9 of the Most Abundant Animals on Earth

animals seem to be everywhere. Like, when you meet one pigeon, there’s
probably hundreds more around the corner. It hardly seems fair when there are only a
few thousand tigers in the whole world. But how can so many of certain animals survive? The food chain, usually called a trophic structure
by ecologists, describes where different living things get their energy, and if they provide
energy for other organisms by being food. Plants and some microbes, for example, use
energy from the sun to produce their own food. Then, they’re eaten by small consumers,
which are then eaten by larger predators. Each of these groups is a part of a different
trophic level, and only a fraction of the energy gets passed up to the bigger consumers. In other words, top predators like orcas probably
aren’t going to overrun the planet. And the most abundant animals are usually
near the bottom of the trophic ladder, eating really common foods, living in lots of places, and sometimes even taking advantage of us humans. Of course, there are way too many of these
guys to actually go out and count them, so scientists have to make educated guesses. But here are 9 animals that we’re pretty
sure have huge populations. Even though city pigeons seem to be everywhere, their numbers pale in comparison to other birds. Like the red-billed quelea, which might be
the most abundant wild bird in the world. Despite looking like cute little finches with
bright red bills and carefully-woven nests, they strike fear into the hearts of farmers. There’s an estimated 1.5 billion red-billed queleas across about two-thirds of the African continent. They travel around in flocks of millions that
have been known to crush trees when they roost for the night. One reason they’ve been able to become so
abundant is their diet: they eat all kinds of seeds. And there are lots of seeds out there. Especially since human farmers are in the
business of growing grains. Flocks of queleas can descend on grain fields
like a plague, each bird eating 12 grams of seeds per day. Needless to say, they’re considered to be
a huge agricultural pest. When there’s lots of food around, queleas
can breed multiple times in the same season, which keeps their populations growing. And because they’re so abundant, red-billed
queleas make up a huge part of their trophic level’s biomass, and have a lot of natural
predators and scavengers that eat them for energy. Even though we don’t go down into the deep
sea very often, there’s a whole lot of life down there. In fact, the most abundant vertebrate on Earth
is a fish you probably haven’t run into: the bristlemouth. Fish belonging to the genus Cyclothone, and
others of the bristlemouth family, are estimated to exist in trillions, maybe even quadrillions. Bristlemouths in this genus are tiny, bioluminescent deep-sea fish that have spiky bristle-like teeth. And they get eaten by bigger, scarier deep-sea
fish. We don’t know much about them because they
live pretty deep down, up to about three miles. But we do know that the ocean is big, and
may account for 99% of the Earth’s habitable space, or biosphere. So if schools of bristlemouths can live pretty
much anywhere in the oceans, up to a certain depth … well, that’s a lot of fish. It’s hard to be completely sure what the
most numerous amphibian is, because most species are scattered across lots of habitats. But it’s most likely a frog. One species that’s doing particularly well
is the African clawed frog. They’re tough little guys, and they can eat anything they can find, from live insects to fish to chunks of organic waste. Plus, they can live in just about any pool
of water, and find ways to thrive in all sorts of places, despite different climates. Even though these frogs are native to the
African continent, humans have introduced them across the world. The reason? Pregnancy tests. At some point around the 1940s, scientists
discovered that if you inject a female African clawed frog with the urine of a pregnant person, the frog would lay eggs. Super weird, but pretty nifty. So humans started breeding these guys in a lot of countries, in labs and eventually as pets. Around the 1960s, less … alive … pregnancy
tests were invented, which were smaller technologies that screened for certain hormones. So lots of these frogs were turned loose. Some scientists use African clawed frogs as
laboratory models in research even today, but there are plenty of wild ones chilling
in ponds all over the world. The most abundant mammal on the planet might
be us, at 7 billion and some. But humans don’t fit the usual rules and
survival strategies. There are some mammals that do fit into more traditional trophic structure, though, and that have taken advantage of us. Like the house mouse, which is the reason
we have cats. Some estimates say there are as many house
mice as humans in the world. They breed quickly and eat any food we keep
around, especially grains, and even things like glue or soap. With humans settling all over the world, bringing
food with us and planting crops, it was easy for these mice to come along for the ride. Anywhere we live, house mice can too. And they love to set up shop in the nooks and
crannies of buildings, meaning we provide extensive habitats for them too. We may consider them pests, but they were
pretty shrewd to get in on the ground floor of the whole “humans taking over the planet”
thing. The most abundant mollusc, which is the phylum
that includes the squid and octopus, plus lots of shelled creatures, has to be a snail
or slug. And one possible candidate is the brown garden
snail. These snails are native to Europe, and are food for lots of small predators, but humans have introduced them to all continents besides
Antarctica. Sometimes it was by accident, the little guys
like to stow away on all kinds of plants, which are their main source of food. But other times it was on purpose, because
people like eating them too. Escargot, anyone? Garden snails have done pretty well in spite
of hungry humans, though. They’re considered an agricultural pest,
because they’re good at settling down anywhere there’s moisture and plants they can
eat. Which is … a lot of places. Now, let’s get into the arthropods, which
is a phylum of invertebrates that puts every other animal group to shame in terms of sheer
numbers. Of the insects on Earth, ants outnumber all
the rest, with estimates of trillions of them worldwide. And of the thousands of species of ant, one
of the most abundant is the Argentine ant. The Argentine ant is native to South America, but they’ve hitchhiked on human cargo shipments to every continent except Antarctica. Ants are social animals, and Argentine ants
are especially good at settling down in huge fast-growing colonies, thanks to many breeding
females instead of just one baby-making queen. Some colonies even stretch for hundreds or
thousands of kilometers down coastlines in the Mediterranean, western Japan, and in the U.S. state of California. These ants can take advantage of all kinds
of food sources, and have been known to farm other insects, like aphids, that produce sugary
honeydew. Because of sheer force of numbers, these ants
are tough. And we’ve accidentally brought them all
around the world. These next animals, called springtails, used
to be considered insects until recently. So they get their own category. They’re six-legged creatures, named for
a special springy organ that lets them jump away when they feel threatened. Springtails feed on all kinds of fungus pieces
or rotting dead stuff using internal mouthparts, instead of external chewing bits like insects. Basically, they’re tiny, and researchers
think that they live in soil all over the world – up to tens or hundreds of thousands
of them per square meter. And that includes snowy places, where you might notice the snow flea as a little black speck. These snow fleas can survive temperatures
lower than most arthropods, by producing a natural antifreeze-like protein to keep their
tissues from getting damaged by the cold. So, since springtails are pretty much everywhere,
they’re important parts of ecosystems and a stable food source for anything that eats
tiny invertebrates. As for crustaceans, krill are the poster child
for abundance in the ocean’s trophic structures. Of particular note, the Antarctic krill pretty
much support the entire food chain of the southern oceans, with an estimated population
of around 500 trillion. Dense swarms of small Antarctic krill can
stretch for kilometers and even make the water look orange. They feed on phytoplankton, and are nutritious
meals for basically everything in the cold ocean waters, like whales, penguins, seals,
and fish. And the biomass of all these krill is estimated
to be huge, hundreds of millions of metric tons, which means that they could outweigh all the humans on the Earth. And that’s kind of mind-boggling, since one
human weighs a lot more than one krill. But one crustacean outnumbers every single animal on the planet, and maybe even all multicellular organisms. I give you the copepod, a humble zooplankton,
which are tiny animals that drift around in watery environments. Some of the world’s most important fisheries
depend on copepods of the genus Calanus. Like krill, they live in huge groups, eat
phytoplankton, and provide nutrients to the rest of the food chain. But copepods are better survivors than they
seem: While many ocean creatures are filter-feeders,
eating whatever’s floating in the water nearby, some copepods can detect phytoplankton
at a distance and actively attack them. And even though lots of things eat them, they
can make speedy escapes from predators. Finally, copepods are good at meeting up and
making babies, instead of just drifting in currents and reproducing asexually like many
other small organisms. Sexual reproduction on a regular basis gives
them an evolutionary edge, keeping them ready to change and adapt. If we can learn anything from copepods, and all of these abundant animals, it’s that being near the bottom of the food chain isn’t
so bad. That way, they have plenty of food, can take
advantage of bigger creatures like humans, and spread out across the world. So we tend to think that huge predators like
tigers are really good at what they do, but these little guys seem to have it figured
out too, and are really important parts of ecosystems. Thanks for watching this episode of SciShow, which was brought to you by our patrons on Patreon. If you want to help support this show,
go to patreon.com/scishow. And don’t forget to go to youtube.com/scishow
and subscribe!

100 thoughts on “9 of the Most Abundant Animals on Earth

  1. Though she's far from being classically beautiful and with good body shape, for some reason I think Olivia is extremely hot, especially, when she's talking. I don't know, maybe it's because she's so intelligent? Anyways, I'd definitely hit that.

  2. Does anyone else get a feeling that Olivia’s cadence is like she was just pulled in from the street and told to read cue cards

  3. Wait, how did they found out the pregnancy test thing?

    Was there someone just injecting random urine into random animals?

    Has this person been stopped jet?

    I want answers

  4. You can tell the buttholes from the non-buttholes because they recognize that watching the video has less to do with the actual list and more to do with learning cool-ass facts about different organisms. So they actually watch the video rather than look in the comments for the list from the title.

  5. Olivia would be a fantastic lecturer, she delivers information without being dry. She reminds me of my favorite professor in college.

  6. Where is all this talk of people making fun of her coming from? I literally never see that at all. Most of it is “you’re so beautiful olivia, marry me, have my children.” There’s a few trolls, yes, but the other commentators have to deal with the trolls too, lmao.

  7. Great teller! Thanks for not looking all over excited for being in this video; I can't stand to see someones ego feelings shine through like a sun while talking about or describing a subject.

    Thanks again for being only informative!

  8. Her enunciation is so crystal-clear that you can understand her well even at 2.0 speed!! Can't say that for many folks, that's for sure. Not only that, but at the risk of sounding sexist, she is just SOOOOOOOO cute and adorable – makes learning much easier, lol!!

  9. Is it weird that I find this girl highly attractive? Lol something bout smarty pants chicks like dis..I want her to show me what that brain do…

  10. Look how young and Twitchy she is no no don't get me wrong that's not a bad thing it's just cool to watch everybody grow up on this channel

  11. I miss my African clawed frog. Got her by accident in kindergarten class and she lived till I was in sixth or seventh grade. I’d go into more about how I got her but doubt anyone cares lol.

  12. This is fantastic. I want to know more about bacteria and very small animals, because this video and the abundance of extremely small animals proves that every niche is full.

    That's why evolution is so brilliant.

    Down to bacteria, evolution has created amazingly interesting smaller animals. The earth is 4.5 billion years old and life rose early during that time.

    Evolution is survival, and a slightly larger animal will survive longer.

    So at every level from two cells inside each other and up, there are niches filled with interesting animals.

    What other extremely small, interesting animals are there in this gigantic world?

  13. you know, i really wanted to watch this. but she is by far my least favorite host, for really no fault of her own. i don't like the way she moves or the way she talks, i gave up about 3 minutes in. GIVE ME MORE HANK

  14. 2019 here, and I never realized how animated Olivia used to be. It's really endearing, and I retroactively miss it.

  15. The 2 dirtiest, nastiest and disease infested animals the world could do with out is rats and rats with wings pigeons!!!

  16. I was like, damn, Olivia lost the baby weight really quick! Then noticed the release date. This is back when her vocal delivery wasn't on point but she's an inherently interesting person so it's ok. Maybe it's motherhood, but her voice seems less piercing now, maybe it's just an audio tech adjustment, or some of both. Just watched that accent guy and she could've trained herself to use different resonance chambers.

  17. They meaning depopulation people want you to feel like you mean nothing because the elitist want you to go away these people like to you

  18. Mmmm, I almost believe you . I would bet my left shoe that the most abundant birds/animals are the ones we farm. I'll go read more.

  19. I love scishow but if she doesn't stop? Speaking in questions? Which is really annoying? I may have to mute every video she's in?

  20. The presenter's accent is rather distracting. The other presenters in this channel have a clear, simple accent that's easily understandable even to people whose native tongue isn't English. I had to turn on subtitles for this one.

  21. trillions of ants but quadrillions of these fish? That doesn't sound right, not to mention how does this deep sea fish get energy, there isn't photosynthesis where there isn't light, even if they're scavengers and feed on the dead they can't make up a larger pool of energy than is available to them to eat.

  22. I don't think there are house mouses where I live. That might be because there are a lot of squirrels, rats, and cats. Well, they are all a lot larger than those little mice; so, they can't get into my house as easily. So, if that's what it is, maybe I want those creatures around to keep me from being overrun by tiny mice that can't be kept out.

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