Naked Science Forum

General Science => Question of the Week => Topic started by: nudephil on 20/10/2020 10:58:44

Title: QotW - 20.10.19 - How do bats sleep upside down?
Post by: nudephil on 20/10/2020 10:58:44
This week's question comes from Satish:

How does a bat sleep the whole day hanging from a tree? Won't being upside down affect blood circulation?
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: evan_au on 20/10/2020 11:47:18
Most bats are pretty small, so there is very little blood pressure difference between the top and bottom of their bodies.

Humans are much larger, and have mechanisms to ensure that blood circulates well in 1g gravity. Take away the gravity (eg in the ISS), and humans suffer from a swollen head, nasal congestion and other unpleasant side-effects.

Even more extreme is the giraffe.  There are severe blood pressure changes between nibbling leaves on a tree-top and nibbling grass on the ground. There are valves in its neck to prevent it fainting when it reaches up, or suffering a stroke when it drinks water...

See: https://www.breakthroughs.com/foundations-science/what-we-can-learn-giraffe%E2%80%99s-neck
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: Bored chemist on 20/10/2020 12:36:27
They are not upside down.
Hanging by the feet is the right way up- for a bat.
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: evan_au on 20/10/2020 21:52:15
Quote from: OP
Won't being upside down affect blood circulation?
Being upside-down certainly affects excretion.

Bats poop while in flight...
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: Colin2B on 20/10/2020 22:04:02
Quote from: OP
Won't being upside down affect blood circulation?
Being upside-down certainly affects excretion.

Bats poop while in flight...
They also do it in their roost. Looks a lot like mouse droppings.
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: chris on 21/10/2020 15:12:41
How do bats sleep upside down?

...if they've had a bout of diarrhoea, nervously...
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: evan_au on 21/10/2020 20:44:33
Quote from: Colin2B
Looks a lot like mouse droppings.
One of the suggestions about the origin of SARS-CoV2 is that farmers go into nearby bat caves to collect the bat guano to use as a fertilizer.

These people are likely to pick up bat viruses. When investigating the origins of SARS, bats were found with a similar virus, and some people in the community were found to have antibodies against these viruses.

Presumably, the original infection was not very infectious between humans, and so a few local people who entered the caves caught the disease, but it didn't go on to cause a pandemic.

And then a mutation happened that made it much more infectious/transmissible ....
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: nudephil on 02/11/2020 18:23:17
Answered: https://www.thenakedscientists.com/podcasts/question-week/how-do-bats-roost-upside-down
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: Scientist30 on 07/11/2020 17:51:03
But what about the bats that are a lot larger? The blood pressure difference would certainly be a lot higher.
Title: Re: QotW - 20.10.19 - How do bats sleep upside down?
Post by: strongernow on 10/11/2020 17:13:33
Most bats are pretty small, so there is very little blood pressure difference between the top and bottom of their bodies.

Humans are much larger, and have mechanisms to ensure that blood circulates well in 1g gravity. Take away the gravity (eg in the ISS), and humans suffer from a swollen head, nasal congestion and other unpleasant side-effects.

Even more extreme is the giraffe.  There are severe blood pressure changes between nibbling leaves on a tree-top and nibbling grass on the ground. There are valves in its neck to prevent it fainting when it reaches up, or suffering a stroke when it drinks water...

See: https://www.breakthroughs.com/foundations-science/what-we-can-learn-giraffe%E2%80%99s-neck

Sounds logic to me. Is it maybe as well as a strategy to be save while sleeping or how made evolution do bats sleep upsidedown?