Whale sharks, the gentle giants of the ocean, have long captivated our imagination with their majestic size and graceful movements. But despite their widespread popularity, much of their behavior remains shrouded in mystery, particularly what they do below the surface. Our recent research, published in Marine Biology, uses an innovative approach to finally answer the question: what do whale sharks do when no one is watching?
We attached high-resolution movement tags with small cameras to the dorsal fins of whale sharks at a tropical coastal gathering site in Western Australia. These tags allowed us to capture footage from the sharks' point of view, providing an unprecedented glimpse into their lives below the surface. By reviewing this footage alongside existing scientific literature, we identified 36 distinct behaviors, offering a comprehensive understanding of their foraging strategies throughout the water column.
One of the most surprising findings was that whale sharks exhibit a wide range of feeding behaviors, challenging the previous assumption that they primarily feed at the surface. We observed behaviors such as gliding slow feeding, where they sink to the seafloor with an open mouth, and active surface feeding, where they vigorously swim after krill swarms. However, the majority of their time was spent engaging in six low-effort feeding behaviors, suggesting they often snack in areas with low prey density until they encounter more abundant patches.
This discovery highlights the adaptability of whale sharks in tropical waters, where prey is scarce and patchily distributed. Their diverse foraging strategies may be key to their survival in these challenging environments. Furthermore, our study revealed that whale sharks have a much wider variety of feeding behaviors compared to other filter-feeding megafauna, such as basking sharks and whales.
The implications of our findings are significant for conservation efforts. By understanding the full range of whale shark behaviors, we can better protect these endangered creatures and their habitats. As we continue to unravel the secrets of these magnificent creatures, one thing is clear: whale sharks are the ultimate snackers of the sea, constantly adapting their feeding strategies to thrive in a changing ocean.
