Like many creatures, humpback whales migrate long distances for feeding and mating purposes. How animals manage to migrate long distances is often puzzling. In the case of humpback whales, we may have found the answer: they may be navigating by the stars, much as early human sailors did. What we know about humpback whales makes this a distinct possibility.
First, humpback whales seem to be intelligent enough to use stars to navigate by. Whales' brains have a high degree of complexity--a common determiner of intelligence. This suggests that the whales' brain power far exceeds that of most other animals. The whales' well-developed cognitive ability seems to provide a sound basis for the ability to use a complex, abstract system of sensory stimuli such as the night sky for orientation.
Second, humpback whales migrate in straight lines. Animals can maintain movement in a straight direction for long distances only if they orient themselves by some external objects or forces. Many birds and other terrestrial creatures, for example, use physical landmarks to help them stay on track as they migrate. Whales, which swim in the open ocean, cannot rely on land features; they could, however, rely on stars at night to provide them with external signs by which to maintain direction over long distances.
Third, humpback whales exhibit an unusual behavior: they are sometimes observed floating straight up for minutes at a time, their heads above the water as though they were looking upward. The behavior is known as spy-hopping, and it is very rare among marine animals. One explanation for the function of spy-hopping is that the whales are looking at the stars, which are providing them with information to navigate by.
vt. 欣赏；感激；领会；鉴别 （appreciate的第三人称单数）
They don't have any confidence that houses will appreciate in value.(TPO49-20)