Leatherback sea turtle and large size, leatherbacks are able to maintain high temperature differentials compared to the surrounding water. Adult leatherbacks have been found with core body temperatures that were above the water in which they were swimming. Leatherback turtles are one of the deepest-diving marine animals. Individuals have been recorded diving to depths as great as . Typical dive durations are between 3 and 8 minutes, with dives of 30–70 minutes occurring infrequently. They are also the fastest-moving reptiles. The 1992 edition of the "Guinness Book of World Records" lists the leatherback turtle moving at in the water. More typically, they swim
History of manifolds and varieties History of manifolds and varieties The study of manifolds combines many important areas of mathematics: it generalizes concepts such as curves and surfaces as well as ideas from linear algebra and topology. Certain special classes of manifolds also have additional algebraic structure; they may behave like groups, for instance. In that case, they are called Lie Groups. Alternatively, they may be described by polynomial equations, in which case they are called algebraic varieties, and if they additionally carry a group structure, they are called algebraic groups. The term "manifold" comes from German "Mannigfaltigkeit," by Riemann. In English, "manifold" refers to