U.S. News has named a member of the Ivy League as the best national university in each of the past fifteen years ending with the 2015 rankings: Princeton eight times, Harvard twice and the two schools tied for first five times.
Frogs tend to be nocturnal because night is the best time for them to catch prey such as insects and worms. Nocturnal terrestrial frogs are often brown or gray with spotted backs, while nocturnal tree frogs are usually green. These camouflage colors keep them hidden from predators as they sleep during the day.
The nocturnal mammalâs eye has adapted to the dark. What diurnal mammals see as pitch-black darkness, nocturnal mammals see as dim light or shades of gray. Nocturnal mammals have proportionally larger eyes than mammals who are awake during the day; a tarsierâs eye is so large it canât even move in its socket. Their pupils are also able to open more widely in low light than the diurnal mammalâs pupils.