Bat Echolocation Notes

Echolocation in bats Classification of bats Bats are mammals or the order chiroptera of which there are two suborders 1. megachiroptera 150 species which are vegetarian, large fruit bats, wingspan up to two metres, they have very big eyes adapted to night vision and have small ears. no echolocation 2. microchiroptera around 800 species, very small bats, smaller than 15 cm potentially. Very tiny eyes not used, and have massive ears because they echolocate. Generally insectivores like moths, mosquitos, but some can eat small fish and mammals. A few species eat blood. Bats are nocturnal and hunt at dark. Discovery of echolocation Discovered in 1800 by Lazarro Spallanzani, and he discovered that if you blindfold bats, and let them fly, they were still able to navigate. He tried to plug their ears and he noticed that they lost the ability to navigate. However, echolocation not discovered yet, as they use ultrasound, which were not discovered until the 20th century when Donald Griffin made an oscilloscope. Griffin continued with the experiments, he taped the mouth of the bats shut and they also lost the ability to navigate. So bats emit sounds from their mouth, bounces off objects and this is detected by the ears. This is called echolocation: the production of sound by animals and the subsequent determination of the position of objects from information encoded in acoustic reflections. Dolphins use an adapted method for water navigation. Sound characteristics Sound is a pressure wave, and al waves have three main characteristics: 1. Period time between two peaks 2. Frequency the reciprocal of period. Number of peaks in a given time. Also called pitch 3. Amplitude the loudness of the sound (the height of the peak) Sound can be three different types. Humans can hear from 20Hz to 20,000Hz. Less than audible range is called infrasound (rats) and above that is ultrasoune (bats). 

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