The world’s largest shark is also the world’s largest omnivorous

What did the whale shark do (Rhinekodon Typus) Tell their waiter at the restaurant? “Can I have a side of salad with this?”

This is true! The whale shark dethroned the Kodiak bear (Ursus arctos midendorphi) now to claim the title of ‘largest omnivorous animal’. A slow-moving, filter-feeding animal found in tropical oceans around the world, whale sharks are notorious for appearing each year in Western Australia’s Ningaloo Reef, thanks to annual coral spawning and nutrient uptake. Notables are notorious for taking advantage of the abundant feeding of ecosystems. – Rich water. In particular, they feed on plankton and krill, small marine crustaceans that are high in nutrients.

The fringing Ningaloo Reef is UNESCO World Heritage-listed and one of the largest whale shark aggregation sites in the world, making it a great place for scientists who study these animals to easily find (well easier than). Scientists from the Australian Institute of Marine Science (AIMS), CSIRO and the University of Tasmania recently analyzed biopsy samples from these star-covered visitors and found they are eating a lot – not just plankton and krill, but plant material Too! “It makes us rethink everything we knew about what we knew about what whale sharks eat,” said Dr. Mark Meakon, a fish biologist at the Australian Institute of Marine Science, in a press release. “And, really, what are they doing in the open ocean.”

This is not the first time a shark has been considered omnivorous with the bonnethead shark (sphyrna tiburoLike breaking the internet when it was found that they were eating and digesting sea grass. In fact, this isn’t the first time a whale shark has been found to be omnivorous! Previous research in Japan has shown that whale sharks have blood and tissue chemicals showing that about half of their diet comes from plant material such as algae or sea grass.

But the whale shark tissue of these whale sharks was different from that of Ningaloo. Not only were they eating Sargassum, a type of floating brown algae, but these plants were contributing to their energy and growth. Whale shark tissue was analyzed by CSIRO Oceans and Atmosphere organic biogeochemist Dr. Andy Reville, who used compound-specific stable isotope analysis to study what the animals were using for energy and growth, not what What were they eating? Reville said that while the whale shark swam with its mouth open and swallowed a lot of things, it was interesting to see what was being used specifically by the animal and what was going through the animal’s body: “Because [stable isotopes are] actually involved in the body, [they] are a better reflection of what the animals are actually using to grow.”

Dr Patti Punya, a biological oceanographer at the University of Tasmania’s Institute for Marine and Antarctic Studies, said she was surprised by the whale shark’s biochemical signature. “This is very strange, because in their tissue they do not have the fatty acid or stable isotope signature of a krill-feeding animal,” she said in the press release. However, the researchers also caught and analyzed whale shark poo with a net, which showed they were eating krill but not metabolizing much of it.

“We think that over time in evolution, whale sharks may have developed the ability to digest some of this Sargassum that’s going into their guts,” Meakan said. “So, the sight of whale sharks we have coming to Ningaloo to feast on these little krill is only half the story. They’re actually eating a fair amount of algae as well.” And it makes Meakan wonder about the evolutionary story and how it differs — or doesn’t — between the two different ecosystems: “On land, all the biggest animals have always been herbivores. In the ocean we always think were that animals that have actually grown, such as whales and whale sharks, are feeding animals such as shrimp and small fish one step up the food chain. suggests that perhaps the mechanisms of evolution on land and in water are so different. Not there. ”

The academic paper, available here, is also exciting to another whale shark scientist from around the world: “What I love most about whale sharks is that they challenge much of what we think about sharks.” Alistair Dove, a marine biologist and vice president of science and education for the Atlanta-based Georgia Aquarium, told Mashable. How this will shake things up in the world of whale shark conservation has yet to be determined, but an interesting time comes for these struggling gentle giants.

The biggest threat facing them? We. While the unsustainable fishing pressure – from accidental catches or targeted attempts – is considered a threat to these animals, it is the actual vessels themselves that are also the issue. Whale sharks spend a lot of time on the surface of the ocean as they feed on plankton and other tasty seafood, making them easily vulnerable to commercial fishing vessels. If it is a fatal blow, their body slowly sinks to the bottom of the ocean – neither to be seen nor counted against the dwindling population numbers. In fact, Dove believes commercial shipping can be a silent killer. And there might be one more killer to add to that list!

Assessed as ‘Endangered’ by the International Union for Conservation of Nature (IUCN), little predation is placed on this shark due to its large size. However, that knowledge has been challenged with recent footage of orcas teaming up to take down a juvenile whale shark. Perhaps someone should give orcas the idea of ​​adding a salad to their menu instead of hunting whale sharks – that’s no way to make your vegetable count for the day!

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