A bit of bat biology

Bats belong to the Chiroptera order of mammals, which literally translates from greek as 'hand wing'. This refers to the fact that they have the same bone structure in their wrists and hands as any normal mammal, however they are miniature in comparison, and have a thin membrane (also known as patagium) of skin that extends from their smallest finger, supported by other extended digits, which fuses to their abdomen to form wings. Fun fact: they are the only mammals capable of sustained flight. The more you know, right? Around 70% of bats are insectivores, and in many tropical regions they fulfil a vital role as pollinators, as they drink nectar and eat fruit from various plant species also. The 1,240 or so bat species that live on earth (we're not counting the bats that live on the moon here) are divided into 2 sub-orders: the less specialised frugivore megabats and the highly specialised echolocating microbats. The megabats, like the flying fox, are not nearly as elegant as the microbats. They're a bit like flying rodents in my opinion, in comparison to the feats of evolutionary engineering which can be seen in the microbat sub-order. By far the most impressive ability of the microbat is it's echolocation. The bats emit a cry, with frequencies ranging from as low as 11 kHz to as high as 212 kHz, which is reflected back at the animal from surrounding objects, allowing it to gauge size and distance. Bats use echolocation primarily for hunting, but again there are 2 different kinds; the frequency modulated (FM) sweep, which is a downward sweep through a range of frequencies, and constant frequency (CF) signal, which is a narrowband signal over one frequency. Both techniques have hunting applications, the FM signal is used for determining the distance between the bat and target prey for example, whereas the CF signal is used to calculate the velocity of prey. You can see why echolocation is so vital for insectivorous microbats (if you can't you have seriously missed my point here). Furthermore, there are specific situations in which bats must quickly adapt and change signal. An FM component in the cry is great when flying close to prey in an environment with many obstacles or for hunting individual moths in a swarm, but CF is used to scout out prey in an open environment, or by bats lying in wait to ambush prey. Bats have adapted their morphology to better suit echolocation, by having larger ears for example so more ultrasonic sound waves can be processed or by developing a basilar membrane within the cochlea of the ear, so the bat can tune their ears for narrow frequencies reflected from flying insect prey.

Anyway, that was my attempt at doing a halloween related post... with a biological twist.