Don’t let the name fool you. Whale sharks are not whales. They are sharks.
And these are the largest species of fish on the planet. They can grow as long as a city bus. In addition, scientists have recently concluded that whale sharks – which have unique polka dots on their bodies similar to fingerprints – are the largest living omnivores on Earth, officially dethroning Alaska’s Kodiak bear. (Whale sharks eat shrimp, plants, and more.)
This large species, unfortunately listed as endangered by the International Union for Conservation of Nature, is mysterious and continues to amaze biologists.
“What I love most about whale sharks is that they challenge everything we think we know about sharks.”
“What I love most about whale sharks is that they challenge everything we think we know about sharks,” said Alistair Dove, marine biologist and vice president of the Aquarium of Georgia, Atlanta-based, at Mashable.
Scientists discover an ancient shark swimming in a truly strange place
One of the most puzzling things about whale sharks is how they give birth. There is a hypothesis As female whale sharks lay their eggs, the eggs hatch inside and eventually release live babies into the water. But so far, researchers have not seen a whale shark mate or give birth. However, fishermen speared, killed, then To cut open a pregnant female shark at a fish market in Taiwan in 1995. Inside were some 300 dead baby whale sharks, which is an unusually high number for a shark.
When Fishermen dissected the animal, realized they had never seen a whale shark with hundreds of offspring, and called local marine scientists, said Jennifer Schmidt, a molecular biologist and director of the Shark Research Institute in New Jersey. The pups were then safely retrieved and frozen.
“We can never follow an animal for its entire life.”
Years later, Schmidt and his team decided to perform a genetic analysis on 10 percent of the puppies to determine their paternity. They found that all the pups had the same father, suggesting whale sharks could mate once, store sperm and eventually fertilize their own eggs.
It is difficult to know what the life of whale sharks is like. This is because they are long-lived animals, likely surviving for well over a century. This makes it difficult to track a single animal and how it migrates throughout its life.
“We can never track an animal for its entire life,” Schmidt said.
(Usually with fish, the number of rings on their bones noted how old are they. But whale sharks don’t have hard bones like other fish, and calculating their age gets tricky, Georgia Aquarium’s Dove told Mashable.)
Whale sharks spend a lot of time on the surface of the water and are easily hit by ships. Scientists say this is one of the reasons for their population decline.
Credit: AvigatorPhotographer/Getty Images
Knowledge of the behavior and migration of whale sharks is crucial for the conservation of this endangered species. Over the past 75 years, we’ve lost about 50% of whale sharks, said Gonzalo Araujo, a whale shark researcher and also a member of the International Union for Conservation of Nature’s Shark Specialist Group.
The main threat to whale sharks is fishing — including incidental or bycatch — despite attempts to protect them in most countries, Dove told Mashable. “People in small villages in developing countries luckily catch a whale shark. It’s enough to feed their village for a while,” he explained.
The next big threat, Dove said, is ships collide with whale sharks. Whale sharks that spend a lot of time on the sea surface eating plankton are easily hit by commercial fishing vessels. Unlike whales, which tend to float after they die, whale sharks often sink after being killed. “Commercial shipping can be a silent killer,” he said.
“Commercial shipping can be a silent killer.”
Climate change could also threaten the decline of the whale shark population. One of their main food sources, plankton, is sensitive to changing ocean conditions like temperature and acidity, and whale sharks will redistribute based on how their prey changes, Araujo told Mashable. . They might not be successful in new ocean regions. “But it’s going to be on longer timescales,” he said.
There is another imminent potential danger to their survival, and that is plastic pollution. Whale sharks are filter feeders, meaning they make their living by ingesting large amounts of water and filtering out small animals. They can’t tell the difference between plankton and small pieces of plastic, Dove said. We don’t yet know what impact ingesting this plastic has on their health, he noted.
Despite years of research on whale sharks, we still know relatively little about their biology and behavior. To better protect these animals, we need to know where they are born, where they breed and where their babies go, Dove stressed. Since tyrannosaurus rex trampled in the Cretaceous millions of years ago, whale sharks did their job in the ocean “I think we have a responsibility to figure out how to live a little better alongside them,” Dove said.