Leatherback sea turtle shallower water at night (when the jellyfish rise up the water column). This hunting strategy often places turtles in very frigid waters. One individual was found actively hunting in waters that had a surface temperature of 0.4 °C. (32.72 °F). Leatherback turtles are known to pursue prey deeper than 1000 m—beyond the physiological limits of all other diving tetrapods except for beaked whales and sperm whales. Their favored breeding beaches are mainland sites facing the deep water, and they seem to avoid those sites protected by coral reefs. Adult "D. coriacea" turtles subsist almost entirely on jellyfish. Due to their
Varieties of Chinese their own standard languages. In China, however, Literary Chinese maintained its monopoly on formal writing until the start of the 20th century. The logographic writing, read with varying local pronunciations, continued to serve as a source of vocabulary and idioms for the local varieties. The new national standard, Vernacular Chinese, the written counterpart of spoken Standard Chinese, is also used as a literary form by speakers of all varieties. Dialectologist Jerry Norman estimated that there are hundreds of mutually unintelligible varieties of Chinese. These varieties form a dialect continuum, in which differences in speech generally become more pronounced as distances