Whale shark diving
Whale shark = Rhincodon typus
Weight = up to 12 tons
Length = up to 16m
The whale shark is the biggest fish and shark in the world, it’s NOT a whale. These gentle marine giants roam the oceans around the globe, generally alone. However, large numbers of whale sharks often gather in areas with abundant plankton food—making them prime tourist attractions. Its enormous mouth (nearly 1.4 meter wide) engulfs large quantities of tiny plankton which it filters through its gills as it swims.
Whale sharks have an enormous menu from which to choose. Fortunately for most sea-dwellers—and us—their favorite meal is plankton. They scoop these tiny plants and animals up, along with any small fish that happen to be around with their colossal gaping mouths while swimming close to the water’s surface. The whales hark, like the world’s second largest fish, the basking shark, is a filter feeder. In order to eat, the beast juts out its formidably sized jaws and passively filters everything in its path. The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales.
The whale shark’s flattened head sports a blunt snout above its mouth with short barbels protruding from its nostrils. Its back and sides are gray to brown with white spots among pale vertical and horizontal stripes and its belly is white. Its two dorsal fins are set rearward on its body which ends in a large dual-lobbed caudal fin (or tail).
Preferring warm waters, whale sharks populate all tropical seas. They are known to migrate every spring to the continental shelf of the central west coast of Australia. The coral spawning of the area’s Ningaloo Reef provides the whale shark with an abundant supply of plankton.
Although massive, whale sharks are docile fish and sometimes allow swimmers to hitch a ride.
Whale sharks have about 3,000 very tiny teeth but they are of little use. Whale sharks are filter feeders who sieve their tiny food through their large gills.
Diet and Feeding Habits
The whale shark is a filter feeder that sieves small animals from the water. As it swims with its mouth open, it sucks masses of water filled with prey into its mouth and through spongy tissues between its 5 large gill arches. After closing its mouth, the shark uses gills rakers that filter the nourishment from the water. Anything that doesn’t pass through the gills is eaten. Gill rakers are bristly structures (the thousands of bristles are about 10 cm long) in the shark’s mouth that trap the small organisms which the shark then swallows. The water is expelled through the sharks 5 pairs of gill slits. The prey includes plankton, krill, small fish and squid. The shark can process over 6000 liters of water each hour.
Whale sharks are solitary creatures. Groups of whale sharks have only been rarely seen.
Whale sharks are slow swimmers, going no more than 3 mph (5 kph). They swim by moving their entire bodies from side to side (not just their tails like some other sharks do)
The Whale shark was long thought to be oviparous (an egg 36 cm long was found in the Gulf of Mexico in 1953. This would be the largest egg in the world.) Recently, pregnant females have been found containing hundreds of pups so Whale sharks are viviparous, giving birth to live young. Newborns are over 60 cm long.
Whale sharks are sexually mature at 30 years old. This is the age at which they are able to mate and reproduce.
Whale sharks are harmless to people and usually indifferent to divers.
It has been estimated that whale sharks may live up to 100 – 150 years.