Microbats are defined as bats who primarily use echolocation for navigation and finding food. All bats are in the order Chiroptera. ‘Chiro’ (like chiropractor) means ‘hand’, ‘ptera’ (like pterodactyl) means ‘wing’. The wing of a bat is very similar to our hand (and arm) in bone structure but with elongated metacarpals.

Micro-chiroptera and Mega-chiroptera = Microbats and Megabats

There are two different classifications for bats. In the first, bats can be divided into two groups, based on morphology and behaviour. These groups are Microchiroptera (microbats) and Megachiroptera (megabats) and echolocation is the crucial difference between them. Some microbats are larger than some megabats so size is not always a reliable difference. All microbats rest with the wings folded along their forearms. Megabats do this too but often have their wings wrapped across their bodies. Megabats all eat fruit and/or nectar, but some also occasionally eat insects. Most microbats eat insects, but some also eat fruit and nectar. Some microbats of course are also carnivorous, or eat fish, spiders or blood. It is difficult to find any absolute difference between the two groups other than echolocation. Even then, there is a megabat, the Egyptian fruit bat Rousettus egyptiacus that uses a type of echolocation within its cave roosts. It does this by clicking its tongue, not the larynx echolocation method of microbats, where air passes over the vocal cords.

Yinptero-chiroptera and Yango-chiroptera

In the second classification, bats are also divided into two groups but based on morphological, molecular (genetic) and fossil evidence. This evidence shows that all the leaf-nosed microbats have more in common with the megabats and so they are in Yinptero-chiroptera. The rest of the microbats and by far the most, are in Yango-chiropteraThink of the ‘Yin’ group as the leaf-nosed microbats and the ‘Yang’ group as the rest of the microbats, as in the previous classification system. The ‘Ptero’ group represent the megabats from the first classification system.

Illustration of the upper limbs of humans, birds and bats.
illustration of the classification system of bats

The two bat classification systems,
illustration taken from Current Biology and Batsrule website.

Illustration (left) comparing the human, bird and bat upper limb

Blind as a bat?

All bats have eyes and use their eyes to a greater or lesser extent. Some like the Diadem leaf-nosed bats (Hipposideros diadema) with very small eyes may only use their eyes to know if it’s day or night. Others like the Ghost bat (Macroderms gigas) have very large eyes and use them a lot, especially when in a stealth mode hunting insects that can hear their echolocation calls. They choose then not to use their echolocation, and use their hearing and vision.

Photo (right): Ghost bat with large eyes and large nose-leaf.

What is a nose-leaf?

“Nose-leaves are folds of skin and cartilage of varying complexity which may extend over a large part of the microbat’s face. In many species the nose-leaf appears to act as an acoustic lens, focussing the sound into a narrow beam in front of the bat”. Bats: Biology and Behaviour. John D. Altringham 1998. The effect may be the same as cupping your hands around your mouth to direct and project your voice. Most microbats echolocate from the mouth, but those with a nose-leaf echolocate from the nose. It is thought the structure resembles a leaf.

Echolocation

Echolocation is a complex and highly evolved process where the bat analyses the echoes of its sound waves to build a sound-picture of its immediate environment. It is too large a subject to do justice to it here, but there are some internet links in the text above to help you understand it.

The ghost bat has large eyes and a large nose-leaf.