Well hey there, friends. Do you want to hear a story?
Once upon a time, there was a bunny.
And she was a good little bunny and she hopped around her neighborhood every day
finding foods that she liked to eat, and drinking out of rushing streams, and pooping in the bushes.
And at night, she and her family slept in a hole under a big tree.
And every so often, one of her friends, a brother, or somebody, would get gobbled up by a bigger animal, a jaguar or something.
But you know, that was cool because they are bunnies and when you are bunny
you get used to the idea that some day, you're probably gonna get snacked on.
So one day, bunny and a couple of her friends were scurrying around the meadow
when they accidentally hopped right up the ramp
of a spaceship that was heading to Planet Wonderful.
The bunnies didn't know that they'd done that of course, and when the doors closed behind the bunnies
and the spaceship blasted off, they were totally freaked out!
But eventually, the doors opened again and they hopped down the ramp at the loveliest meadow that
they had ever seen!
Planet Wonderful was just perfect for bunny and her friends.
There were fields of four-leafed clover and little vegetable patches
tended by tall, spindly carrot people.
Big dumb cabbages rolled around in the meadows and mooed at the bunnies
when they hopped up to nibble on them.
Bunny an her associates didn't even have to find a tree or a hole to sleep in
because there was nothing on Planet Wonderful that wanted to eat them!
It was so dreamy!
Pretty soon, bunny became romanticly involved with one of her friends and they started having baby bunnies.
Some of the other bunnies had baby bunnies too. And those babies were big and strong and healthy
and just as voracious for cabbages and carrot people as bunny herself had been when she had arrived.
Pretty soon, Planet Wonderful, was covered in bunnies.
In fact, there were so many bunnies that the cabbage cows and carrot people feared them,
and their numbers began to dwindle.
And the bunnies lived happily ever after until they'd eaten every single carrot, cabbage cow, and four-leafed clover on the planet.
What happened after that is a story for well... I'm gonna tell you that in just a minute.
So the end of that story is actually the beginning of this video,
about EXOTIC INVASIVE SPECIES.
They evolved in a special little environment where they had a very specific place or purpose.
And somehow, probably with the help of us humans,
they got to a completely different ecosystem.
In some cases these animals can't handle the new ecosystem and they die,
and in other cases they just... you know... chug along and make life work like everybody else.
But in some cases, like in the case of bunny on Planet Wonderful,
they show up in their new ecosystem and they go all hegemonic on it.
They might become super predators or they might outcompete other species that are living in that ecosystem.
Sometimes they manage to completely alter the habitat of the place that they invade.
Sometimes they hybridize with species that are already living in that environment
diluting their gene pool to the point of extinction.
And sometimes, along with theirselves, they'll bring in a new disease
that will completely wipe out the local population.
But you know, they're really happy to be there because this is now... they've come upon this wonderful, bountiful paradise.
A paradise for them, but for everyone else, a hell.
To illustrate what I'm talking about, I actually have with me today in the studio a couple of
more pernicious but still very adorable examples... uh, you can maybe hear him in the background already,
uh... of invasive species in the United States.
So this little girl is a European Starling. They were introduced to America because there was
a rich guy in New York who just couldn't live with the fact that there were animals mentioned in Shakespeare
that didn't live in America. And so he decided to release 60 starlings into New York City's Central Park...
And now there are two hundred million of them in the United States!
Yeah, you did a pretty good job. You really like it here.
They're very gregarious, they love living in large flocks and they've been outcompeting native birds in America
for... space and for food, and for general peace and quiet since around 1890.
This is the red-tailed boa, which is what you call a "Boa Constrictor" generally.
They're beautiful and sort of lovely to have around if you're a certain type of person
which is why they were brought to America as pets.
And then a few people were like "Maybe I don't want this thing around my 6-month-old infant, it's getting kind of big."
and so, they just let them go into the Everglades and now, they are very happy to be in the Everglades
and have become an invasive species there.
We're gonna kiss. Me and Daisy are gonna kiss.
To illustrate what one of this exotic invasives can do to an ecosystem let's look at Kudzu:
The vine that ate the American southeast. Kudzu was brought to America from Japan,
because it was a cute little ornamental vine with purple flowers and it smelled like laffy taffy.
After a while, because it grew so well, people started having weird ideas about using it to stabilize hillsides
or to feed to livestock.
And Kudzu... appreciated all of the "assistance" it was getting, being distributed across the southeast but...
but let me tell you, it didn't actually need the help.
Maybe it was the soil, maybe is was the hot humid climate... I don't know but whatever it was, Kudzu took it
and made a lot of the southeast look like this.
And you can't blame the plant, it's not Kudzu's fault that it takes over trees and entire landscapes
and cars that happen to be parked in the same place for too long.
Kudzu, like thousands of other plants, were just planted because people thought that it looked good
and it happened to be the one that was trouble.
So Kudzu was kind of a big "Oops" moment in the course of American natural history but,
compared with a lot of other invasive species, Kudzu looks like, you know, a bunch of overgrown bushes
in some old lady's yard. Take the Brown Tree Snake for example, a mildly venomous but a very aggresive snake
that was introduced to Guam during WWII and pretty much collapsed the entire ecosystem of the island.
Before WWII, Guam didn't have any snakes except for the Brahminy Blind Snake which is tiny and blind,
and basically looks and acts like an earthworm. No offense to any Brahminy Blind Snakes
that are watching this but HA! You aren't watching it because you're BLIND.
But during World War II, the Brown Tree Snake hitched a ride in a military cargo ship form the South Pacific
and showed up in Guam. And seriously, Guam was the Brown Tree Snake's Planet Wonderful.
They just started eating... and never stopped. They had no predators, and no competitors, and as a result,
since the snake's arrival, ten of the eleven native bird species in Guam have gone extinct.
Small mammals on the island are also increasingly rare, and since birds were major pollinators of the plants,
the plant ecosystems are also crashing. So it's a complete freaking fiasco and on top of that,
there are now on Guam, thirteen thousand snakes per square mile.
Thirteen thousand, mildly venomous snakes per square mile!
In addition to that being completely like... blegh,
the snakes are also always climbing up power lines and getting electrocuted and causing power outages
and they generally make living on Guam or visiting Guam kind of a terrifying experience.
So here is the question: What do you do when a bunch of snakes, or the equivalent of Audrey II
from The Little Shop of Horrors starts to invade your little island?
Well that is a question that people have been trying to answer for decades without as much success as one might like.
Once something like Kudzu or the Brown Tree Snake is loose, it's pretty much impossible to round them all up
so the first line of defense has to be: Prevent the things from coming in the first place.
These days that doesn't actually work very well because people are very mobile, we like to move around
and when we move around we like to bring our pet Burmese Python with us.
But because now we've seen this happen so many times before all over the globe, it's becoming easier to
spot an alien invasion while it's happening and nip it in the bud before it goes all
Brown Tree Snake Code Red!
A lot of times we actually have to do this the old fashion way: Going in and actually killing every invading animal.
In Florida, where I grew up, they actually encourage people to go hunting for feral pigs.
I don't think they went as far as to put a bounty on their heads, but they did put together
some mighty good cook books for how to make delicious feral pig stews.
But another trick that we've been using is actually bringing in another species from outside
the ecosystem to combat the current invader. This is called Biological Control and as you might imagine,
it has some successes, it also has some pretty tremendous failures. For example,
The lady who swallowed the spider to catch the fly. There are plenty of examples of when Biological Control
has actually worked and nowadays we are actually developing... like a fungus or a disease that will go
after a specific organism and KILL IT!
But probably the best example of Biological Control going awry is when they brought mongoose into Hawaii
to fight the invasive rats. But it turned out that the mongoose actually much preferred
eating the eggs of native birds species to having to go chase down rats.
I don't who didn't see this coming. I mean, when you're given the chocie between eating the raw flesh of a rat
or an egg... I think most species will go for the egg.
But gosh, darn it, if now there aren't a lot more mongoose on Hawaii and a lot fewer native birds.
So I know we are really hating on invasive species right now but there are actually some examples
of where a species invasion has taken an unexpectedly heroic turn.
Take for example the Asian Clam wich showed up in Washington State around the 1930's
brought in by Chinese immigrants who thought that they were super yummy.
So of course, as you might imagine, the clams didn't stay in people's lunch boxes.
Pretty soon they were rivers and streams all over the country, partially because they just don't care much about anything.
They can live pretty much anywhere and if they can't find another clam to breed with, they are hermaphroditic
so they can just fertilize themselves. And on top of that, when contitions are perfect, they can make about 350
babies per day. Talk about business time.
And they live anywhere: lakes, rivers, streams, a glass of orange juice.... they just don't care.
On the other side of the bivalve pickiness spectrum, there are... or at least used to be
tons of native species of American clams. And they actually do care quite a bit about their water quality
and where they live and whether or not they have another mussel nearby to mate with.
For starters, most of them need clean gravel to live on, but the reproductive strategies and habits are
unbelivably fancy and fussy. A lot of them require a specific species of host fish for their larva
to attach to and grow on. And of course there are some species that prefer to have Barry White playing,
and could you please turn down the thermostat a little bit and turn on the humidifier I think that would
help me get into the mood.
And in particular fresh water mussels aren't actually doing that well these days
because mostly of pressures from people. Always with the people.
But like I said before, the Asian fresh water clams are pretty much down for anything.
And that actually turns out to be pretty good because the native fresh water mussels are kind of going extinct.
And that's actually been a good thing for the ecosystems that they've been introduced to because there's
birds and fish and raccoons and crayfish and all these animals that rely on fresh water mussels to be there.
And the picky native ones, they are getting really rare but you don't want the whole ecosystem
to have to collapse because of that. So that's pretty much the exception of the rule.
Invasive species, almost always very bad but also very interesting. And now I'm going to show you a picture
of an exotic Burmese Python messing with a native Florida Alligator. Good night, and good luck.
If you have questions, or suggestions for other things we should cover on SciShow,
you can see us on Twitter and Facebook and of course down below in the Youtube comments,
we will always be there... uh... because we love to see you. Good Bye.