How long do sharks stay in the twilight zone?
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The twilight zone, also called the Mesopelagic zone, begins at the depth where only 1% of incident light reaches (200 m/ 645 feet) and ends where there is no light (1000m/3280 feet). It is home to some of the largest fish biomass on Earth, making it a unique feeding ground for the ocean’s largest predators. Many shark species venture from surface waters to the deep ocean between 200 and 1000 meters (656 to 3280 feet) and experts believe the main purpose is to hunt for prey when food is scarce in surface waters.
Different shark species spend varying lengths of time in the twilight zone. Blue sharks spend up to an hour hunting for a meal; whale sharks can spend a few hours; and basking sharks take it to the extreme, spending up to four months feasting on twilight zone creatures before reemerging to the sunlit surface waters.
There could be other reasons for sharks to visit the twilight zone. For example, besides feeding, whale sharks visit the twilight zone to cool down, remove parasites, save energy, or even to calibrate their internal navigation.