Whale sharks use a wider vary of feeding methods and depths than floor observations beforehand revealed.
A whale shark can vanish beneath the floor in seconds, leaving researchers with little thought of what the world’s largest fish does as soon as it disappears from view. Whale sharks (Rhincodon typus) are among the many ocean’s most recognizable animals, inspiring fascination amongst folks lucky sufficient to come across them and powerful curiosity of their safety.
Most information of whale shark habits has come from snorkeling encounters or observations produced from boats. As a result of these strategies cowl solely the ocean’s floor, a lot of the animals’ underwater lives has remained hidden.
Whale sharks inhabit tropical seas the place prey is usually scarce and erratically distributed, forcing them to regulate frequently as they seek for meals. Local weather change could make these sources even much less dependable, growing the necessity to perceive how the sharks feed.
In analysis printed in Marine Biology, we hooked up cameras to whale sharks gathering at a tropical coastal website and adopted their exercise under the floor.
The footage revealed beforehand unseen behaviors and supplied essentially the most full view but of how whale sharks forage all through the water column, from the floor to the seafloor.
Floor observations captured solely fragments
Earlier than our examine, researchers primarily described whale shark behaviors from watching them in particular person whereas on the floor of the ocean.
This could solely present a snapshot of whale sharks’ full lives, and infrequently these observations ended prematurely when the fish determined to dive deep. For instance, one description of a doable mating try was minimize brief as a result of the whale sharks dove out of sight of our analysis crew.
A typical technique scientists use to research animal habits within the wild is by attaching digital tags. These small trackers present knowledge on actions past the place we will see them. For marine species, that’s both away from the coast but also when diving beyond the surface.
Although info from tags is incredibly valuable to understand movement patterns, we can’t infer specific behaviors from this data – because we still can’t see the animals.
Through our new study, we could finally address the question: “What do whale sharks do when no one is watching?” Filling these research gaps is essential so we can help these majestic, yet endangered filter-feeding animals.
Shark-mounted cameras expose hidden habits
We used tags that accumulate high-resolution motion knowledge and have a small digital camera. The digital camera supplied footage of the entrance half of the shark, together with their very own perspective. It’s as shut as we will get to seeing the ocean by means of their eyes.
With these cameras, we might see what the shark was doing whereas the tag was additionally accumulating knowledge on their motion. We hooked up our tag to the dorsal (prime) fin whereas snorkeling alongside the shark. Unbothered, these mild giants continued to swim whereas we watched them disappear into the open blue water.
After a pre-set 24-hour interval, the clamp and digital camera tag fell off, leaving nothing on the animal and permitting us to retrieve the info with out impacting the whale shark.
Feeding stretches from floor to seafloor
Utilizing our video knowledge alongside a overview of greater than 100 scientific publications describing whale shark habits, we constructed the biggest catalog of whale shark behaviors thus far, defining 36 distinct behaviors.
We found whale sharks use a mixture of a number of feeding behaviors all through the water column and alongside the seafloor, as much as 70 meters deep in our examine website. Researchers beforehand thought whale sharks predominantly feed on the floor, however this discovering challenges that assumption.
The vary of feeding behaviors spanned from successfully sinking to the seafloor with an open mouth (gliding gradual feeding), to vigorously swimming after krill swarms – their most popular prey – on the floor (energetic floor feeding).
The whale sharks in our examine spent most of their time performing six low-effort feeding behaviors. This means they usually snack in water with low prey density till they arrive throughout a patch with larger prey density, equivalent to a krill swarm. Then, their habits modifications to energetic feeding. It’s like snacking from the pantry when you resolve what you’re going to cook dinner for dinner.
We additionally discovered that whale sharks have a a lot wider number of foraging methods in comparison with different filter-feeding megafauna, equivalent to basking sharks and whales. This might assist clarify how they handle to thrive in tropical waters the place prey is proscribed and patchy.
One website leaves bigger questions
Our examine captured behaviors from only one gathering of juvenile whale sharks close to a coast at Ningaloo Reef, Western Australia. If researchers can connect extra cameras to whale sharks at aggregation websites around the globe, we’ll hopefully uncover new insights and proceed to develop our understanding of this iconic species.
Excitingly, we’re starting to grasp the key lives of the largest fish on Earth, and from what we’ve got seen, they’re the last word snackers of the ocean.
Reference: “An ethogram for the whale shark (Rhincodon typus) with insights into foraging plasticity” by Christine Barry, Luciana C. Ferreira, Adrian C. Gleiss, Mark G. Meekan, E. W. Misty Paig-Tran, Robert Harcourt and Michele Thums, 21 July 2026, Marine Biology.
DOI: 10.1007/s00227-026-04900-y
This analysis was funded by Santos Ltd. and the Australian Institute of Marine Science.
Tailored from an article initially printed in The Dialog. 
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