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
Echolocation jamming times fainter than the sounds they emit. To avoid deafening themselves, whenever a bat makes an echolocation emission, a small muscle in the bat's middle ear (the stapedius muscle) clamps down on small bones called ossicles, which normally amplify sounds between the ear drum and the cochlea. This dampens the intensity of the sounds that the bat hears during this time, preserving hearing sensitivity to target echoes. Jamming can occur if an animal is still producing a sound when an echo returns, for example, from a nearby object. Bats avoid this type of jamming by producing short sounds of 3-50