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Monday
Apr102017

Animal Profile - Whale  Sharks

Between 700,000 and 1 million species of animals live in the world’s oceans, with over 9 million thought to be undiscovered. So, who is the whale shark and why is it so important in a world of vast splendour?

Contrary to the name, they’re not whales at all. They’re fish – a species of carpet shark and are the largest shark in the world. The largest ever recorded was a whopping 40 feet long and weighed around 21.5 tones. Nonetheless, it is thought that the species can grow even bigger. Don’t worry though; the whale shark is the gentle giant of the ocean. They are filter feeders, making them completely harmless to humans. Their throats are only as big as a grapefruit. The whale shark places its jaw wide open and passively filters everything it comes across. They push out all of the seawater and feed on the plankton or other small crustaceans in the sea. This process is known as cross flow filtration. The only two other sharks that feed in this way are the basking shark and the megamouth shark.

What is pretty cool is their teeth! Each whale shark has 3,000 tiny little teeth in its mouth; all over 350 rows! Sounds scary, right? Well, they don’t use them! The true function of these teeth is unknown whilst scientists remain fascinated by them.

By D Ross Robertson [Public domain], via Wikimedia CommonsThese epic sharks spend most of their time swimming slowly at the surface of the water. This doesn’t stop them from plunging into the deep though as they have been recorded diving as deep as 700 metres. They swim all over the world but are most commonly found throughout tropical waters surrounding Australia, Galapagos, Belize and Fiji. These guys also prefer to swim alone, which you’d think could get lonely for an animal that has a lifespan of up to 100 years but occasionally they will gather in large groups. In 2011, more than 400 of these sharks gathered off the Yucatan Coast. This was the largest gathering of whale sharks ever recorded.

Out of around 400 species of shark, just 40% lay eggs. Whale sharks are in the majority, having internal fertilization allowing them to produce live young. The term for this is called ovoviviparous.  As only one pregnant whale shark has ever been recorded, it is unknown where these sharks breed. However, we do know that one female can have up to 300 pups! Luckily for the mother, they aren’t all born at once! The female will produce a large number of pups over a prolonged period. Phew!

flickr | Mike JohnstonAs widespread as these beautiful marine creatures are, we haven’t been aware of them for too long. The first ever whale shark was discovered in 1828 by Andrew Smith just off the South African coast. Yet the origins of this shark pave way back to the Jurassic and Cretaceous periods 245-65 million years ago. They’re also closely related to bottom-dwelling sharks (Orectolobiformes), which include  nurse sharks (Ginglymostomatidae) and wobbegongs (Orectolobidae).

Currently, they are listed as vulnerable on IUCN’s red list as the population is declining. Unregulated fisheries pose a threat to their numbers as many people hunt for their meat and fins. They’re also victims of bycatch. Conservation programmes exist to help preserve the species. Each whale shark has a set of spots located around their gills. Each pattern of spots is unique to each individual, just like a humans fingerprint. This allows researchers to easily identify individuals by photographing the sharks and cross-referencing their spots. As of 2016, there were recorded to be around 7,000 whale sharks in the ocean.

flickr | saf2285The value of whale sharks is often overlooked. These beautiful creatures play an important role in the oceans, indicating the health of ecosystems and ocean habitats. If you want to help make a difference and safeguard these animals, then get involved with our Mozambique Whale Sharks project.

By Simone Kelly - Online Journalism Intern

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