While whale sharks, the world’s largest fish, have the ability to dive hundreds of metres below the ocean surface, it has been discovered that they need to ascend regularly to regulate their body temperature.
It was known that whale sharks typically dive to around 100 metres and return relatively quickly to the surface in what is known as the “yo-yo” dive. This practice is common in air breathing marine animals, but left marine experts curious as to why it was used by fish that do not breath air.
Researchers studied four whale sharks, tagging them with time-depth recorders. It was found the sharks diving the deepest, to 340 metres, would in turn spend the largest amount of time near the surface to warm up after enduring the colder, deeper parts of the sea.