![]() What’s more, whale shark throats are only about as wide as a grapefruit, which makes it unlikely that anything as big as a shearwater could go down the gullet. Despite having around 300 rows of tiny teeth, whale sharks do not chew. While that’s bad news for baitfish, the birds in Cannon’s footage were not in any danger. Whale shark mouths can reach a whopping five feet across. “They don't seem to be very successful on their own, but when other predators are there attacking the baitfish, forcing them to contract into a defensive ball, the largest mouth gets the most fish.” “By themselves, whale sharks will definitely chase fish around but, bless their spotty hides, they're relatively slow and ungainly,” says marine biologist Simon Pierce, who has been conducting research on whale sharks for more than 15 years, and was not involved with the recent study. Targeting the same bait ball as other predators might further enhance the sharks’ energy gains. It’s possible that for certain individuals, the benefit of high-calorie fish feasts outweighs that of lengthy swims in search of smaller prey. This encounter, and reports of others like it in the region, occurred during the off season–a time when whale sharks typically migrate elsewhere. Whale sharks certainly can manage the feat alone: a group of seven whale sharks were filmed corralling a school of anchovies in the Gulf of Tadjoura, off the coast of Djibouti, in 2017. ![]() What if the same thing is happening here?” Slow and ungainly? ![]() “We know that when bait balls are around, other predators do these spatially-coordinated attacks to maximize their foraging efficiency. “The interactions made my mind race with a whole bunch of questions,” Lester says. Lester and her colleagues wonder if the Ningaloo whale sharks may be leaning on their agile neighbors to do some of the heavy lifting. Feasting beside the dappled giants in Cannon’s footage were other large fish such as tuna, trevally, and whaler sharks, as well as a divebombing cohort of wedge-tailed shearwaters, seabirds in the petrel family. Situated 750 miles north of Perth, the protected UNESCO world heritage site is home to relatively intact predator populations. Ningaloo Reef is renowned for its biodiverse waters. ( Learn more: Whale sharks may live up to a century, Cold War bomb dating reveals.) Both of these tactics require more effort than swimming slowly along, mouth agape, which makes it imperative to land a calorie-dense gulp when foraging this way. The whale sharks in the Ningaloo footage were seen ram feeding–charging at speed through the center of the bait ball-as well as positioning themselves vertically beneath it, primed to hoover fish into their mouths. When you’re longer and heavier than a school bus, eating is all about conserving energy. Each new piece of footage holds unique clues about what drives whale sharks to the bait ball table, and which strategies they use to make the most of it once they get there. ![]() But underwater photographic evidence like this is rare. Eyewitness reports of such events in Western Australia, for example, go back more than 20 years. ![]() Anecdotal evidence of the behavior has been documented at aggregations throughout the world’s tropical oceans. It’s likely that whale shark bait ball feeding occurs more frequently than it’s caught on camera. Even then, notes Lester, happening upon a feeding event like this is akin to finding a needle in an ocean-sized haystack. Whale shark meetups like the one at Ningaloo-which occurs each year between March and August-offer a unique opportunity for scientists and ocean enthusiasts to observe these elusive animals in shallow, nearshore waters. Not only can the behemoths swim across entire oceans, they’re also known to dive thousands of feet beneath the surface. “Whale sharks can be really challenging to study despite their huge size because they’re so mobile,” says Lester. Pinning down the specifics of when, where, and why these animals opt for more sizable sustenance, however, is a difficult task. While krill and other plankton make up the bulk of whale sharks’ diets, scientists have long known that small fish like anchovies and sardines-and even the occasional squid-do appear on the menu. This video captured at Western Australia’s Ningaloo Reef in March 2020 shows a group of whale sharks feeding on bait balls of fish in tandem with other predators, including tuna, whaler sharks, and dive-bombing birds called wedge-tailed shearwaters. ![]()
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