Worldwide in tropical latitudes
Coastal to open ocean (pelagic); sometimes aggregate around specific reefs or beaches
Order Orectolobiformes (carpet sharks), Family Rhincodontidae (whale sharks)
The largest fish in the world is the graceful, harmless whale shark. Though they reach the size of a school bus, whale sharks eat tiny plankton and fish eggs, which they filter feed as they swim slowly along with their giant mouths wide open. They are one of only three species of filter feeding sharks.
Their incredible size may help them to survive long migrations to abundant food sources, between which they may not be able to find enough food. Scientists believe that some individuals swim across entire oceans to arrive just in time for a plankton bloom or a mass spawning of fish or coral eggs – an amazing feat for a fish.
As opposed to the other large sharks, which give birth to a small number of very large babies, whale sharks give birth to hundreds of very small babies (approximately 20 inches/45 cm). Even more interesting, after internal fertilization, the female whale shark actually produces hard, reinforced egg cases but then keeps them safely inside her abdomen until they hatch, at which point she gives live birth. The energy required to produce the unnecessary egg cases could perhaps be better utilized to produce more young, though it is possible that under some circumstances, the female deposits her eggs to hatch on their own.
Whale sharks are also unique in that they are covered with white spots, and every individual apparently has its own spot pattern. In fact, whale shark researchers utilize specialized computer software, originally designed for star mapping, to identify individual whale sharks from photos of their spot patterns. Using this technology, researchers will be able to tell if individuals that are photographed by tourists in Mexico are later photographed by fishermen in Belize, for example.
Like many large, slow moving animals, the whale shark has been fished quite heavily over the last several decades, and individuals are often accidentally caught in fishing gear that targets other species. Whale shark meat is eaten in some parts of the world, and the fins are valuable as well. Scientists currently believe whale sharks to be vulnerable to extinction. Fortunately, a large tourism industry has been developed for viewing whale sharks in the wild, and their value alive is higher than their value to fishers. For that reason and because they are such impressive animals, most places around the world offer whale sharks complete legal protection. Unfortunately, illegal fishing does still occur in some places.
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.