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在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 A Warm-Blooded Turtle
When it comes to physiology, the leatherback turtle is, in some ways, more like a reptilian whale than a turtle. It swims farther into the cold of the northern and southern oceans than any other sea turtle, and it deals with the chilly waters in a way unique among reptiles.
A warmblooded turtle may seem to be a contradiction in terms. Nonetheless, an adult leatherback can maintain a body tem perature of between 25 and 26°C (77 79°F) in seawaterthat is only 8 °C (46.4° F). Accomplishing this feat requires adaptations both to generate heat in the turtle' s body and to keep it from escaping into the surrounding waters. Leatherbacks apparently do not generate internal heat the way we do, or the way birds do, as a byproduct of cellular metabolism. A leatherback may be able to pick up some body heat by basking at the surface; its dark, almost black body color may help it to absorb solar radiation. However, most of its internal heat comes from the action of its muscles.
Leatherbacks keep their body heat in three different ways. The first, and simplest, is size. The bigger the animal is, the lower as surface tovolum e ratio; for every ounce of body mass, there is proportionately less surface through which heat can escape. An adult leatherback is twice the size of the biggest cheloniid sea turtles 409
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and will therefore take longer to cool off. Maintaining a high body temperature through sheer bulk is called gigantotherrny. It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. It apparently works, in a smaller way, for some other sea turtles. Large loggerhead and green turtles can maintain their body temperature at a degree or two ab...
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This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.
- Fall '13