The whaleshark (Rhincodon typus) is the largest of the elasmobranchs, reaching up to 18 metres in length and weighing around 11 tons. It has around 6,000 teeth, which are barely 2mm long and appear to be vestigial. Whalesharks don’t use their teeth to capture prey, but instead, they filter large amounts of water through specialized gills.
Despite being the largest fish in the ocean, it curiously feeds on the smallest food: plankton, made up of thousands of microscopic beings such as protozoa, tiny crustaceans, mollusks, worms, and fish larvae.
That is precisely what draws the whaleshark to the stern of the dive boats.
The secret of the visit
A few years ago, the local fishermen revealed their secret! While they used to fish for sardines and other species at night, using a great light as an attraction, they realized that somehow, they were attracting the giants of the ocean! At night, the light attracts plankton, which attracts the whaleshark. But why does light attract plankton? Well... at night, zooplankton organisms, such as copepods, migrate vertically into shallow waters to feed on phytoplankton (microscopic algae). Since phytoplankton needs sunlight to grow, it’s concentrated in the first layers of water; and zooplankton organisms take advantage of the night feed as they can’t be seen by their predators (small fish, for example). But when humans introduce artificial light - bam! Small fish can see the copepods and begin to eat them.
Larger fish can also see these small fish and eat them, and eventually top predators can jump into the action and enjoy a good feast. And that’s when our star of the night appears - the magnificent whaleshark. Sometimes we can see up to three or four together. And recently, a group of very lucky divers swam with 11 whalesharks on the central route!
Did you know?Although these huge sea creatures are called ‘whalesharks’, they are not actually whales, but filterfeeding sharks, often referred to as ‘gentle giants’. They are also the world’s largest fish, growing up to 18 metres long.Essential informationLocation: Maldives Depth: 1m-3m Diver level: Beginner Who to dive with Blue Force Fleet www.blueforcefleet.com
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USNS General Hoyt S Vandenberg
Scuba Diver Magazine
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