Saltwater crocodiles migrated thousands of miles to reach the Indian Ocean: What makes them the ultimate wanderers?

Saltwater crocodiles are massive, longer than a bus and heavier than a car - bobbing across vast, shark-filled seas like it’s no big deal.

These huge beasts are some of the most dreaded creatures across the globe due to their eerie appearance. But they are not only capable of making deadly kills; a recent study surprisingly reveals that they are also long-distance swimmers, movers, and settlers.

Saltwater crocodiles were found in Seychelles, but vanished later!

Early explorers spotted crocodiles all along the Seychelles coast 250 years ago. But by 1820 - about 50 years after settlers arrived in 1770 - they were gone. A new genetic study proves they weren’t unique; they were saltwater crocodiles, the species’ westernmost group. Phys.org reports this matches earlier assumptions based on appearance alone.

But how do crocodiles survive in salty oceans and seas?

German and Seychelles researchers combined modern DNA with ancient museum skulls, publishing their findings in Royal Society Open Science.

Saltwater crocodiles thrive in ocean life thanks to salt glands that expel excess salt, allowing them to travel vast distances.

First author Stefanie Agne from the University of Potsdam says, “The genetic patterns suggest that saltwater crocodile populations remained connected over long periods and across great distances, pointing to the high mobility of this species.”

Drifting 3,000+ kilometres

Senior author Frank Glaw from the Bavarian State Collections (SNSB) explains how they arrived: “The founders of the Seychelles population must have drifted at least 3,000 kilometres across the Indian Ocean to reach the remote archipelago, perhaps even much further.” These 6-metre-plus, ton-heavy beasts once spanned coasts from Vanuatu in the Pacific to the Seychelles in the Indian Ocean - over 12,000 kilometres - before their extinction there.

Why crocs thrive at sea

Unlike other crocodiles, saltwater crocs can tolerate seawater for weeks, allowing them to colonise distant islands. Genetic links show ongoing movement across oceans, proving they are the world’s most widespread reptile.

Scientists examined ancient DNA from the lost Seychelles crocodile skulls and confirmed they weren’t a separate species, just distant cousins of today’s saltwater crocodiles. Kathrin Glaw’s photographs show their habitats, such as the mouth of Sri Lanka’s Nilgawa River.

Lessons from lost crocs

Researchers studied three historic Seychelles museum skulls to solve the mystery. Humans wiped out those saltwater crocodiles quickly, but DNA has brought their story back to life.

This wandering ability explains why they’re found across such vast regions. Future research may track modern ocean drifts as the climate changes, highlighting the need for widespread conservation and safe coastal habitats so these roamers can survive.