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Of the 32 shark species of Galapagos, the massive Whale Shark (Rhincodon typus) is by far the largest. These gentle giants of the ocean are, in fact, the largest living fish in the world. While they're found in the majority of the planet's warm and tropical oceans, the Galapagos Marine Reserve – which encompasses the waters surrounding this unique archipelago – can boast an interesting phenomenon as the region is particularly attractive to pregnant females of the species. For anyone planning a visit to this unique island chain, learning more about the shark species of Galapagos is vital to a comprehensive wildlife watching experience. Physical Characteristics The clue is in the name (although they are most definitely not whales) and these huge sharks can grow up to 18 metres long – to put that in context, it's bigger than the largest passenger bus. While individuals of that size are not uncommon, the average is a still-mammoth 12 metres long. The shark's mouth is a gigantic portal, which can be up to 1.5 metres in width and is positioned at the very front of its head. The head itself is flat and wide, with a rounded snout and disproportionately small eyes. They have more than 300 teeth, although they appear to serve little or no purpose, as the species is a "filter feeder". The body is generally greyish-blue in colour, with the presence of highly distinct uneven blotches of yellow distributed over the back and sides. The sharks have two large dorsal fins, two pectoral fins and an upper and lower fin on the tail. Feeding There are five massive gill slits on either side of the head. The shark feeds by taking in huge amounts of water and plankton through its mouth at high speed, then effectively sieving it through its gills – hence the term "filter feeder". The sieve system is made up of tough cartilage and filter pads containing tiny pores, which ensnares the plankton particles but allows the water to pass through. Behaviour The species is extremely migratory and have been recorded travelling thousands of miles each year, returning to the same place to feed and give birth. While many of the shark species of Galapagos are seen in great numbers in the waters around Darwin and Wolf Islands, curiously the vast number of Whale Sharks that congregate are pregnant females. This is the only part of the world where this happens and scientists have no concrete evidence as to why it is so. Growing the Knowledge Incredibly, there is very little research-based information on the breeding habits of the species. Until now there has only ever been one analysis of a pregnant female, which was found to be carrying over 300 pups in varying stages of growth. It's not known definitively how long the gestation period is, how often they give birth, or even where breeding takes place. Since 2011, the Galapagos Whale Shark Project (GWSP) has been working to rectify this gap in knowledge, in order to solidify conservation efforts and increase their understanding of the species. The team is using tagging and ultrasound technology to track the migration to and from the archipelago and learn more about the animal's physiology. Conservation GWSP is also doing valuable work in the conservation of this magnificent shark species of Galapagos, through education programmes and initiatives. With threats coming from illegal fishing (to satisfy the demand for their fins in the Asian market) and a decline in food sources, it's vital that the profile of this strangely beautiful ocean giant is raised, in order to secure its survival. Author Plate Marissa Ellis-Snow is a freelance nature writer with a special interest in the unique wildlife of the Galapagos Islands. Marissa chooses the expert-led itineraries organised by Naturetrek, which have brought her unforgettable sightings of the shark species of Galapagos along with a wide range of other wildlife in one of the most spectacular regions on Earth.
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