Whale sharks are the largest fish on Earth — gentle giants that can grow longer than a bus — yet their feeding habits have remained surprisingly mysterious. A new study published in Marine Biology changed that: researchers attached small cameras to the dorsal fins of five whale sharks at Ningaloo Reef in Western Australia, and the footage they brought back has rewritten what scientists thought they knew.
For decades, whale sharks were assumed to be mostly surface feeders, cruising along with their huge mouths open to scoop up plankton near the top of the water column. The new recordings tell a different story. The sharks spent far more time feeding underwater than expected, using a mix of behaviors from the surface all the way down to the seafloor — including dramatic chases after dense krill swarms at depths of up to 70 meters.
'We discovered whale sharks use a mix of several feeding behaviors throughout the water column and along the seafloor, up to 70 meters deep,' the researchers said. Slow-feeding behaviors were the most frequent, captured across all depths, but the deep dives were a revelation: the biggest fish in the ocean is a capable deep-water hunter, not just a surface skimmer.
The camera tags also captured something of the whale shark's daily rhythm, showing when and where the animals choose to feed. Understanding that is not just academic — it matters for conservation. Whale sharks are listed as endangered, and knowing where they actually eat helps design protected areas and shipping rules that keep these giants safe. The team says the technique opens a new window onto a species that is famously difficult to observe in the wild.
