I’m working on this page RIGHT NOW (like, today), so I hope you’ll come back soon to read all the new information. Until then, please bear with me as the text below is being edited.
Welcome! I’ve created this page to present some interesting whale shark facts, answer the most frequently asked questions about whale shark biology, show you some pictures of whale sharks, and to explain the research we’re doing to learn more about these gentle giants, the world’s largest fish.
Why am I the right person to write this? I’ve been studying whale sharks since 2005, written lots of scientific papers on whale shark biology and ecology, led the global conservation assessment of whale sharks in 2016, and am currently writing a textbook on whale sharks (for publication in 2019).
Wait, so is a shark a fish?
Yes! Sharks are fish, but they’re quite different to “normal” fishes, which have a skeleton made out of bone. In fact, they’re not closely related. Sharks are an ancient group whose direct relatives first appeared about 395 million years ago. Sharks, rays and chimaera have a skeleton made out of cartilage, the same material as in your ears and the end of your nose. The cartilaginous fishes evolved totally separately to bony fishes.
So yes, sharks are fish, but “fish” is an unnatural grouping: birds and reptiles are far more closely related to one another than sharks are to bony fish.
What is a whale shark?
The name “whale shark” often confuses people: is a whale shark a shark, or are they mammals? Just to add to the bewilderment, they’re sometimes called shark whale or whale fish as well. Sigh.
Whale sharks are a true shark. The name “whale shark” just comes from their huge size, comparable to a lot of whale species (which are mammals, like us). Sharks are fish, although see above – that’s a bit confusing too. Anyway, whale sharks are in the order Orectolobiformes along with 42 other species including the nurse shark and the zebra shark, their closest living relatives. You can visualise the relationship on the Chondrichthyan Tree of Life website.
Nurse shark photo
Leopard shark photo
The whale shark is the only species in the family Rhincodontidae, and the earliest fossil records for whale sharks are about … million years old. The scientific name of a whale shark is Rhincodon typus.
The largest shark: how big is a whale shark?
Whale sharks are the largest of all shark species, and the largest fish as well. People have always been fascinated by whale shark size, so there is a lot of confusion online about the length of the biggest ever whale shark. The largest whale shark that has been measured was 20 m (65? ft) in length. 18.8 m.
How much does a whale shark weigh?
How long is a whale shark compared to other large marine species?
whale shark vs basking shark
whale shark vs blue whale
At this stage, whale sharks are thought to be the largest fish that have ever lived.
I’d compare them to a bus, but they make a bus look like a… erm… minibus. The largest whale shark measured was 20 m long, and they reach at least 34 t. School buses are only about 14 m long, and 16 t. Pah. Among all animals, only some of the true whales (which are mammals) are larger.
Are whale sharks dangerous?
whale shark attack
whale shark eating people
do whale sharks eat humans
Add the ‘what would happen if you got swallowed’ answer…
In saying that, they’re enormous fish. Add the picture of Chris shaved?
Whale shark predators
What would eat a 20 m shark? Well, not much actually. When we talk about whale shark predators, we are generally referring to smaller whale sharks.
Whale sharks have the thickest skin of any animal. This, and their huge size, provide some protection from most marine predators. Only a single species, the killer whale, is known to kill adult whale sharks.
Do whale sharks have teeth?
Yes, whale sharks do have teeth – they’re just small. Whale shark teeth form… rows… about 1 mm high…
Swimming with whale sharks
whale shark diving
Whale sharks are one of the most popular species with marine tourists.
What do whale sharks eat?
Zooplankton and small fish.
whale shark diet
whale shark mouth
largest plankton-feeding fish
Whale sharks eat zooplankton. Even though their mouth is a couple of metres wide, they can feed on fish eggs of less than a millimetre in diameter.
A medium-sized whale shark filters over 600, 000 litres of seawater an hour. To put that in perspective, it’s like 600, 000 litre bottles of milk. Which would make around 40 million cups of tea. And that’s a lot of tea.
Where do whale sharks live?
From Canada to NZ, >21C water.
whale shark habitat
whale shark season
Jacques Cousteau only ever saw two. And that’s after a lot of ocean exploration, and downing a lot of red wine. Before they were discovered to predictably feed in certain locations – off Ningaloo Reef in Australia, in the middle of Qatari oil fields, even offshore from Cancun in Mexico – they were one of the least understood large animals in the ocean. Whale sharks were only documented by science in 1828, and only 320 encounters had been recorded by the 1980s. Now, though, it’s possible to find hundreds!
Whale shark migration
Whale sharks are true ocean wanderers. They routinely swim over 10, 000 km each year.
Whale shark lifespan
Best guess is 80-100 years. Haven’t been able to age them properly – bomb dating, or perhaps wild growth rates.
Us scientists estimate that they reach 100 years old or more. Compare that arbitrarily to the greater flamingo, which reaches the measly age of… 83. Wait, seriously? Well, whale sharks still get older. And they probably don’t even become adults until they are over 25.
Whale shark reproduction
baby whale shark
Whale sharks have the most babies of any shark. The single pregnant female that has been examined by scientists, taken in a fishery off Taiwan in 1995, had 304 baby whale sharks inside her. The babies are born free-swimming at 40-60 cm long, and likely get no further assistance from their mother.
How deep can a whale shark swim?
Whale sharks are incredible deep-divers. 1928 m so far. well over a mile in depth.
What are they doing down there?
Are whale shark endangered?
Most of my work at the Marine Megafauna Foundation focuses on Earth’s largest fish, the whale shark. Whale sharks are – in every sense of the word – awesome. They’re also seriously under threat. Whale sharks feed solely on zooplankton and small fishes and are totally harmless to people.
Sadly, their gentle nature has been exploited by targeted fisheries and additional high levels of bycatch. The whale shark is now a globally endangered species and, without active conservation measures, we could lose them forever. That would be a tragedy.
Whale shark population ecology
My whale shark research began in Mozambique in 2005. Not much scientific work on whale sharks had been published at the time, so the first task was to work out *how* to research them. Fortunately, every single whale shark has a distinctive pattern of white spots on their upper surfaces and, by taking photographs of each flank, we can reliably identify individual sharks over time. That means we can count how many sharks we see and track their movements and behaviours.
All whale shark researchers are using the same area of the sharks’ body for photo-ID. This has become a global effort thanks to the Global Whale Shark Photo-ID Library. Over 8000 individual whale sharks have now been identified, from over 50 countries. Many of these identification photographs have been submitted by the interested public. This database represents a notable success for ‘citizen science’.
Because each individual has a unique spot pattern, photos can be used to count the number of whale sharks in the world. Over 4000 tourists and researchers have submitted photos to a global sighting database (www.whaleshark.org), identifying over 5400 whale sharks from 36 countries.
How big are whale sharks?
Whale sharks are really big. In practical terms, that makes it hard to get accurate measurements of how large they actually are. To get around this, we mounted green laser pointers on either side of the camera we use for photo-ID. That gives us a ‘scale bar’ on the resulting photo, and means that we can see who the shark is, and how long they are, with a single photograph.
You can see this measuring system in the photo above. There’s more detail on the technique here. We’re starting to move towards stereo-video now to improve the accuracy further.
We can also collect tissue samples from the sharks using a biopsy pole, allowing us to
What are the goals of our research?
How many subpopulations are there?
Key threats to each subpopulation
Protect high-value aggregation sites
Improve ecological understanding of size- and sex-based segregation
Whale shark are a very popular species with marine tourists, and there are several sites where sharks, particularly juvenile males for some reason, can be seen fairly reliably each year. I think that tourism has been largely positive for whale sharks, creating an economic incentive to ensure that they are managed well, but it has led to the need to evaluate the impacts of swimmers on the sharks.
We have done considerable work on this, both in developing science-based codes of practice and monitoring protocols and conducting guide and skipper training in Madagascar, Mozambique and (with Sea Sense) in Tanzania.
‘Team Whale Shark’ at MMF
We have a great team in Mozambique, and now around the world. Pete Haskell completed his MSc (Distinction) on whale shark tourism in 2010. Dr Chris Rohner, my first PhD student, finished his doctoral thesis on Mozambican whale sharks in 2013 and has been leading our project at Mafia Island in Tanzania since 2012. Clare Prebble joined MMF as a Project Manager in 2011, has been running day-to-day operations in Mozambique since 2012, and is now also a PhD candidate at the National Oceanography Centre at the University of Southampton, UK. I’ve also had some fantastic long-term project assistants over the last few years, including Peter Bassett (who has now started Aquatic Alliance in Indonesia).
Dr Chris Rohner assessing the maturity of a male shark
Where do we work?
As of 2017, we work in…
- The Arabian Region with Sharkwatch Arabia .
- Ecuador (Galapagos) with the Galapagos Whale Shark Project.
- Madagascar (Nosy Be) with the Madagascar Whale Shark Project.
- Mexico (Quintana Roo) with Ch’ooj Ajauil AC.
- Mozambique (Inhambane) with the Marine Megafauna Association.
- The Philippines (Tubbataha Reefs Natural Park and elsewhere) with the Large Marine Vertebrates Research Institute.
- Tanzania (Mafia Island) with WWF Tanzania, TAFIRI and KAUST.
We also have global collaborations underway on biochemical and genetic analysis projects.
I try to keep up a running commentary on our fieldwork here on my shark biology blog, and if I’m behind on that material there’s still a good chance I’ve been procrastinating on Instagram or Facebook.
What have we achieved?
Whale shark off Mafia Island, Tanzania
Unfortunately, even though some of the largest fisheries for whale sharks have now closed – generally after running out of sharks to catch – there are still serious human threats to whale shark populations. We need to provide effective protection to their key habitats. We’re lucky in that whale sharks, with their huge size and placid natures, are very popular with marine tourists. We are working with the tourism industry to ensure that these activities are sustainable.
How is this work funded?
Want to join us in the field?
If you’d like to participate in this work, we do public research expeditions each year.