People keep finding weird crocs in Florida. Now we know what they are: Nile crocodiles.

Florida is famous for its wildlife.

Bald cypress trees and a great egret in Everglades National Park. Photo from National Park Service/Wikimedia Commons.

Southern Florida is home to the Everglades, manatees, and Florida panthers, not to mention a staggering menagerie of plants, fish, birds, and invertebrates.

But something larger and more dangerous has been lurking in its swamps.

A Nile crocodile in a French zoo. Photo from Alain Jocard/AFP/Getty Images.

Since at least the year 2000, people in southern Florida have been reporting weird-looking alligators and crocodiles. Southern Florida does have both alligators and crocodiles, but these — the ones people were calling about — seemed ... unusual.

Well, for the past few years, some of the people responding to these calls were scientists. They captured three of these animals (at least once right off someone's porch!) and, curious about these strange-looking gators, tested the animals' DNA.

What they found was that these aren't alligators at all. Nor are they the native American crocodile. No, these were Nile crocodiles.

Photo by Tim Muttoo/Wikimedia Commons.

Yes, as in the Nile River. Yes, as in the one in Africa.

DNA reports show that the three animals all shared similar DNA profiles, which suggests they all came from the same source and that all three have ties back to croc populations in South Africa.

There was no evidence that the Nile crocodiles were an established population — that is to say, they didn't find any baby crocs — but where there are three, there's probably more.

"The odds that the few of us who study Florida reptiles have found all of the Nile crocs out there is probably unlikely," study author Kenneth Krysko said in a press release.

Nile crocs are serious business.

A Nile crocodile in a French zoo. Photo from Guillaume Souvant/AFP/Getty Images.

Adult Nile crocodiles can grow to 16-20 feet long and weigh as much as a car. For comparison, the American alligator, which is native to Florida, usually grows just 10-14 feet long.

I never thought I'd have to say that a 14-foot-long reptile predator was small!

So what the heck are these things doing in Florida?! It's probably due to the exotic pet trade.

People sometimes keep big, exotic animals like crocodiles as either pets or attractions. But if the animals escape — or are deliberately released — they can get into the wild and establish a home for themselves.

These crocs aren't the first invasive species to hit Florida. But they may be the biggest.

More than 500 species of non-native fish and wildlife have invaded Florida, including monkeys, giant Burmese pythons, and poisonous lionfish.

Though the lionfish looks pretty, its voracious appetite and lack of predators has made it one of the Caribbean's most wanted. Photo by Alexander Vasenin/Wikimedia Commons.

But Nile crocodiles would be one of the largest and potentially most dangerous. Back in Africa, Nile crocodiles are apex predators, eating just about anything they can catch, from water buffalo to zebras.

This could be bad for native crocs as well, say the scientists. Many alligator and crocodile species can breed with each other, meaning the genetics of our native American crocodiles could start to merge with the Nile crocs.

"My hope as a biologist is that the introduction of Nile crocodiles in Florida opens everyone's eyes to the problem of invasive species that we have here in our state," said Krysko. "Now here's another one, but this time it isn't just a tiny house gecko from Africa."

Luckily, people are working hard to protect our environments from invasive species.

Some programs are designed to help prevent the introduction of invasive species. Exotic pet amnesty programs, for example, give people who can't care for their exotic pets a place to let them go without releasing them into the wild.

Other programs are designed to reduce the impact of invasive species that have already been introduced. For instance, since 2013, the Florida Fish and Wildlife Conservation Commission has sponsored a live-capture hunt for giant snakes called the Python Challenge.

The 2013 Python Challenge in Davie, Florida. Photo by Joe Raedle/Getty Images.

There are even campaigns encouraging people to chow down on invaders in an effort to keep their numbers in check.

Invasive species can be a major problem. But thanks to many people dedicated to monitoring and preventing their release, we can push back against the invaders.

As of now, the Nile croc population hasn't exploded in southern Florida. Hopefully, as more people learn about the dangers of invasive species like this one, we can keep the pressure on the pet trade and other avenues by which these animals arrive and keep them out of places they don't belong.