when we inhale we inspire, 
when we exhale we expire. 

zapsammy

Ok, I was thinking about their food input and output. Topologically, it sounds like they have a forked tube (presumably not the technical term) for respiration.

Undisciplined

Stacker Saloon

saloon

> Respiration involves drawing water into the mantle cavity through an aperture, passing it through the gills, and expelling it through the siphon. The ingress of water is achieved by contraction of radial muscles in the mantle wall, and flapper valves shut when strong circular muscles force the water out through the siphon

-- [Wikipedia, _Octopus_](https://en.wikipedia.org/wiki/Octopus#Respiration)

if I understand correctly, at least their input is not also their output?

> Water flow over the gills correlates with locomotion, and an octopus can propel its body when it expels water out of its siphon.

-- ibid

and that means they use breathing out to propel themselves forward, cool!

_kind of jealous rn, ngl_