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.
Poison dart frogs are sometimes called poison arrow frogs or dart poison frogs or poison frogs. All of these names refer to the fact that these frogs secrete poisons.The poison from poison dart frogs is used by Central and South American Indians on the darts they use for killing animals.oison dart frogs are sometimes called poison arrow frogs or dart poison frogs or poison frogs. All of these names refer to the fact that these frogs secrete poisons.