Giant Surfing Crocodiles

The estuarine crocodile is a bad swimmer. So how has it managed to colonize northern Australia, eastern India, part of southeast Asia and multiple South-east Pacific islands separated by enormous swaths of ocean?


It loves to surf. Specifically, it loves to ride ocean tides and currents:

Using acoustic telemetry and satellite positioning or tagged crocodiles, the researchers found that both male and female crocodiles regularly traveled more than 30 miles by 'surfing' river and ocean currents. They always began their voyages within an hour of the river's tides changing, so they could take advantage of the current. When the tide turned against them they pulled up onto the riverbank to wait for the next day's tide.

They also analyzed data showing that one satellite-tagged crocodile traveled 360 miles over 25 days. A second male, went 255 miles in 20 days.

The paper is in this month's edition of the British Ecological Society's Journal of Animal Ecology.

The estuarine crocodile is the world's largest living reptile. Males can weigh up to 2,900 pounds and reach up to 20 feet long. Crocodylus porosus lives mostly in rivers, mangrove swamps and estuaries and cannot survive long-term away from land, where it gets its food and water.

The researchers speculate that the crocodile used their ability to surf the ocean currents to fan out throughout the South-East Pacific. Populations of the giant reptiles are found in East India, Sri Lanka, Southern China, Thailand, the Philippine and Sunda islands (including Sumatra, Java, Borneo, Celebes, and Timor), to northern Australia, Vanuatu, Fiji and the Solomon islands.

There are anecdotal reports of sailors sighting these crocodiles far out to sea, but no one had previously tracked their long-term movements and showed that they used the currents to move themselves quickly between far distant habitats.

The research also helps explain why the various far-flung populations of the crocodiles haven't evolved into separate species, despite the distances between them. They appear to travel frequently enough to maintain a unified genetic profile.

Honestly, that would be one of the craziest things to ever see - you are 200 miles from shore in the Indian Ocean - and chilling in the water is a 20+ ft croc. That would be bizzare.

It could also lead to one of the most epic battles in history - croc vs. shark: