When Evolution Gets Weird

this episode was brought to you by Skillshare hey everyone I am just kidding and you're watching Animal Logic second-nature understandings are first gained by seeing things at first and watching experiencing metamorphosis metamorphosis when one thing becomes another [Music] when we talk about growth we usually think of growing up metamorphosis but the long road of growth is not just up if it were it would mean that this little baby would someday look like this [Music] this process is a truly mind-boggling phenomenon ensured by over 65% of all animal species on earth the majority of which are insects insects developed from young to adult in three different ways they all start from eggs of course silverfish illustrate the first method the young are much like the adult except in size there is no metamorphosis so many insects undergo metamorphosis that it would be easier to count those that don't than those that do to common insects you may be unlucky enough to see regularly that don't metamorphosize our silverfish and bristle tails there are two broad categories of metamorphosis complete and incomplete incomplete metamorphosis which means no basic change in structure from them to adult incomplete metamorphosis is when an insect changes in several stages called instars or nymphs depending on the species these changes are often very gradual and some species can have up to 15 nymphal stages they start as eggs then they hatch and at the end of each stage they molt during molting the insect separates from their cuticle their equivalent to skin they begin to secrete materials that will form their new cuticle while their old one eventually disintegrates and they break out of it they're soft at first but their new cuticle hardens up within a few hours during this process they gain new features cockroaches and crickets for example gain wings through molting and their sexual organs only become functional after their final molt the young called the nymph has no wings it gets wings in its final mode because of this gradual development adult insects that undergo incomplete metamorphosis tend to look like their babies but with extra features like a pokemons final form except for maybe Magikarp complete metamorphosis is where things start to get really interesting complete metamorphosis shows four distinct changes from egg to adult the cycle starts when for example an adult Mexican bean beetle lays a cluster of eggs species that undergo complete metamorphosis go through four distinct phases egg larva pupa and adult each one of these life stages serves a specific purpose the goal of a larva is deed as much as possible so that it can grow and develop while the goal of an adult is to reproduce in fact in some species the adults don't even eat they spend their entire adult lives trying to reproduce fueled by the energy store by their larval stage Goliath beetles can live for up to two years in the larval stage and get particularly swole in preparation to pupate now this one is 33 grams exactly now the adults generally lay their eggs near a food source so that when they hatch the larvae can quickly begin to stuff themselves with as much food as they can eat as they grow they molt and once they've developed enough they pupate when all of the black widows eggs have been eaten the maggots pupate during this stage they develop into their final form adults some insects like moths form cocoons out of silk or poop to protect themselves as they go through this radical change butterflies on the other hand don't form protective cocoons and instead their exterior forms a hard chrysalis [Music] and like butterflies they can be breathtaking some even look like gold the chrysalis is arresting stage during which the animal changes into a beautiful butterfly during the stage the larvae release enzymes that dissolve their own tissue once broken down the adult structures begin to form out of tiny clusters of cells called imaginal discs these imaginal discs are cells that are present when the larvae are born they are attached to their epidermis by a thin stalk and remain dormant throughout their larval state though once awoken during the pupil stage they go to work what they're able to do is almost too fantastical to be true once they're activated the cells begin to divide very quickly to make more cells eventually building entire structures like wings in just a few days even more fantastical is the fact that these elements are developed independently of one another and then attached later so a wing may be grown in one area and then moved into place somewhat like assembling a car you don't have to build each part where it's going to end up so a lake could be formed near the head and then move down to its thorax even even more fantastical is the fact that some butterflies can remember things from when they were caterpillars a caterpillar is a growing upstaged in the life of a moth or butterfly a group of scientists did an experiment where they would emit a particular smell and then administer a small shock to a caterpillar the caterpillar would learn to avoid the smell in the future but the surprising thing is that after the caterpillars went through their metamorphosis in which their bodies are completely dissolved and reformed when presented with the same smell the adult moths would freak out [Music] this suggests that parts of their nervous system have continuity through their radical body change by the way do you know how to tell a butterfly from a box well the best way is to look closely at the animals and penny or feelers roughly 98 percent of all insects undergo metamorphosis but it wasn't always this way for millions of years a metabolic animals or animals that don't metamorphosize reign supreme these early insects hatched as miniature versions of the adults but that all started to change around 300 million years ago when a new player emerged these new insects hatched with bodies that were radically different than their adult forms not only did they look different but they behaved differently - they different food and occupied different niches soon they started to change their shape to best exploit the resources for example some newborns began to look more like worms in order to dig better and find meals underground while the adults became larger and evolved tools for defense against predators better vision for flying color vision to find the tastiest food and so on since insect generations are so short new adaptations can evolve very quickly eggs begin to hatch earlier and earlier these pre nymphs got better and better at fending for themselves and didn't need to stay in the egg as long these became known as larvae though despite how adept these new larvae were at finding food and surviving inside the egg they still lack the sexual organs they needed to reproduce instead of a slow gradual transformation gaining sexual organs as they matured these insects underwent brief periods of accelerated change what we now know as few patient with their various life stages able to dominate different niches a metabolic insects who could only specialize in one area and had to compete with their own young for survival were pushed out of the market insects aren't alone amphibians and some fish also undergo metamorphosis frogs salamanders and all other amphibians can live on land but they lay their eggs in the water the adult toad spends most of his life on land but when spring comes he returns to the pond for the mating season when the eggs hatch the babies emerge with external gills and some fish like features like fins and a lateral line an organ that detects vibrations in the water and changes in water pressure frogs and toads begin as tadpoles and as they grow their legs appear under their Gill sacs and their mouths become larger they start to transition from vegetarian to carnivore and their intestines lose 75% of their length as a result they lose their lateral line and instead develop binocular vision which gives them depth perception their tails stay around a bit longer than the rest but ultimately are lost depending on the species this transition from legless vegetarian swimmers to hopping carnivorous amphibians can take between two and eight months to complete [Music] some salamanders like the axolotl don't undergo a full metamorphosis and stay in their aquatic form instead retaining their external gills throughout their lives amphibian metamorphosis is controlled by a single hormone called pyroxene and we still really don't know how it works this single hormone tells tale muscles to die tells limbs to grow tells intestines to shrink and makes lateral lines completely disappear all that from a single hormone I'd like to know more about different kinds of hormones some species of fish also undergo metamorphosis controlled by thyroxine though not nearly as many fish metamorphosize as insects as their environment doesn't change all that much that said the fish that do change change their strategies as they mature flatfish are born symmetrical and swim around like regular fish but as they age their eyes slowly start migrating to one side of their head so that they can eventually stop swimming and spend the rest of their lives on the ocean floor eels have four stages of metamorphosis and their larvae are hands down the most mesmerizing larvae in the animal kingdom in some species they can stay at this stage for over two years looking for nutrients as they grow and develop salmon undergo metamorphosis because they are in a dermis they battle their way upstream against Swift currents seeking quiet waters where they may straw [Music] their lives begin in fresh water then they go out to sea and finally they return to fresh water to spawn and die they start out as elephants during this stage they survive off a yolk sac that is attached to them out of the egg when they finish the yolk they swim to the surface fill their swim bladders with oxygen and begin to look for food in this stage they're called fries as the fries migrate to the ocean they get larger grow scales and turned silver they mature in the ocean before returning to the stream from whence they came they stop eating and begin to make the struggle upstream once they've reached their destination the male's develop a hook nose to fight each other for mating rights after they spawn they die metamorphosis is how most things on this planet get by yet despite this it's far too fantastical to describe it as common the astonishing change that takes place in this phase of a life cycle is known as metamorphosis I'm new around here so I thought I would take a really quick second to introduce myself a little bit more I'm just kidding and yes I get just kidding all the time I'm a zoologist illustrator and author I've written eight children's books so far with five we're on the way all about science nature animals and badass women in stem and I'm so happy to be hosting Animal Logic second-nature along with Danielle one question I get all the time is what's the secret to writing the bad news is there is no secret it just takes a lot of practice you just need to keep writing and if you're having trouble getting started a great place that I found to get motivation as well as tips tricks and insights from professional authors is Skillshare one of the best writing courses I've seen on Skillshare is storytelling 101 created by Daniel Jose older a New York Times bestselling author this very well produced course will leave you with the framework for writing your own fictional short story whether you're just starting out are you been writing for years this course is meant to help you hone your skills focus your storytelling and inspire you to put pen to paper it's quick fun and it's giving me some great strategies for helping me deal with writer's block Skillshare is an online learning community with over 25,000 classes in writing illustration production and a whole lot more Premium Membership gives you unlimited access to high-quality classes on must know topics so you can improve your skills unlock new opportunities and do the work you love join the millions of students already learning on Skillshare today with a special offer just for animal logic fans two months of Skillshare for free to sign up go to the link in the description and the first 500 visitors will get two months of unlimited access to over 25,000 classes all for free act now for the special offer and start writing today so what should we talk about next please let us know in the comments down below and do not forget to subscribe for new episodes of Animal Logic second-nature every other week thank you so much for watching the principles of growth and development we've seen in this film apply to all human beings now let's begin our discussion by answering the first question from the preview committee who can tell us when human growth begins [Music]

Channel: Animalogic

Views: 2,666,968

Rating: 4.8897243 out of 5

Keywords: animals, animal, logic, education, show, animalogic, crazy, ugly, weird, gross, beautiful, interesting, facts, animalsfacts, about, information, info, school, research, learn, learning, fun, easy, smart, metamorphosis, pokemon, evolution, caterpie, insect, amphibian, butterfree, axolotl, tadpole, frog, nymph, change, timelapse, chrysalid, chrysalis, gold, golden, cocoon, moth, caterpillar, salamander, evolve, train, real-life pokemon, real-world pokemon, salmon, flatfish, time, lapse, time-lapse, wasps, secretary bird, #secondnature

Id: EdFJOkaI80g

Length: 15min 19sec (919 seconds)

Published: Mon May 20 2019

Reddit Comments

[u/[deleted]]

Very nice! Good video on a topic I don't usually think about