What is a whale shark? Is it a whale AND a shark? That sounds like a terrifying combination!
Well, what if we told you that this animal is also the biggest fish swimming in the ocean today?
It sounds like a scary proposition, doesn’t it?
Luckily you needn’t worry, as we’re here to sort out the facts from the fiction regarding these colossal sea creatures.
Amongst many other interesting facts, we’ll learn that the whale shark is an entirely peaceful animal that can grow as long as 18.8 m (61.7 ft) by eating only tiny ocean plankton and the smallest of fishes!
The fascinating whale shark lives a relatively unknown life, but we’re going to tell you all that we know about this incredible giant of the ocean.
What Do Whale Sharks Look Like?
From everything you’ve already heard, you might imagine that the obvious answer to “what do whale sharks look like?” is BIG!
While size may be their standout feature, baby whale sharks have to grow up to make massive adults, and as the youngsters look just like the giants but in miniature, let’s find out what they all look like, irrespective of size.
Whale Shark Appearance
Whale sharks have the general shape of a typical large shark overall, albeit with some notable differences.
Their head is especially wide and flattened from the back to the front.
They have broad mouths that are right at the front of their head rather than being slung beneath as they are in most other sharks.
The mouth stretches for the entire width and is impressively large when the shark is feeding.
The whale sharks’ eyes are small for their size and sit just behind the front corners of their head.
Round spiracles are situated just back from the eyes, and the shark has five pairs of large gills behind them.
Whale sharks have three prominent horizontal ridges that look like ribs on their sides that can be seen on the upper flanks from behind the gills to the fish’s caudal peduncle, where the body meets the tail.
Whale sharks have two dorsal fins, long pectoral fins, paired pelvic fins, and one anal fin. The shark’s tail is heterocercal – taller on top than below and moves powerfully through the water from left to right as the giant swims.
In large adults, the first dorsal and tail can reach over 1.5 m (5 ft) in height.
The whale shark’s coloration also stands out. They tend to be dark blue-gray, gray-brown, dark gray, or black on their top and sides with a light or white-colored belly.
The dark areas of the shark are covered with numerous light spots and stripes, making up a unique fingerprint that marine biologists can use to identify individuals.
As filter feeders, whale sharks are often seen with numerous remora fish hitching a ride and scavenging for scraps.
How Big Is a Whale Shark?
When born, whale sharks measure between 40 to 60 cm (16 to 24 in) long.
However, the maximum size of this shark is truly impressive.
The largest whale shark ever measured was an incredible 18.8 m (61.7 ft), making this the longest non-cetacean creature (whale) on earth and by some margin the biggest shark.
Female specimens appear to grow larger than the males, and studies have suggested that average males get to about 8 to 9 m (26 to 30 ft) while typical females reach 14.5 m (48 ft).
Although the evidence isn’t clear, some scientists believe that exceptional female whale sharks may be able to reach up to 21 m (68.9 ft).
The weight of a whale shark is hard to estimate as they cannot be removed safely from the water.
However, it’s reasonable to estimate that typically sized adults could weigh more than 15,000 kg (33,070 lbs).
Whale Shark Taxonomy
The scientific name for a whale shark is Rhincodon typus.
We can give the full description as follows:
Kingdom – Animalia
Phylum – Chordata
Class – Chondrichthyes (Cartilaginous Fish)
Subclass – Elasmobranchii (Sharks, Rays, Skates, and Sawfish)
Order – Orectolobiformes (Carpet Sharks)
Family – Rhincodontidae
Genus – Rhincodon
The modern species is the only remaining member of the Rhincodontidae whale shark family, with related species, including the even larger Palaeorhincodon from the Paleocene and Eocene eras, being long extinct.
Is a Whale Shark a Shark?
Yes, a whale shark is a shark!
It’s believed that the name came from the shark’s massive whale-like size. It may also have originated from the species’ feeding behavior which is similar to that of baleen whales.
However, whale sharks are Chondrichthyes with a cartilaginous skeleton, rather than whales which are marine mammals with bony skeletons.
Whale Shark Characteristics
Considering their substantial size and external appearance, the whale shark has several other standout characteristics that are also worth knowing.
Whale Shark Teeth
We’ll look at what whale sharks eat in detail below. For now, you just need to know that they’re filter feeders that take in huge mouthfuls of seawater and use their modified gill raker filter pads to capture plankton and small fish to digest.
Knowing this, it might surprise you to hear that whale sharks have any teeth at all. But in fact, they probably have the most teeth of any shark.
As the giant, filter-feeding shark has evolved, it lost any obvious use for teeth. However, whale sharks continue to have around 3,000 vestigial teeth in each jaw set out in 300 rows.
These hooked cusp teeth are less than 6 mm (0.2 in) tall and covered in a skin membrane.
They appear to play no role in feeding or, indeed, have any other function and seem to be waiting for evolution to eliminate them all together.
Whale shark eyes poke out of the sides of their heads and could be vulnerable to damage as they lack eyelids. Luckily, the shark has developed some neat methods of protection.
First, they can draw the eye back into its socket to a depth of about half its diameter when feeling threatened.
They also have dermal denticles on the eye’s surface that are described as being like tiny teeth and act as a protective armor layer.
Scientists have observed as many as 3,000 denticles around the iris on one whale shark eye.
It’s believed that this protection significantly contributes to the whale shark’s long and successful life by maintaining one of its most valuable senses.
Scientists researching whale sharks have discovered that they are exceptionally proficient at healing wounds to their fins and skin.
Minor fin injuries have been observed to regenerate to leave the shark almost as good as new. Additionally, the shark’s distinctive spot and stripe markings return to the repaired area leaving the animal’s “fingerprint” intact.
Whale Shark Life Cycle
Whale shark lifespan is estimated at between about 80 and 130 years.
Scientists do not know a great deal about these incredible creatures, and age estimates have been made by counting growth bands in the vertebrae of deceased specimens.
Whale shark mating hasn’t been properly observed, but it appears to occur with belly-to-belly contact near the surface. Whale shark maturity is believed to be reached at about 25 years of age.
Whale shark birth has never been witnessed, and scientists can only take educated guesses about where it occurs in the oceans.
However, pregnant females caught by fishing boats have shown that the whale shark is ovoviviparous and gives birth to live young after the eggs have hatched inside the womb.
A fishing boat caught a female shark measuring 10.6 m (35 ft) in 1996 carrying around 300 embryos, so it’s believed that one shark gives birth to a considerable number of pups.
However, it is thought that females store the male sperm and use it to fertilize their eggs over a period to give birth to a stream of pups over an extended timeframe.
Baby whale sharks have been observed in the Philippines, St Helena, India, and the Maldives, meaning that these areas may contain birthing grounds.
However, at present, the exact locations and depths remain a mystery.
Where Do Whale Sharks Live?
Whale sharks live in tropical and warm-temperate seas and can be found in coastal waters of varying depths, inside coral atolls, and around reefs.
Reasonably frequent whale shark sightings take place in many countries, including:
Australia, India, the Arabian Gulf, the Maldives, Taiwan, Seychelles, Honduras, South Africa, Kenya, Belize, Mexico, the Galapagos Islands, Chile, Thailand, the Philippines, Malaysia, Mauritius, and Indonesia.
Whale Shark Behavior
Whale sharks are often seen as solitary animals. However, they can appear in large aggregations into the hundreds where significant amounts of food are available.
For example, during mass coral spawnings, or where there are vast schools of small fishes, numerous whale sharks may congregate to take advantage of a large and nutritious meal.
Whale sharks have been observed to be migratory species, primarily traveling long distances to follow their food or perhaps to breed.
As filter feeders, they are often observed relatively close to the water’s surface during the day.
However, studies have shown tagged whale sharks making extremely deep dives, including the deepest ever recorded for a fish of 1,928 meters (6,325 ft).
Can a Whale Shark Hurt a Human?
Given its vast size, it’s natural to wonder if a whale shark could bite or hurt someone.
In truth, whale sharks are not aggressive in any way and are often curious about scuba divers or swimmers they come across.
While the filter-feeding whale shark’s mouth presents no danger to people, getting too close to the giant fish might.
Conservation organizations advise keeping a respectful distance from a whale shark, as much for a diver or snorkeler’s safety as the sharks. An accidental blow from the colossal tail could cause a lot of damage!
What Do Whale Sharks Eat?
Whale sharks are filter feeders and eat plankton and small fish.
They feed either by swimming through the water with their mouths open – ram filtration, or by actively opening and closing their mouth as they stay in one spot – suction feeding.
Whichever method they use, the whale shark pushes the food containing seawater across its filter pads. Food is separated by cross-flow filtration, and the water is pushed out through the gills.
The remaining food particles travel down the shark’s throat to be digested.
Unfortunately, this reasonably indiscriminate feeding method means that whale sharks are susceptible to ingesting foreign materials.
Fortunately, they can clear larger pieces from the filter pads with a kind of coughing maneuver.
However, whale sharks have been found with considerable internal build-ups of microplastics from human pollution of the seas.
What Hunts Whale Sharks?
Whale sharks may not fit the typical image of an apex predator as a great white shark does.
However, they don’t appear to have natural predators that feed on healthy adult individuals.
Opportunistic predators may take young or sick whale sharks, including killer whales, great white, tiger, or bull sharks.
Unfortunately, the greatest enemy of the whale shark is humans, who catch them for their fins, flesh, cartilage, jaws, skin, and liver oil.
Whale sharks are also frequently injured or killed as by-catch by commercial fishing boats or accidentally as they swim near the surface by boat traffic.
Are Whale Sharks Endangered?
The International Union for Conservation of Nature considers the whale shark to be endangered globally, with studies suggesting that the remaining population is decreasing.
Extensive studies are needed to preserve these incredible animals, along with controls of fisheries, by-catch, and vessel strikes.
Many countries, including the Philippines, India, and Taiwan, have banned whale shark fishing entirely. Unfortunately, these bans are often ignored due to a lack of effective policing.
Whale sharks are listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning that their global trade is supposed to be carefully monitored and limited.
It really is incredible to think that the largest fish in our ocean only eats plankton and tiny fish, but that’s precisely what the whale shark does.
This graceful creature is one of the most fascinating animals on our planet, and we still have a great deal to learn about its life.
Hopefully, marine conservationists and scientists will be able to prevent further significant population reduction before it is too late and the incredible whale shark is gone from our seas forever.
British-born Dan has been a scuba instructor and guide in Egypt's Red Sea since 2010.
Dan loves inspiring safe, fun, and environmentally responsible diving and particularly enjoys the opportunity to dive with sharks or investigate local shipwrecks.
When not spending time underwater, Dan can usually be found biking and hiking in Sharm's desert surroundings.