Cracking the mysteries of the elusive, majestic whale shark
Cracking the mysteries of the elusive, majestic whale shark In this 2017 photo provided by Simon Pierce, Jonathan Green checks on a fin-mounted satellite tag on a whale shark in the Galapagos Islands area of Ecuador. ( via AP)
Cracking the mysteries of the elusive, majestic whale shark
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It's the biggest shark and the biggest fish in the sea. It is often found roaming in warm waters around the globe. Typically, it has its huge mouth agape in search of dinner.

Yet despite its hulking appearance, the whale shark has only tiny, almost useless teeth. It is sometimes so docile that entire boatloads of people can swim alongside the enigmatic, spotted beast. It's also one of the least understood animals in the oceans.

A group of scientists spent several weeks diving with whale sharks in the Galapagos Islands last summer and fall. They were attempting to solve some of the most enduring mysteries. They tried some never-before-used techniques on the species in the wild. For instance, they took blood samples and did ultrasound exams, all while swimming furiously beside them underwater.

Here's what's known about these massive marine animals and what scientists are still trying to find out:


While they are comparable in size to whales, whale sharks are sharks. They typically grow to be bigger than a double-decker bus. They grow to 20 to 52 feet and can weigh more than 20 tons. But they are filter feeders - the enormous whale sharks are dangerous only to the plankton, fish eggs and tiny fish they chomp on.

The gentle giants aren't particularly fast when compared to other sharks. But a simple wave of their tail propels them through the water faster than any human could ever swim. They have broad, flat heads and their entire dark-blue bodies are covered in dots that act as camouflage underwater.

They have been overhunted by fishermen for years. Now whale sharks are endangered and at risk of extinction.


Whale sharks prefer warm waters and are often found feeding at locations around the world including Australia, the Philippines, Mexico and even in the oil fields off the coast of Qatar.

Hundreds of whale sharks — mostly young males — congregate in these areas at certain times of the year to scoop up fish eggs. It's unknown where adult females are feeding then.

The vastness of the ocean usually makes the shy animals hard to find — Jacques Cousteau only ever saw two in his decades of sea exploration.


Marine biologists have been tagging whale sharks in recent years to track their movements. Others are trying to answer questions about their life and reproductive cycles. Only one pregnant whale shark has ever been found: In 1995, a dead whale shark was found off the coast of Taiwan with 300 embryos inside, all at different stages of development.

"The million-dollar questions are where are they mating, hunting and where do their young live?" said Jonathan Green, director of the Galapagos Whale Shark Project.

An international database was launched to identify as many whale sharks as possible through their distinctive dot pattern. Each shark has a unique configuration of dots that act like a fingerprint. More than 8,000 sharks have been logged so far. Because scientists can only afford to spend a few weeks in the Galapagos each year, they depend on photos taken by visiting divers to figure out what the whale sharks are up to. So far, none of the sharks spotted in the Galapagos has been seen anywhere else.


Because of the difficulty of conducting a medical exam on a free-swimming whale shark, researchers only obtained two blood samples, which haven't yet been tested. The ultrasound exams were inconclusive and Green said more powerful machines are needed. Most ultrasound machines for animals are intended for abdominal walls that are 1 to 2 inches thick — but a whale shark's abdominal wall is about 8 inches.

"When we first started studying these large animals, nobody knew how to go about it," Green said. "Now that we have better technology and more experience, we will hopefully be able to answer some of the fundamental questions soon."

Besides blood and ultrasound tests, scientists successfully tagged seven sharks. While not a large number, it's important since so few whale sharks are tracked. The pressure of deep water can cause tags to drop off if the sharks dive below 2,000 meters (6,561 feet), which the animals often do if they're traveling long distances or possibly giving birth. But any migratory data the scientists collect when sharks stay at shallower depths can help build a picture of the sharks' life cycle.

Green and colleagues are planning further expeditions to the Galapagos later this year to continue their research, including more blood samples and satellite tagging.

"When you have so few data points, every single shark is important," said Robert Hueter, director of the Center for Shark Research at Mote Marine Laboratory in Florida. He was not part of the Galapagos research. "These aren't like goldfish where you can get sample sizes of hundreds at a time."


In the last 75 years, the vast majority of whale sharks have been hunted by people for food and their numbers are still dropping, said Simon Pierce, chief scientist at the Marine Megafauna Foundation .

Some biologists worry climate change could hurt the sharks by reducing their food supply: rising ocean temperatures could mean less plankton.

"If we do the things that are necessary to conserve the whale sharks, we'll be conserving the ocean itself," said Simon Thorrold of the Woods Hole Oceanographic Institute in Massachusetts.

For Green, who heads the Galapagos project, it's more personal. "Even after years of diving with whale sharks, I still get goose bumps every time I see that huge blue shadow in the water. It's an incredibly emotional experience."

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How can a shark be a whale?
Write your answers in the comments section below

  • WilliamF-del
    3/13/2018 - 08:54 p.m.

    I think the whale sharks are really cool. Whale shark's teeth are almost useless and are so docile that the wouldn't know if a boat full of people were swimming next to it. The whale shark is an endangered species. They are at the peak of extinction.

  • AnnabelleA-del
    3/13/2018 - 09:44 p.m.

    The majestic whale shark is truly an amazing creature. It is known for it's massive size, and it's beautiful blue and white spotted body. This shark has many mysteries that scientists are working hard on figuring out. They include:

    - Reproduction
    - Mating Areas
    - And other possible body processes
    I really am looking forward to finding out more about this majestic creature.

  • RushB-del
    3/14/2018 - 06:18 a.m.

    This article talks about talks about whale sharks and their situation. Whale Sharks are incredibly hard to find and even harder to research, while male whale sharks usually hang around Australia, the Philippines, Mexico, and even the oil fields we still do not know where most female whale sharks hang around, because of the vastness of the ocean even Jacques Cousteau has only ever seen two in his explorations. Testing the whale sharks is also hard, this is because getting blood samples are extremely hard and ultrasound machines don't work

  • NatalieH-del
    3/14/2018 - 03:41 p.m.

    Whale sharks are beautiful creatures. Scientists have been observing them to learn more about them. They live around Qatar, the Phillippines, Mexico, Taiwan, Australia, and more. The only pregnant whale shark was discovered in Taiwan. So far, scientists have tagged over 8,000 whale sharks.

  • JaredI-del
    3/14/2018 - 04:25 p.m.

    Probably a whale and a shark mated

  • GregoryM-del
    3/14/2018 - 05:16 p.m.

    The whale shark is the biggest shark and the biggest fish in the sea.Yet despite its hulking appearance, the whale shark has only tiny, almost useless teeth.

  • PatrickM-dec1
    3/15/2018 - 08:07 a.m.

    The reason why it's called a whale shark is because it is a shark but it's the size of a whale.

  • ChloeR-del
    3/15/2018 - 04:48 p.m.

    This article is about the endangered whale shark, a species that has been hunted for many years.These sharks, the biggest fish in the ocean, are very difficult to observe and live in deep waters near Australia, Mexico, Philippines, Qatar and the Galapagos. Scientists are struggling with this mysterious species and are trying to know more about it because of their life in the deep ocean. With blood test and ultrasound devices, they are trying to track them and know more about them, especially where and how they mate and feed their young. Only one pregnant whale shark was ever found.

  • EsmeraldaV-del
    3/15/2018 - 09:13 p.m.

    This article was about whale sharks. Whale sharks cannot be identified as either sharks nor whales. They're a mix of both. Unlike sharks, they have very small, useless teeth. Their sizes also compare to a whales.

  • RebekahL-dec
    3/19/2018 - 10:20 a.m.

    I had the ability to spend some time with these creatures in Mexico. I think they are majestic and outstanding. It's crazy how they are so peaceful, yet so big. One of my biggest wishes is to go back and swim with another whale shark.

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