Discover remarkable whale shark facts and its way of life. Learn how you can help save the incredible species.
If you watched Attenborough’s Blue Planet II, you’re probably familiar with the elegant and mysterious whale shark. One of the gentle giants of our oceans, scientists actually don’t know a huge amount about these enigmatic creatures. So what do we know? We spoke to Dr Simon Pierce, Co-Founder & Principal Scientist of the Marine Megafauna Foundation (MMF) and all-round whale shark expert, to find out a few whale shark facts:
It’s not a whale
Firstly, its name is a little confusing. Even though they don’t have big gnashing teeth, the whale shark is not a whale but a true shark. This means they breathe water and don’t have to come to the surface to breathe air like whales and other mammals.
They’re one of only three species of filter-feeding shark; the other two being the basking shark, which you’ll find in the colder waters of Europe and often up around Scotland, and the megamouth shark which tends to occupy the deep water and is seen by humans only very rarely. Whale sharks tend to like warm, tropical water and can be found in shallow feeding aggregations right near the surface. This means you can just jump in and snorkel with them in many parts of the world and don’t even need to be a qualified scuba diver.
It’s the largest fish in the ocean
While they’re not a whale, they’re called whale sharks because of their size. These huge creatures are the largest fish on the planet, reaching up to 18-20m in length and a weight of up to 34 tonnes. They grow very slowly and mature quite late. Whale sharks are not believed to mature until they are around 9m in size and about 30 years old. We don’t know for sure but scientists estimate their full life span is around 80-100 years.
Totally harmless – but they do have teeth
Like other sharks, whale sharks do have hundreds of tiny teeth in conveyor-belt-like rows. Their scientific name – ‘Rhincodon typus’ – actually means ‘rasp tooth’. However, these teeth are just an evolutionary remnant and don’t really serve any purpose. Because of this, whale sharks are totally harmless to humans and hold a huge ecotourism value with people travelling across the globe to see and swim with them.
They love their food
Whale sharks love food – so much so that Simon often affectionately calls them “oceanic labradors”. They feed on tiny prey such as zooplankton and sergestid shrimp, which they ingest by straining it from the water using their gills – sort of like a coffee strainer.
Whale sharks are very good at finding food. You’ve probably heard that great whites can smell three drops of blood from miles away. Whale sharks have a similarly strong sense of smell which they use to find plankton.
Once they’ve found their food, they have two different methods of feeding. Passive feeding – or ram feeding – is where they open their mouth and swim along, filtering everything through their gills as they go. Active feeding – or suction feeding – is where they sit in the water acting like a massive vacuum cleaner, sucking in all the water and gulping it down.
They filter seawater at a staggering rate. The average adult whale shark can filter around 600,000 litres of seawater an hour but will only gather a relatively small amount of plankton (just 2-3kg) from this amount. Because of this, they have to feed for over seven hours each day to get an average of 21-22kg of plankton in order to sustain themselves.
They have the thickest skin of any animal
A whale sharks skin can be up to 10cm thick – thicker than any other animal. Like other sharks, they have “dermal denticles”, which are the teeth-like things that make their skin rough and tough as well as repelling parasites. It also makes them really hydrodynamic; the US navy has been imitating shark skin to make their boats more fuel efficient in the water!
They have a very interesting pregnancy
We don’t know a huge amount about their reproduction as no-one has ever seen a whale shark give birth and only one pregnant female has ever been physically examined (in 1995).
She sadly died after being accidentally caught by a Taiwanese fishery and drowned because she was unable to keep swimming (which they need to do to be able to breathe) while caught in the net. The fishermen realised she was pregnant and gave her to scientists, who found 304 pups inside her.
When examining her, the scientists found something very interesting: the entire litter of pups were split into three different maturity stages – around 100 were still stored as eggs, the next 100 were in embryonic stage and the last 100 were almost ready to be born. Despite being at very different stages of development, all the pups had the same father so scientists believe that female whale sharks have the ability to store semen and impregnate themselves when ready to become pregnant!
They’re endangered but You can help with their conservation
Whale sharks are now classified as endangered on the IUCN Red List so the work MMF is doing to protect them is incredibly important.
How You Can Help Save Whale Sharks
The good news is, there are several things you can do to help now that you know these interesting whale shark facts:
Use responsible operators
If you’re swimming or snorkelling with whale sharks, make sure you join an operator that operates in a respectful, responsible and sustainable way and adheres to the code of conduct.
This was developed to ensure whale sharks were not hurt, disturbed or frightened by human encounters so will also enable you to have a more successful interaction with the shark
Submit your photos
Each whale shark has a unique pattern behind its gill slits and above its pectoral fin which means anyone who swims with whale sharks and takes a photo can help researchers identify sharks by submitting their picture to WhaleShark.org.
Through this global sightings database, citizen scientists can help researchers count how many sharks are seen and track their movements and behaviours over time.
Support marine conservation NGOs
The Marine Megafauna Foundation’s mission is to protect threatened marine life such as whale sharks. In Mozambique, the charity is teaching local children how to protect the ocean through a combination of marine conservation education, life-saving swimming lessons and Saturday activities like beach cleanups.
The Ocean Guardians programme has been a huge success but urgently needs public support to be able to continue.
By supporting this initiative, you will not only be helping to inspire a future generation of marine conservationists but also playing your part in protecting our ocean.