- [Voiceover] I know monsters aren't real,
but there's an invasive fish here in the U.S.
that breathes out of the water and walks across land.
What the hell is going on?
I called Pam Fuller and Matt Nelson.
- [Lady On Phone] Hello, we're here.
- [Voiceover] Both fish biologists,
who study non-indigenous aquatic species
'cause I want to talk to them about
this straight up, badass fish.
- [Lady On Phone] The proper name for it
is actually Northern Snake head.
- [Voiceover] Thanks, Pam.
When the Northern Snake head was found
on the eastern U.S. coast in 2002,
the media went crazy, because this fish was named
one of the most invasive species to date.
Its origins are in Asia, but scientists
aren't sure how it got here.
Some say it may have escaped a fish market,
like, walked off and made it into a nearby stream
where it found a new and suitable home.
And this wouldn't have been hard.
Here's why.
If you were to make a successful invasive species
checklist, this fish checks every single box.
- [Lady On Phone] Lots of progeny, parental care,
broad thermal tolerance.
- [Voiceover] Meaning they make lots of babies that survive,
can live almost anywhere, and eat almost anything.
- [Man On Phone] Whatever they can
fit in their mouth, they're gonna eat.
- [Voiceover] And they can breathe out of the water.
How is this even possible?
Matt told me Northern Snake heads are called
obligate air breathers, which means
they must breathe on the surface periodically
in order to survive.
- [Man On Phone] They have a chamber kind of
in the back of their mouth, kind of behind where
the gills are, you can think of it
kind of like a very rudimentary lung,
and that allows the fish to extract oxygen out of the air.
- [Voiceover] And because they can breathe air,
they can crawl out of whatever body of water they're in
and into another, where say, there might be more food.
Even if that trek takes them a few days.
The Northern Snake head has a firm hold in our rivers'
ecosystems, much to the dismay of ecologists.
And while fishing has helped control its populations,
these guys are here to stay.