Whale sharks are the largest of any fishes alive today. Galapagos is arguably the very best place in the world to dive with these magnificent giants of the deep. Whale sharks inhabit all warm and temperate seas on the planet yet are an elusive species to find. The Galapagos islands are an important stopping off point on the migratory path of whale sharks, making them one of the most reliable places on the planet for whale shark observation.
These huge creatures are reportedly capable of reaching a maximum length of about 18 metres (59 feet). Most specimens that have been studied, however, weighed about 15 tons and averaged about 12 metres (39 feet) in length. That’s still bigger than a classic transit bus! Despite their size, whale sharks are referred to as ‘gentle giants’. Whale sharks are filter feeders and can neither bite nor chew. They can process more than 6,000 litres of water an hour through their gills! Although its mouth can stretch to four feet wide, a whale shark’s teeth are so tiny that they can only eat small shrimp, fish and plankton by using their gill rakers as a suction filter. Whale sharks travel immense distances around the globe in order to exploit rich food patches. In an average year a shark could travel 10,000km in its constant search for food. This distance is made even more impressive by the fact they move at speeds of little more than three miles per hour. They are a surprisingly inefficient swimmer and need to use their entire body in the act of swimming – something that is very unusual for fish species
The upper surface and flanks of whale sharks are grey blue in colour and covered with a pattern of white spots. Like fingerprints in humans, these spots are unique to individuals, enabling researchers to identify and track different whale sharks. Their distinctive spots have led to local names, such as ‘marokintana’ in the Malagasy language in Madagascar which means ‘many stars’.
A lot is still unknown about these mysterious creatures. For example, we are still unaware of the locations in which they give birth. We do know, however, that they are ovoviviparous, which means their embryos initially develop inside an egg that they emerge from whilst still inside the mother, resulting in the birth of live young. For those that are born, it’s thought that less than 10% survive to adulthood, but those that do may live to 150!
Whale sharks congregate in the far north-west of the archipelago at Darwin and Wolf Islands. You can also observe whale sharks on the Islands of Isabela and Fernandina. The waters around Darwin’s Arch are a particularly popular whale shark feeding ground, where naturally upwelling currents attract plankton. The principal Galapagos whale shark season is from June to November, with peak viewing usually during August and September. During this time the cold Humboldt current flows into Galapagos water from the south, cooling the ocean and bringing rich nutrients that are perfect for all marine species. Although many whale shark individuals spend no more than one day here before moving on, some do choose to stay for a longer period. Whale shark behaviour is unpredictable, so sightings are also highly possible at other times of year. Of the individuals who visit the islands, 90% are pregnant females. Again, little is understood about this unusual behaviour. For a chance to swim alongside these mysterious and enigmatic giants of the sea, come and visit the Galapagos!