The World’s Largest Shark is also the World’s Largest Giant Shark

What did the whale sharks doTypus rhinoceros) say to their waiter in the restaurant? “Can I have a side of salad with that please?”

It’s true! Kodiak bears have been destroyed by the whale shark (Ursus arctos middendorffi) now claim the title as ‘the largest omnivorous animal’. A slow-moving, filter-feeding animal found in tropical oceans around the world, whale sharks are famous for showing up at Ningaloo Reef in Western Australia every year to take advantage of the great abundance of food ecosystems thanks to annual coral spawning and nutrient upwelling. -rich waters. Specifically, they feed on plankton and krill, tiny oceanic crustaceans that are highly nutritious.

The Ningaloo Reef is on the edge of the UNESCO World Heritage list and is one of the largest aggregation spots of whale sharks in the world, making it an ideal place for scientists studying these animals to easily find them (well, easier). Scientists from the Australian Institute of Marine Science (AIMS), CSIRO and the University of Tasmania, recently analyzed biopsy samples from these star-clad visitors and found that they eat a lot – not just plankton and krill, but matter plants too! “This forces us to rethink everything we thought we knew about what whale sharks eat,” Australian Institute of Marine Science fish biologist Dr Mark Meekan said in a press release. “And, really, what are they doing out in the open ocean.”

This is not the first time that a shark has been observed to be omnivorous, with bonnethead sharks (Sphyrna tiburo) kind of broke the internet when they were found to be eating and digesting sea grass. In fact, this isn’t the first time whale sharks have been found to be omnivorous, either! Previous research in Japan showed that whale sharks had blood and tissue chemistry that indicated that about half of their diet came from plant materials, such as algae or sea grass.

But this whale shark tissue from Ningaloo was different. Not only were they found to be eating sargassum, a type of floating brown algae, but these plants were increasing their energy and growth. Whale shark tissue was analyzed by Dr Andy Revill, CSIRO Oceans and Atmosphere organic biogeochemist, who used specific stable isotope analysis to study what the animals were using for energy and growth, not just how much they were eating it. Revill said that while the whale shark was swimming with its mouth open and ingesting many things, it was interesting to see what specifically the animal was using and what was just going through the animal’s body: “Because of [stable isotopes are] actually incorporated into the body, [they] they are a much better representation of what the animals are using to grow.”

Biological oceanographer Dr Patti Virtue, from the University of Tasmania’s Institute of Marine and Antarctic Studies, said she was surprised by the whale shark’s biochemical signature. “It’s very strange, because an animal that eats krill does not have a fatty acid or stable isotope signature in their tissues,” she said in the press release. However, the researchers also captured and analyzed whale shark poo, showing that they were eating krill but not metabolizing much of it.

“We think that over evolutionary time, whale sharks have evolved the ability to digest some of this Sargassum that’s going into their minds,” Meekan said. “So our vision of whale sharks coming to Ningaloo just to feast on these tiny krill is only half the story. They’re out there eating a lot of algae too.” And it makes Meekan wonder about the story of evolution and the difference between it and the difference between two different ecosystems: “On land, the biggest animals have always been herbivores. In the sea we always thought that the animals that got really big, like whales and whale sharks, were feeding one step up the food chain on animals like shrimps and small fish. It seems that the evolutionary system on land and in water may not be so different after all.”

The academic paper, available here, is also inspiring to other whale shark scientists around the world: “What I love most about whale sharks is that they challenge everything we think we know about sharks,” Alistair Dove, 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 remains to be seen but it comes at an interesting time for these struggling gentle giants.

The biggest danger they face? Us While unsustainable fishing pressure – from bycatch or targeted efforts – is known to be a threat to these animals, so are the ships themselves. As whale sharks spend a lot of time at the surface of the ocean eating plankton and other tasty seafood, they are easily hit by commercial fishing vessels. If it’s a fatal blow, their bodies simply sink to the bottom of the ocean – never seen or counted against the dwindling population. In fact, Dove believes that commercial shipping can be a silent killer. And maybe there’s another killer to add to that list too!

Considered an ‘Endangered’ shark by the International Union for the Conservation of Nature (IUCN), this shark is a little scary because of its size. However, that knowledge was challenged when recent footage of orcas teaming up to take down a young whale shark. Maybe someone should consider adding orcas salad to their menu instead of munching on whale sharks – that’s not counting your vegetables for the day!

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