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Great White Adaptations
zaheer2alvi - 9/17/2007 8:25 PM
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Category: Educational
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Great white sharks, like all other sharks, have an extra sense given by the Ampullae of Lorenzini, which enables them to detect the electromagnetic field emitted by the movement of living animals. Every time a living creature moves it generates an electrical field and great whites are so sensitive they can detect half a billionth of a volt. Most fish have a less developed but similar ability in the horizontal line along their body. To more successfully hunt fast moving and agile prey such as sea lions, the poikilothermic great white shark has developed adaptations that allow it to maintain a body temperature warmer than the surrounding water. One of these adaptations is a "rete mirabile" (Latin for "wonderful net"). This close web-like structure of veins and arteries, located along each lateral side of the shark, conserves heat by warming the cooler arterial blood with the venous blood that has been warmed by the working muscles. This keeps certain parts of the body (particularly their brain) at temperatures up to 14°C above the surrounding water, while the heart and gills remain at sea-temperature. When conserving energy (a great white shark can go weeks between meals), the core body temperature can drop to match the surroundings. A great white shark`s success in raising its core temperature is an example of gigantothermy. Therefore, the great white shark can be considered an endothermic poikilotherm, because its body temperature is not constant but is internally regulated.