The biggest fish on the planet is one of the creatures we know the least about. In the last century their numbers have halved; they could be disappearing, we could be running out of time together. It has always been there beside us but far enough away that we never had to interact, but now humans and whale sharks swim side by side on a fairly regular basis. The whale shark perplexes us in every way, even its name is conflicting: how can it be both whale and shark? What does it eat? Read below to find the answers to these questions and many more as we present you the whale shark!
Whale Shark: Whale or Shark?
Whales are a type of marine mammal, closer to us than to sharks. Like us, they are warm-blooded, they breathe air through nostrils (for them, a hole on top of their head), and the females nurse their young with milk.
Sharks on the other hand are technically fish. They are cold-blooded, breathe through gills, and, although they give live birth unlike most fish, females do not produce milk for their young.
So how is a whale shark classified? A whale shark is 0% whale and 100% shark. The whale part of the name comes specifically from the massive size of the animal.
And these guys are BIG: the largest on record measured at 61.7 feet! Adults average between 18 – 32.8 feet and weigh in around 41,000 pounds.
This makes the whale shark the world’s largest fish.
Do whale sharks have teeth?
300 rows of teeth line the whale sharks mouth, but not the kind of teeth we usually associate with a shark.
If normal shark teeth look more like the teeth on a large saw blade, whale shark teeth have more in common with the teeth of a rasp: more like sandpaper than a saw. They don’t use these teeth to eat: we cannot explain their purpose at this time and consider them vestigial.
How do whale sharks eat?
Rather than eat with their teeth, whale sharks eat by essentially using their mouth as a giant sieve. Water comes in through its mouth and out through its gills, passing through and around the 20 filter pads between its gaping jaws. These pads filter and redirect smaller particles back out while allowing larger items to continue down the shark’s throat.
Basking sharks, another massive shark and the second largest fish, also fall into this category of filtration feeders. These giants swim with their mouth wide open and sweep up any food in the water. As long as there is food in the water and the Basking shark swims, it is eating.
The whale shark has a special advantage. It can feed like the Basking shark, by swimming with it’s mouth open, a method called “ram filtration;” it can also feed without swimming, sucking water in by opening and closing its mouth, or “active suction feeding,” something the Basking shark cannot do.
Using either method, the whale shark actively pursues concentrated areas of plankton, krill, fish eggs and even eats small fish and squid.
Fun Fact: Whale sharks have a top speed of about 4 miles per hour
Where They Live:
The whale shark lives in tropical oceans around the world between 30°N and 35°S. They prefer water 70° F (21° C) or above near reefs and atolls.
Visitors can see them anywhere from Mexico and Belize to Australia and the Philippines during established “whale shark seasons,” provided they take a boat to the deeper water where these huge beings live.
We know little about these animals, but we believe their migratory patterns are largely influenced by the search for food, particularly plankton.
Whale sharks have been endangered since 2016 when we realized their numbers had dropped 50% in 75 years.
We believe this to be primarily a result of habitat loss, as our oceans around the world are rapidly dying. It may also be due to over-fishing of reef fish and targeted fishing of whale sharks themselves for their meat and for fins to use in the notoriously wasteful shark fin soup.
Aquariums in more concerned areas have raised awareness by rescuing whale sharks destined to be eaten and giving them a new home and longer life in the public eye. This was, for example, the case for the two whale sharks which recently died at Georgia Aquarium: Alice and Trixie.
Fun Fact: International whale shark day is August 30
Whale Sharks and Humans:
When was the whale shark discovered?
We do not know when the whale shark was first discovered, as humans have traveled the seas for millennia and have undoubtedly seen much more than they recorded. We do know that it was first scientifically recorded, to our knowledge, in 1828 by Andrew Smith off the coast of South Africa.
Are whale sharks dangerous?
With a mouth 5 feet wide and a proportionately huge body, you may very reasonably ask if whale sharks are dangerous. At the back of these gaping jaws is a throat the size of a quarter; a whale shark could not swallow a human even if it wanted to. The huge mouth is more like a funnel, capturing as much plankton filled water as possible to direct it down this tiny throat.
As big as they are, and as fearsome as their relatives may be, many cite that whale sharks have never been known to attack any humans. I suppose in this way – their gentle mannerisms – they do in fact resemble whales. They generally come across as very passive and tolerant, slow moving creatures. As far as fish go, and certainly sharks, the whale shark is friendly to humans.
This is one reason whale shark tourism has gained a foothold, though this tourism is a double-edged sword. Though it increases awareness of this endangered species, tourism is speculated to contribute in a small way to their endangered status, with snorkelers potentially interrupting their feeding and reckless boat drivers hitting them with their propellers as the sharks feed near the surface.
Now, I mentioned above that many claim whale sharks have never attacked humans. This could be called the rule, but to every rule there is an exception, especially when dealing with wild animals.
Historically, humans have had little physical interaction with whale sharks due to their habitat being further from shore. To swim beside a whale shark, you need to intentionally go to where they are.
We need to remember these are huge and independently conscious wild animals: they have no law forbidding them from attacking us.
As mentioned above, their tiny throat makes them incapable of eating humans. However, like any animal, when threatened they are entirely capable of becoming unpredictable and violent.
There is one story of a woman, an experienced diver, who was half-swallowed by an agitated whale shark before it spit her back out (source)
To bring it to a more positive note, the woman had no serious injuries, so even a violent and agitated whale shark is a relatively harmless giant, even when not being so gentle, but perhaps as human interaction with them increases we may see more accounts.
So, while whale sharks are a species friendly to humans and renowned for their gentle and passive nature, they are, like any animal, unpredictable and capable of violence and warrant a respectful and cautious demeanor.
The whale shark is a beautiful and amazing creature, as mysterious as it is fascinating. Whale sharks are a sign of health in the ocean, as they show that their food source, life on the smallest of levels, is abundant enough to feed their giant bodies. However, the decline of whale shark populations indicates to us the decline of all life in the ocean. There is hope for them as a species if we can come together and take care of the oceans of our planet, which in turn will take care of us as they always have.