letting that slow them down though they simply regenerate new limbs It takes just weeks to regrow an entire arm or leg in the exact right size shape and orientation
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But while other salamanders can also perform this specific magic trick, the axolotl has an extra ace up its sleeve, the ability to regenerate parts of its brain
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As you might suspect, researchers are very interested to know how and why this phenomenon
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occurs, so we might someday be able to use the same principles in humans. We're not there yet
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but here's hoping the axolotl shares its evolutionary secrets with us. The jerboa is an adorable bipedal rodent with ridiculously oversized ears and legs
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native to deserts and steppes from East Asia to North Africa. One species, the aptly named
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long-eared jerboa, has ears about two-thirds as long as its body to help the critter release heat
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and stay cool. The animal's hind legs may look spindly, but the shape and structure of the bones
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mean that some Jerboa species have a reported three-foot vertical. This unique feature allows
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them to easily escape their many predators, which appears to be a fantastic evolutionary advantage
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But whereas the smallest of the Jerboa species have separate bones in their feet, like humans
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others have partially fused bones. The largest of the species is also the most recent iteration of
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the Jerboa lineage. It has completely fused foot bones. That's why the Jerboa is actually an example
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of how evolution may have outkicked its coverage. Interested in how the metatarsal fusion had
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evolved across the species over time, researchers at the University of Michigan created 3D models
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of each type of bone and performed exhaustive stress tests on all of them. The unfused bones
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number one on the evolutionary journey, performed the worst. Number two, the partially fused bones
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did the best. The completely fused bones, the newest evolution, did second best. That evolution
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should have stopped at the optimal partially fused bones, but since the fully fused bones still got
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the job done, there was no pressure to stop fusing. This phenomenon is known as evolutionary overshoot
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Why does it matter? Well, the researchers conducting the studies included engineers and an assistant professor
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of robotics The ideal Jerboa foot could eventually lead to the creation of a robotic leg better designed for withstanding higher forces At first glance the saiga antelope kind of looks like it should be moonlighting at the Mos Eisley Cantina Known for bulbous noses that drape down over their
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mouths, these small herbivores are found not in a galaxy far, far away, but in Mongolia, Russia
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Kazakhstan, and Uzbekistan. Their unusual noses are incredibly complex, lined on the inside with
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hair, glands, and mucus tracks. Its nostrils are actually sacs lined with mucus membranes
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As for why, the main theories are some combination of allowing the Saiga to warm up cold air and
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or filtering dust. Unfortunately, this cool evolutionary trait also nearly killed the Saiga antelope. In
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2015, more than half of the population was swiftly and suddenly wiped out by a disease
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and their numbers were already dwindling due to poaching and interruption of their migratory
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route. Scientists later determined the cause was hemorrhagic septicemia, caused by a bacteria
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that is naturally present in the unique noses of the saiga. The conditions that year—humidity
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unusual warmth—caused the bacteria to grow out of control. But don't worry, there's good news
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Thanks to anti-poaching measures and a newly protected habitat, these days, saiga antelope
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numbers have soared to nearly 2 million, bumping them from critically endangered status to near
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threatened. At just 6 inches long, the yeti crab is certainly less intimidating than its cryptid
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namesake, but it's also known for surviving some pretty extreme conditions. The Yeti crab was discovered in 2005 at the bottom of the Pacific Ocean. Researchers found
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it chilling out in a rather peculiar place, 7,500 feet deep between blazing hot hydrothermal
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vents and the freezing cold ocean floor. Even stranger, their claws were covered in shaggy
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bristly, hair-like structures called siti. The following year, another species of Yeti
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crab was discovered in what's called a cold seep near Costa Rica, and this particular kind
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liked to wave their fuzzy arms in the air like they just didn't care. Turns out there's an evolutionary explanation for the fluff and the dancing
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While the CT may seem like a trait developed to ward off the extreme cold like little evolutionary mittens they actually use them to grow nutrient bacteria The crab uses a hairy mouth appendage to scrape the bacteria off and eat it It believed the dancing helps to stir up nutrients and oxygen in the water which helps the bacteria grow
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In 2010, yet another version of the yeti crab was discovered, this one with fur on its chest and
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belly area. Scientists informally dubbed it the Hoff Crab, an homage to Baywatch star David Hasselhoff
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We couldn't talk about evolution without discussing the duck-billed platypus, one of nature's most fascinating mashups. It has a bill that looks like a duck, of course
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a tail like a beaver, feet like an otter, and lays eggs like a reptile, even though it's actually a mammal that produces milk. And oh, did we mention that the males are
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venomous? Together, it's a collection of features so odd that when the first taxidermied specimen
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was examined in 1798, scientists believed it was Frankenstein together from multiple animals
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For years, researchers have wondered which platypus features are inherited from its
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reptilian ancestors and which are the result of evolution. When they were finally able to decode
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its genome in 2008, they got a few answers. They found genes for egg yolk protein usually
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only found in reptiles and fish, meaning that the egg-laying trait was inherited, not evolved
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The ability to produce venom does resemble other animals, but all of them probably evolved venom
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separately using the same genetic toolkit. The electroreception in their namesake bills helps
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them detect prey underwater, another trait that was probably evolved. But while we unravel some
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mysteries about this curious creature, new ones continue to pop up. In 2020, scientists discovered
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that platypus fur is biofluorescent. It glows under UV light. At the time, this was dismissed
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as just another weird platypus story, trademark, but that discovery spurred further research
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According to the New York Times, the Western Australian Museum started to shine a UV lamp at
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random animals in their collection. From koalas to house cats, they were finding biofluorescence
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So not only does the platypus throw up questions about itself, it's throwing up questions about
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all mammals. And in case you were wondering, which you definitely were, it has been shown that humans
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with unpigmented hair are biofluorescent as well. Those are all of the wild animal evolutions we
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have for you today. Thanks for watching and I'll see you next time
