Bat prevent them from spending too much time in unfamiliar places, and decrease predation. In some species, pregnant individuals may not use torpor. The smallest bat is Kitti's hog-nosed bat ("Craseonycteris thonglongyai"), which is long with a wingspan and weighs . It is also arguably the smallest extant species of mammal, next to the Etruscan shrew. The largest bats are a few species of "Pteropus" megabats and the giant golden-crowned flying fox, ("Acerodon jubatus"), which can weigh with a wingspan of . Larger bats tend to use lower frequencies and smaller bats higher for echolocation; high-frequency echolocation is better at detecting
Evolutionary arms race best survival rate. Bats have evolved to use echolocation to detect and catch their prey. Moths have in turn evolved to detect the echolocation calls of hunting bats, and evoke evasive flight maneuvers, or reply with their own ultrasonic clicks to confuse the bat's echolocation. The Arctiidae subfamily of Noctuid moths uniquely respond to bat echolocation in three prevailing hypotheses: startle, sonar jamming, and acoustic aposematic defense. All these differences depend on specific environmental settings and the type of echolocation call; however, these hypotheses are not mutually exclusive and can be used by the same moth for defense. The different