#bat fact

OK so they are distributed worldwide (except Antarctica) and obviously have some pretty big adaptations around flight

right now there's some debate going on about classification because of their adaptations- mainly based around echolocation, I'll get into that a little more later on- but the old classification system was the mega bats (megachiroptera), which was only one subgroup, and the micro bats (microchiroptera). The genetics are still iffy and to this day its still a little confusing where everybody belongs but that old way has since been thrown out the window... but still likes to watch what's going on inside if you know what I mean (I don't know what I mean....)

but anyway! this was based also around their distribution so we have what are called old world mammals which are critters found mainly in Africa, Asia, and Australia but also Europe (hence the name old world) and new world which is the Americas. Mega bats were considered new world and only held one family which is no longer the case

anyway!

we don't actually know how we got bats

well we do but we dont... let me explain!

the earliest known bat fossil was a Eocene bat found in germany (I think?) from 52.5 Mya also called Icaronycteris gunnelli and it was pretty much already a bat here's a picture

so... we don't know what it looked like before it looked like a bat! we hypothesize that it was another shrew-like mammal that just transitioned to flying really quickly. after all- that's a big commitment if you want to catch flying prey!

flying also takes up a lot of energy so they have to be tiny (except for flying foxes but I'll talk about them later) they lose heat/energy really fast so that means they need to eat a lot of high value food this leads to nearly all bats being insectovores with a few notable outliers

remember bats are super diverse there's specialization in every way you can think! the only things they won't eat are leafy greens- even the herbivores require high sugar diets and they are too small to have specialized stomachs like other plant adapted mammals.

because these guys require high energy food they also love to stay in tropical climates which is where they are the most diverse- you'll find a whole lot of bats in South Asia and South America.

so let's talk about bats as a whole now that we have some background.

Chiroptera- (literally means: hand wing)

so bat wings. they are more maneuverable than a birds wing and will encase the whole arm and in-between the fingers. they have a super duper adjustable membrane that they can move around in really subtle ways to help them navigate in the dark. their radius/ulna bones (forarm bones) are somewhat fused together and their 1st and 2nd finger acts as that final support beam for the rest of their fingers. they also have a thumb with a claw that sticks out.

their torsos are also adjusted for flight they have a super broad chest with small hips and straight long legs. their claws are independent (not fused like their wings) and they sometimes have a spur off of their ankles to help support the membrane between their legs

some of them have tails some of them do not- when they do have tails the membrane will also be connected to that at the middle.

their shoulder girdle is also special they have a long clavicle a large/strong scalpula and a ridged sternum which makes their center of gravity over their shoulders- this is really important for momma bats! they can only have one young (pup) at a time and they must stay up pretty high on her chest when drinking milk so that she can still fly. that means her nipples are real high up too (eventually she will leave the kid behind and go hunt on her own to bring back food)

here's a few modern bat skeletons

(note the ankle spur on the left image)

ft. my phone in the glass reflection... my bad dog

and check out those Itty bitty hips! imagine how small those babies have to be at birth to fit through that! haha just kidding you don't have to imagine here's a baby bat

SO small (this is a species called Myotis lucifugus the common name is literally "little brown bat")

OK so flight-

I don't know much about aerodynamics so this is gonna be like a weird bullshit explanation on this

so bats have curved wings for lift and they get thrust from their muscles on their body- they can adjust the curvature of their wings which is called the camber (if I remember correctly idfk honestly) and the front edge of their wing will change their angle of attack. they also adjust their fingers for the same deal bpa bla bla you get the point they can move their wings like crazy

so a high camble or angle of attack means a higher lift. they have super tiny thin muscles under their wing membrane that will also adjust its kinda like when horses twitch their skin to get a fly off.

wing beat cycle- upbeat brings the wing in and downbeat spreads the wing. they get their main power from their chest during the up beat and have less power from their back muscles on the down beat

a lot of them also have like a locking mechanism in their shoulder that keeps their wings from like snapping back open from the wind resistance

variability in wing size is also crazy- so long thin wings = longer flight

their tails are also like rudders and help with lift free tail bats struggle with this especially and will roost super high up and just kinda fall into flight

heavy prey like fruit requires heavy lift and that means their uroptagium (membrane between the legs) needs to be specialized for their habits

some bats use their membrane as like a net to catch moths and other flying bugs and throw them to their mouths very few bats will actually pluck things from the sky with their mouth they use their hind legs 99% of the time

(bat wing anatomy)

notice those tail variations

ears.

ears on a bat are fucking crazy there's all kinds of different variations (there's that word again) but one main trait is an extended tragus which is used to deflect sound here's a picture of a few examples

aww Lil cuties

they also have a nose leaf which we think also deflects sound (or heat in some species) both are necessary for echolocation here's some nose leafs

so while we are up here at a bats head we can talk about their skulls for a second and I'll get back to echolocation in a second

so bat skulls are similar to dogs but they may have modifications in their nasal areas and their incisors and premaxilla specifically. this again.... is super diverse and hard to kinda group together but here's a few examples

they all generally have primative molars which is called dilambodont molars its kinda a W shape with their crests but some have some crazy teeth like vampire bats some may not have any front teeth at all! they might use their hard pallet as a grinding surface like echidnas do

again... please don't ask me about teeth this is really all I know they stress me out

their relative size is also crazy variable flying foxes are the largest and can have 4-5ft wingspans and be around 2kg while bumblebee bats stay around 2g some of those larger guys can hibernate and a couple of super social ones do too

so!! elephant in the room- echolocation.

this special feat requires good ears and a good larynx

sound is produced in the larynx and comes out the mouth or though the nasal cavities this is just anatomy but in bats their nose leaf will also direct high frequencies away from themselves

remember a high frequency means a short wave length so to detect distances they need two mobile ears on their head to figure out the direction of the sounds. these move and listen somewhat independently from each other

bats are also creative with their echolocation they use a lower call when flying around to make sure they don't run into anything and a higher and faster call when they have located prey- think of it like a sonar on a submarine. the lower call sweeps the area for something to bounce back against and when something moves around like a pretty little moth for example, they will hone in on that sound to make sure they hit their target. and as we remember, high frequency requires a shorter distance from their target.

now I want to break some misconceptions real quick- no bat is blind. some bats have very small eyes and they likely don't rely on their vision but they can all see! bats are also loud! not in frequencies we can hear them but they are basically shouting all night long. echolocation also doesn't present a map of the land like some cartoons may show- again, imagine a sonar from a submarine its pretty similar but we don't actually fully understand how it's processed in their brains- we aren't bats after all!

this echolocation thing is super precise they, can tell the shape, speed, texture, size, type, orientation, and distance of something from a single call and they can go up to 200KHz

hearing the bounced back auditory waves requires a specialized auditory bullae which is shown in this photo circled in red

so these suckers are not fully attached to the skull and are instead supported by muscles so that they won't deafen themselves with their own yelling. they will relax that muscle when yelling and retract it to listen

this is so precise that they can identify and avoid a .2mm wide wire from a full meter away and can detect a fruit fly from 1/3rd of a meter away

if a bat had their way they could catch prey every 7 seconds (and catch a fruit fly every 3 seconds)

alright I'm gonna leave it here as my overview on bats and next time I'll get into some specific species and the differences between yin and yang bats :)

I hope this post was interesting to you and I hope you learned something! please feel free to ask me anything else thank you for your question!

I've also maxed out on both images AND tags for this post so I'm likely going to try and split up these bigger posts more often

OH before I forget (and I'll do a post on bat conservation too) just a firm reminder DO. NOT. TOUCH. BATS.

they are cute! they are excellent bug catchers! we love them! BUT they are also carriers of lots of diseases that humans can get such as rabies, ebola, and yes covid-19 not only that they are also ILLEGAL to touch

if you see a hurt bat or if one gets stuck in your garage or something call animal control they will send out a LICENSED Profesional to handle it for you

here's some information on the federal laws surrounding bats but always check your state laws as well!

DO.

NOT.

TOUCH.

BATS.