These two things can be true at once, says researcher Yusuke Fukuda.

Fukuda has been fascinated by saltwater crocodiles ever since he saw a documentary about them in high school back in his hometown, Tokyo. It sparked a passion that led him to the Northern Territory of Australia, where Fukuda has monitored saltwater crocodile populations for the past 15 years.

Now, he's at the tail-end of a Ph.D. in ecology and evolution with the Research School of Biology at the Australian National University looking into the movement patterns and genetic diversity of saltwater crocodiles. He explains what it's like to work with the largest and oldest living reptile in the world.

"My job with the Northern Territory Government focuses on two main things. One is population monitoring. The other one is conflict between crocs and people," he says.

Saltwater crocodiles are part and parcel of being in the Northern Territory. But there's a real risk for people near waterways, especially as this once over-hunted species becomes more abundant with protection laws.

Fukuda spends a lot of time boating around the Darwin Harbor, Kakadu National Park, Mary River National Park and the traditionally-owned rivers of Arnhem Land monitoring populations and collecting data on the crocodiles. One method he uses to collect genetic information is to take a tiny tissue biopsy from their tail with a three-meter-long thin pole.