Did you know?
Whale Sharks can grow up to 12 metres (40 feet) long and weigh more than 20 tonnes
Whale Shark Facts
How the whale shark got its spots
The tribes of Mozambique tell a story whereby one of the gods was visiting Earth and saw a whale shark swimming by in all of its grace and beauty, under the water near his boat. In appreciation, he showered the whale shark with silver coins, which became the spots all over its body.
It is thought that whale sharks have lived in the Earth’s oceans for literally millions of years, dating back to the Jurassic period. (I.e. they have been around a whole lot longer than we have been!;-)
The whale shark is the world’s largest living fish/ shark, however, very little is still known about the biology and ecology of the whale shark. Until the 1980s, there had only been 320 confirmed sightings worldwide!
It is believed that Whale sharks can live around 100 years, reaching maturity at around 30 years of age. The largest non-scientifically recorded whale shark was around 18 metres in length, however on average they reach sizes of up to 12 metres. In the Ningaloo the most common size of Whale shark is around 4-6m, with some getting up to 10m. (A 12 metre shark may weigh as much as 11 tonnes and have a mouth over 1.5m wide!)
Whale sharks can be identified by three prominent ridges along each side of their body and a distinct pattern of white spots and stripes against a dark blue/grey skin. The skin on the back of the whale shark is thicker and tougher than that of any other animal in the world. The outer layer is covered in overlapping dermal denticals, like a suit of armor. The spots and stripes on the whale sharks are for camouflage, by reflecting and dispersing light their outline is harder to make out to predators.
Whale sharks have been reported in tropical and warm temperate seas. They are found in a band around the equator, in water temperatures of 18°C to 30°C, and in both coastal and oceanic waters. In Australia, whale sharks occur mainly off northern Western Australia, the Northern Territory with some reports in Queensland.
The diet of Whale sharks consists primarily of plankton, krill and other small organisms. Whale sharks regularly appear at locations where seasonal food ‘pulses’ occur. For example, at Christmas Island, off Western Australia, the appearance of whale sharks is linked to a red land crab-spawning event. In Belize, whale sharks feed on snapper spawning events. Many researchers believe that whale sharks ‘migration’ patterns could be a food-driven, however, there is currently limited evidence to support this theory. Other theories include that Whale sharks move offshore for breeding and birthing, again however, there is limited evidence to support this.
Whale sharks are generally encountered singly, but aggregations of over a hundred animals have been seen, which suggests that schooling does occur. Ningaloo Reef, in Western Australia, is one of only a few places in the world where whale sharks appear regularly in near-shore waters in number, where they are easily accessible to observers. The whale sharks swim and feed in the waters around the Ningaloo Marine Park from March to August/September before disappearing from the area for another year. Some years they have been known to remain in the area in to October.
In 2013, an aggregation of over 20 whale sharks was seen off the Muiron Islands.
Whale sharks are ovoviviparous (this means the egg cases hatch in utero, so the female gives birth to live young) although the period of gestation is unknown and the number of live born also remains unclear. Female whale sharks may carry up to 300 embryos, and their young are born at around 50cm. The sexual maturity in both sexes may not occur until sharks are about eight metres in length. It is still unknown how often whale sharks reproduce or even where they go to mate or give birth. Only male whale sharks have claspers—this is the only visible way to tell the difference between male and female whale sharks.
There is very recent emerging evidence suggesting a significant number of whale sharks may give birth off the coast of Southern India, However, as per much of our knowledge about them, facts are imperfect or suggestions rather than conclusions at this stage.
Tracking Whale Shark with Ecocean
Very little is known about Whale sharks and their migratory patterns. Ecocean is an organisation devoted to learning more about the whale sharks, one of the main ways they do this is by identifying the sharks and where they are sighted.
Each whale shark has an area just behind their gill slits and just above their pectoral fin where their markings are completely unique, like a human finger print. Ecocean has a database of photographs of identified whale sharks.
Ecocean have adapted a software program from NASA. The software is used by NASA to identify star constellations, but has been adapted to identify the markings on whale sharks.
Anyone is welcome to send any clear Whale shark photo to Ecocean and Ecocean will let you know if this is a new whale shark or one that has been recorded before as well as details such as location of sightings, size etc. However, to save Ecocean getting 20 pictures of the same shark, after every Whale shark tour our videographer will send in a picture of each whale sharks on your behalf. You can log onto the ECOCEAN website www.whaleshark.org and look up the details of the sharks from the date of the Whale shark tour you went on. Ecocean will also update you every time that your whale shark is seen in the future so you can see where they have got to!