Swimming with the Whale Sharks

The whale shark is the biggest fish in the world, reaching lengths of 40 feet or more.  It is not a whale. It has a huge mouth which can be up to 4 feet wide.  It's mouth is at the very front of its head and not on the underside of the head like in most sharks. Fortunately for 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 enormous whale shark is a filter feeder and sieves enormous amounts of plankton to eat through its gills as it swims.  The whale shark is up to 46 feet, weighing up to 15 tons.  The average size is 25 feet long. Females are larger than males, like most sharks.  Whale sharks have about 3,000 very tiny teeth but they are of little use since they are filter feeders who sieve their tiny food through their large gills. As it swims with its mouth open, it sucks masses of water filled with prey into its mouth and through spongy tissue 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 4 inches 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 1500 gallons of water each hour.

Whale sharks are slow swimmers, going no more than 3 mph. They swim by moving their entire bodies from side to side (not just their tales, like some other sharks do).  Whale sharks give birth to live young that are over 2 feet long.  Whale sharks are sexually mature at 30 years old when they are able to mate and reproduce. It has been estimated that whale sharks may live up to 100 - 150 years.  Although massive, whale sharks are docile fish and are harmless to swimmers.  This was my second whale shark trip and again they came so close, that I had to push off them as they came right up against me and pushing me to the side. They actually seem curious of people and don't shy away from coming up to you. This is Djibouti, whale sharks, and the beauty of the Djibouti reefs where the whale sharks feed.