Diving with Whale Sharks
Swim with Whale Sharks
If you have been there then you know. If you haven't, then it is difficult to describe the feeling of sharing the water with this, the biggest fish in the sea. More like a whale than a shark, these fish are right at the top of most divers "To do..." lists. The best dives in the world for swimming with whale sharks have been visited by Dive The World and you could go there too. Find out more about the mighty whale shark and make your dreams come true ...
While some people are intimidated by its size, the whale shark is actually a gentle giant keen to avoid confrontations and generally trusting of humans. As for etiquette when diving with a whale shark, it is said that passive interaction is the best policy.
In fact, aggressive behaviour can drive them away - so no touching, or swimming after them if you're hoping for one to hang around you. They can be quite friendly. One of our satisfied customers said the encounter had demonstrated distinctly more mammalian than fishy behaviour.
Whale shark Fact Sheet
Family name: Rhincodotidae
Order name: Orectoloboformes
Common name: Whale shark
Scientific name: Rhincodon Typus
Distinguishing Features
Considered the biggest fish in the world, the whale shark is a cold blooded cartilaginous fish like any other shark. It breathes through gills. Its tail is vertical and moves from one side to another when it swims, unlike other warm-blood animals (mammals) which have parallel tails and breathe through lungs like the whale, dolphin and dugong.
Whale sharks can weigh over 9 tons and grow up to 12 metres in length, although there are questionable, unconfirmed sightings of specimens up to 18 metres in length. They can generally be found in the entire Indian Ocean in depths of up to 130 metres.
The whale shark is easily recognised by its immense size and a 2-tone pattern of light spots and lines on a dark brown dorsal surface. Unlike that of most other sharks its enormous mouth is terminal in position and can be opened wide to filter large amounts of water for small fish, squid, crustaceans, and other plankton organisms.
The whale shark's skin can be over 10cm thick.
Behaviour
Not much is known about the habits of these animals. Adults tend to be solitary and nothing is known about how they find each other. Young whale sharks of less than 3 metres live in small groups, but are rarely seen. It is thought that they spend most of their time in the great ocean depths to negate their increased vulnerability. It is unknown what they eat during this time.
Encounters with whale sharks are virtually guaranteed in several parts of the world at the right season - namely, in the Philippines, off the Seychelles, Christmas Island, South Africa, Mozambique, Belize, Honduras, Mexico and Western Australia.
Whale shark sightings are common in Thailand too, especially on dive tours around the Andaman Sea and at Richelieu Rock. Numerous customers wonder in asking us about the chances of coming across a whale shark around Phuket. The answer is very high, especially between the months of February and May every year.
Feeding Habits
These filter feeders eat plankton, krill, fish eggs, small fish, salp, jellyfish and coral spawn. They are known as harmless fish and present no threat to either man or the fish that school around them. In fact, their small teeth play no role in feeding at all.
Food enters the whale shark's mouth by being sucked in. The water is then discharged via the gills and plankton and other specks of food, anything bigger than 2 to 3mm in diameter, are trapped against the dermal denticles.
The whale shark's dermal denticles are like sieves, which only let water and very tiny particles through. Everything else is swallowed as food. Every now and again the whale shark coughs, an action scientists believe is to clear the dermal denticles of food build-up.
The whale shark can take in water through forward motion with its mouth open, but can also gulp in water when it's in a stationary position.
Reproduction & Life Cycle
Details about reproduction and life cycle of whale sharks are few and sketchy. As recently as 1956 it was believed that whale sharks were oviparous because of the discovery of a solitary egg sack in Mexico.
However, inside a pregnant whale shark that was killed by fishermen in 1995 in Taiwan, over 300 embryos where discovered, ranging in length from 40 - 60cm.
Based on that discovery it was deemed that whale sharks are ovoviviparus, because although egg pouches are formed, they stay within the mother's body with no further nutrition from the mother, until they hatch and are born live.
Because of this single whale shark, it is estimated that they reach sexual maturity in their 30's. But much remains a mystery, such as where they go to mate, how often they mate or reproduce, or where they go to give birth.
It's generally accepted that whale sharks can live to be over 100 years old.
Predation
Other than the ever present threat from man, the adult whale shark has no natural enemies.
Distribution
What little is known about the migration patterns of whale sharks is known because of the tagging of a few individuals.
In general, whale sharks prefer the tropical regions around the world with warmer waters between 18 to 30°C where plankton abound, although they have also been recorded to dive deeper than 980m to where the water is as cold as 10°C.
Whale sharks are in pretty much a constant state of migration, presumably going where the food is, which spans a large area.
As yet, no whale shark mating sites have been found and scientist can therefore only speculate about such things as whale sharks being pretty much loners, only getting together when they mate.
Ecological Considerations
Unfortunately, the planet's largest fish is on the verge of extinction. The World Conservation Union lists them as 'Vulnerable'. In Taiwan, documented catches have declined by 50 to 80% from the mid-1980's to 1990's. In Gujarat, India, 160 whale sharks were landed between January and May 2000 compared to 279 within the same time the previous year. In Thailand, sightings of whale sharks have also declined significantly.
Why is this so, you might wonder? Well, whale sharks are extremely vulnerable to over exploitation by man for several reasons. They have a slow growth rate, only reaching maturity at around 30 years old and living as long as 60 - 100 years. Their reproduction rate is also very slow - long intervals between pregnancies and producing around a few hundred pups at one time. Quite simply, the whale shark cannot populate fast enough to keep up with man's consumption.
Whale shark meat and fins are considered gourmet cuisine in some Asian markets where a single fin can fetch up to US$ 10,000. A restaurant in Beijing once sold three fins from whale sharks for over US$ 72,000 in November 1999.
A number of non-profit organisations have been campaigning tirelessly to protect the world's largest animal from overexploitation and the very real threat of extinction. Some of them are Wildaid, the U.N. Convention on International Trade in Endangered Species (CITES), and in Thailand, the Save The Whale Shark for the Thai Seas Conservation Club.
Dive Sites
More detailed information on whale shark diving destinations:
Australia
Burma - Myanmar
Indonesia
Malaysia
Maldives Islands
Thailand
Dive The World Recommendations: Richelieu Rock and Hin Daeng in Thailand, Ari Atoll in the Maldives, and the Burma Mergui Archipelago.
• Send for your diving holiday options
Back to creature features index |
