Scientists have discovered the world’s largest shark that is not actually a carnivore – ScienceAlert

The largest shark in our oceans is famous for being a gentle giant, and there seems to be more to it than we ever realized. whales and sharks (Rincodon type) are filter feeders, believed to carefully comb the water for small animals such as krill.

Among the young swimmers they catch are greens, which are made up of algae and other organisms that carry out photosynthesis.

This can’t be avoided, but the researchers wondered if these plants were merely garnishes for carnivores, or if they provided a necessary side salad to keep them swimming.

Researchers examining stool and skin samples have determined what ocean bugs 10 meters (32 feet) in length benefit from the giant pools of water they seep through their systems.

The stool showed they were eating krill. Says University of Tasmania biologist Patty Virtu. “But they don’t metabolize much of it.”

Instead, it appears that whale sharks, which are true sharks with cartilage instead of bone, extract nutrients from a heck of a lot of algae.

“It makes us rethink everything we thought we knew about what whale sharks eat,” Says Fish biologist at the Australian Institute of Oceanography Mark McCann. “And in fact, what they do in the open ocean.”

Tissue analysis by Mikan and colleagues also revealed a fatty acid profile that was more consistent with meat than with meat. They found skin rich in arachidonic acid (ARA), which is present in amounts large enough to explain the levels found in whale sharks, in floating algae. Sargassum.

in 2019, Another study Using tissue samples, he also found evidence that whale sharks actually feed on at least some organisms lower in the food chain, such as plants and algae. What’s more, they aren’t the only carnivorous sharks: Bonnethead sharks (Sphyrna tiburo) Eat a lot of seaweed.

These animals are also called shovel heads For obvious reasonsPlant material is often ingested by hunting small prey such as crabs, mollusks and fish in dense seagrass habitats. So their need to deal with this plant matter passing through their bodies is probably what happened to their ability to digest it.

The researchers suspect that the same may have happened to whale sharks. In their evolutionary past, they may have originally pressured algae to digest the animals living on them (epibionts), but they can now also digest and benefit from the same algae.

“So the vision we have of whale sharks coming to Ningaloo to feed on these little krill is only half the story,” he said. explain mikan. “They actually eat a fair amount of algae, too.”

Unfortunately, to find enough of this floating organic matter, whale sharks must follow oceanic features such as surface currents that hold floating food sources together. These same features also collect pollutants in the ocean like plastic – so whale sharks end up accidentally feeding on those pollutants as well.

Mikan notes that some of this plastic passes through a whale shark’s poop. But it could potentially reduce their gut capacity, slow their digestion, or cause their food to miscarry, the team notes in their paper. this is can be harmful these Endangered animals who have experienced a 62 percent population decline in the past 75 years.

“On Earth, all the largest animals have always been herbivores,” Says mikan. “At sea, we’ve always thought that animals that got really big, like whales and whale sharks, were feeding one step in the food chain on shrimp-like animals and small fish.

“It turns out that perhaps the system of evolution on land and in water is no different after all.”

This research was published in Ecology.

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