Whale Shark? Is it a whale? Or is it a shark?
If you already know the answer you’re probably looking for more facts about this awesome creature…
If you don’t, you’re still headed in the right direction!
Let’s get started…
The Rhincodon typus or more commonly known by their other name—the whale shark is the ocean’s largest fish…
They belong to a group of sea dwellers called Chondrichthyes…
This illustrious group includes such creatures as sharks and rays…
At a length of 40 feet, the size of this sea creature is right up there with the largest of extinct dinosaurs…
It’s alive and well, however, can be found swimming in an ocean near you…
See them in action in the video below…
Fish or Mammal?
It’s kinda difficult to view a species of this size as a fish at all, yet it’s a biological fact nonetheless…
They are in the same extended family as your average smallmouth bass, or trout – just a touch bigger in size, that’s all.
Such size pulls focus. Being one of the largest fish in the sea, You’d be forgiven for thinking these unique fish have more in common with whales.
It’s in their name, isn’t it?
Whales are mammals. Whale sharks…are… well… sharks. Despite their name, there’s no relationship between the two at all, although aside from their size they do share some similarities.
Let’s take a deeper look at the world’s largest fish…
There’s more to them than meets the eye. And that’s saying something – after all, there’s A LOT of fish to meet the eye!
Whale Shark Teeth
Whale sharks have approximately 3000 teeth. Clearly, there’s no animal more frightened of the dentist than them.
Its teeth are less than a quarter-inch long and laid out in 300 rows. Interestingly, its shark cousins only manage up to 30 rows.
More Teeth Than Usual
It’s a mind-blowing number, especially considering they don’t really use them to eat. They primarily use filters to feed. More on that later…
Its legions of teeth sit inside a mouth that can be up to 5 feet wide…
This huge orifice also contains 20 filter pads – an important tool it uses for feeding on small prey.
Unlike its shark cousins, it’s giant mouth sits on the front of its head. Other sharks, such as the hammerhead or great white have their mouths situated on the underside of their heads.
Whale Shark Skin
Whale sharks have thick skin…
Insults are no problem for this large fish. The dark gray skin on its back can be over 5 inches thick providing excellent protection from any would-be predators.
If that wasn’t enough, they can also clench the muscles immediately beneath their skin, turning its back into an impenetrable fortress.
Conversely, the skin on its underbelly is relatively soft and therefore vulnerable…
Even though they permit divers to approach them, they have been known to turn their vulnerable underbelly away from divers as they approach.
What is the color of Whale Sharks?
Their skin is dark gray with a white underbelly and has white spots on their body.
Interestingly, the patterns of pale-colored or white spots and stripes on the body of whale sharks are unique to each member of its species…
Like how unique stripes are to zebras, patches are to giraffes, and fingerprints to humans.
Like it’s shark cousins and the common mola fish, a whale shark’s skin is made up of very small tooth-like structures called dermal denticles. This gives its skin a very rough abrasive texture.
Later we’ll reveal how astrophysicists from NASA have helped biologists track individual whale sharks using their unique skin patterns.
So stay tuned…
Whale Shark Length and Weight
There’s a lot of speculation when it comes to length and weight, verification is extremely difficult…
You can’t just pick up a whale shark and put it on the scales. Asking them has proven pretty ineffective too.
So how do they know without proper data?
In the absence of verifiable data, scientists will use estimates. Historical data remains controversial because claims cannot be verified, and there are some pretty amazing claims made about their size.
Average Weight of a Whale Shark
The average weight and length of whale sharks are estimated at 20,000 pounds and 32 feet. Already huge numbers.
Unverified claims include a whale shark caught off Taiwan in 1994 that weighed in at 79,000 pounds. There are others claiming lengths of 75 feet and a weight of 220,000 pounds. Astonishing yes, but unverifiable.
In terms of the largest verifiable length, an ‘accepted’ observation was made in the Arabian Sea in 2001, with a whale shark measuring in at 62 feet.
Considering their incredible popularity today, it’s surprising that there had been less than 350 confirmed reports of whale sharks worldwide before 1980.
To make matters worse…
In 2016 the International Union for Conservation of Nature (IUCN) elevated whale shark status from vulnerable to endangered in its red list.
Despite our apparent love for the species, current trends may see these species become critically endangered.
While science and conservation organizations do their best to protect the species, it’s an unfortunate possibility that their future may be significantly shorter than their past.
A Topwater Dweller that Visits the Deep
Whale sharks prefer surface sea water temperatures from 70 to 80 degrees Fahrenheit, which is why they usually inhabit coastal waters.
They spend 50% of their time in the top 100 feet below the surface…
Tagged fish have been recorded spending over 10 hours at a time swimming at depths of up to half a mile…
Scientists suspect temperature regulation and feeding as the likely reasons for this behaviour.
While warmth and tropical regions is certainly their thing, they have been known to dive as deep as 6000 feet into the water…
That’s over a mile below the surface where the water temperature is far cooler than that of their usual tropical haunt.
Whale sharks are highly migratory animals, moving frequently within their boundary latitudes…
The migration habits of these species remain poorly understood, yet latest tagging and tracking programs are set to develop our understanding.
The use of technologies such as satellite tracking delivers invaluable information.
However, the collection and necessary interpretation of data is a lengthy process…
Information from current tracking has revealed that whale sharks will travel up to 8000 miles. Whale sharks swim slow, their journey can take 3 years or more with their slow swim speed of 3-5 miles per hour.
Gathering to Feed
Biologists assume with some level of certainty that migration relates in part to feeding. Usually, whale sharks like to roam the oceans around the world alone. It is uncommon to see many whale sharks in a single area…
But they have been recorded congregating around the coast off Western Australia, Indonesia, and Belize for annual migratory feasts.
It’s the sea off the Yucatan Peninsula and the Galapagos Islands that draw large crowds…
As many as 800 whale sharks are attracted to these sites every season for their annual plankton chow down.
Individuals frequently return to these sites to feast on plankton. Some regulars have returned to these sites six years in a row.
It would seem that even fish have their favorite restaurants.
DID YOU KNOW?
In 2011, one of the largest gatherings of whale sharks was recorded, more than 400 whale sharks gathered off the Yucatan Coast.
NASA’s Contribution to Whale Shark Science
With the help of astrophysicists, biologists have adapted an algorithm that NASA scientists use to map star fields in the infinite depths of space, to track whale sharks with the markings on their back.
The NASA algorithm was tweaked a little to map the unique markings on individual whale sharks to help with identification.
Individual whale sharks are identified with the algorithm, then entered into a database…
Anybody who sees a whale shark, can take photos and send the photos plus details to ECOCEAN to help with whale shark identification.
The details are entered into the database, registered or hopefully matched to existing data…
This is a great way to involve the general and ocean-faring public in helping scientists and the world learn more about them.
Let’s dig a little deeper…
These observations have led biologists to pose a likely breeding scenario…
It is thought that females may take a very long journey to the middle of the ocean, populating the remote coastal waters near structures such as small islands or submerged mountains, to give birth.
You might be wondering why they travel too far…
It is thought that giving birth at remote waters may provide young whale sharks more protection whilst they’re at their most vulnerable.
Scientists are hopeful that further tracking will help shed more light on the current educated guess.
Life spans of Whale Sharks
It’s estimated that whale sharks live from 70 to 100 years making them one of the longest living cartilaginous fish in the world.
Some speculate they live as long as 150 years but no one really knows how long this species lives…
Females reach sexual maturity at 30 years of age, or roughly 26 feet in length. A female can produce up to 300 pups that are fertilized internally via sperm from the male claspers.
The eggs are held in her uteri (she has 2) until hatching, passing live young into the water of a size of 16 to 24 inches long.
Whale sharks are viviparous, they do not lay eggs.
The eggs remain in their mother’s body. Their offspring are born in the mother’s body out of egg capsules.
There is evidence to suggest that the female does not give birth to all her young at once.
Instead of developing all of its fertilized eggs, it is suggested that she will hold the sperm from her last mating over an extended period, fertilizing eggs to give birth periodically.
DID YOU KNOW?
Whale sharks have never been observed giving birth, however, mating has been observed twice.
A third ‘attempted’ mating was filmed from an airplane off Australia. The mating was not successful, however, as the female was apparently immature.
There’s little if any growth rate data of whale sharks in the wild. However, observations of captive whale sharks prove their rapid growth.
One young whale shark grew at a rate of 18 inches per year, for a touch over two years. A newborn in Japan took just over three years from 1.7 pounds to reach 333.4 pounds.
That’s incredible growth in anybody’s language. It is broadly accepted, however, that such rapid growth rates will not be sustained to maturity. As the shark matures, growth will slow.
Unlocking the Mysteries
Scientists believe that current tagging and tracking will reveal more about whale shark biology…
However, as they live half their lives out of sight, observing them in the wild remains difficult.
For six months of the year, whale sharks are hard to find…
Further to this, breeding grounds remain a mystery and juveniles are rarely observed.
This presents significant challenges for science that is on a determined mission to plug the knowledge gap.
Whale sharks may feed by either swimming along the sea with their wide mouths open, collecting plankton, or by actively sucking in huge volumes of water, including plankton or every unfortunate creature swimming in its way. Much like a huge oceanic vacuum cleaner.
Not quite what you expected isn’t it?
It’s surprising that such a large animal feeds on planktons and other creatures that are often far smaller than a match head.
DID YOU KNOW?
A juvenile whale shark is estimated to eat as much as 21 kg (46 pounds) of plankton per day.
As we mentioned earlier, its thousands of teeth in its wide mouth are not really used for feeding. They swallow their food whole when they eat – so no need to chew, rip, and tear.
Whale sharks feed using filter pads and gill slits behind their eyes. These unique gill rake-like structures act like a net or sieve.
Attached to their gills, filter pads catch plankton and other small organisms while allowing the huge volumes of water to pass through their gill slits when they are feeding.
They could filter prey as small as 1 millimeter through their gills when they feed.
Cheeky Thieves Inviting Trouble
Whale sharks have been known to suck fish directly from commercial fishing nets. Not quite a drive-thru, and not really a buffet, but it’s certainly an easy way to feed.
Check out this cool video of a whale shark sucking fish from a fishing net…
Scientists deem this behavior as highly irregular. That stands to reason, as it’s certainly not natural…
This phenomenon rarely happens and is usually a result of fishermen leaving their catch in the net as good catch has filled all space on board.
Biologists expect that the greedier sharks when near those tempting fishing nets will get themselves in trouble. The chance of net entanglement is very high and likely to prove fatal.
Sharks eating Sharks
Bones taken from the stomachs of sharks have demonstrated that juvenile whale sharks do indeed fall victim to sharks on occasion.
In a recent investigation of a great white caught 50 years ago, scientists found the vertebrae of a whale shark that would have been around 27 feet long.
This demonstrates that there may be a possibility that great whites at least, might prey not only on juvenile whale sharks but also on mature whale sharks.
But that’s not the main problem….
Humans a Danger for Whale Sharks
The biggest killer of whale sharks is boats and people. So, just people – boats are not exactly independent.
Loss of natural habitat, which in turn causes loss of food sources, is also a human-driven threat for whale sharks.
They are also targeted in parts of Asia for their fins and meat…
This puts a lot of stress on the whale shark population, particularly around parts of Asia that are important feeding grounds.
Too Much Love? Or Exploitation?
Whale shark tourism, once a tiny cottage industry, is now huge. It’s certainly possible for a society to love something too much and possibly to the whale shark’s detriment.
For example, whale shark tourism in Mexico has grown from just a few hundred tourists to as high as 12,000 tourists per year.
Mexico is one of the few countries that has whale shark tourism laws.
Whale Shark Tourism
The World Wildlife Federation has written an article about responsible whale shark tourism…
They’re very concerned this growth in tourism will put terrible stress on the whale shark population.
This circumstance is understandable and should have been predicted. Whale sharks are docile, gentle giants, and of no threat to humans.
Of course, people will want to swim and dive with them…
It’s a gentle creature that allows divers to get close and swim with them, whale sharks will even allow divers to hitch a ride on their fins.
Is such a practice sustainable? Should it be encouraged? Or should we just allow them to swim about their business in the wild undisturbed?
Whale sharks in Captivity
There are several aquariums around the world that hold whale sharks.
While aquariums argue that public awareness is critical to whale shark conservation, that notion is hotly contested…
Arguably the best of the aquariums housing whale sharks is the Georgia Aquarium. Holding 6.3 million gallons of water, there is enough space for 4 whale sharks. This aquarium even has a live web-cam.
Arguably the worst example of a whale shark aquarium is the Yantai aquarium in China. They have (had) 5 whale sharks with the largest 50 feet long, enclosed in a small area measuring only 88 feet by 52 feet.
This seems an impossibly small space for such a large animal to live in…
It brings into question the validity of keeping megafauna in such places. Especially when their prognosis outside the ocean is so drastically poor.
They’ll not be satisfied with anything less than an intimate encounter, close up and personal with the largest fish in the world.
It’s a good thing that…
These majestic creatures don’t seem to mind at all, and are known to happily allow us to hitch a ride on its ample fins; as long as we let it pilfer the odd fishing net from time to time.
Science wants to study it; divers want to ride it – swim with it, and some of us prefer to eat it.
Until we all respect its personal space, stop messing up its home and take it off our menus, this gentle giant may find itself in an upstream battle to live peacefully into the future.
It’s our responsibility to ensure we tread carefully with our whale shark interaction. If we’re sure not to take too much, you could guarantee that the whale shark will give us plenty.
If you enjoyed the article, feel free to share the awesome content! Help spread awareness by making others discover how awesome these gentle giants are!
1. Whale Shark Size Scale Compared to Humans By Matt Martyniuk – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9645477