the terrestrial animals, or amphibious animals, breathe by lungs.they intake oxygen from air through nose and the respiration took place in lungs like us humans ;-)
animals usually depend on plants for oxygen. we breath out carbon dioxide and breath oxygen in, same with animals. and plants breath that carbon dioxide in and and breath out oxygen.
their breath
it makes it hard for the animals to breath
oxygen
we and the animals breath it.
Through their lungs
You but them in a spacecraft with oxygen in it
to breath stupid ^Darn, beat me to it
because animal breath
yes, all insects breath oxygen in and carbon dioxide out (as do all animals)
Plants create oxygen for the animals to breath, and the animals turn that into carbin dioxide, so that the plants can breath that in, and give the animals more oxygen. This cycle goes on around everywhere, including humans.
Plants breath in the CO2 we breath out and then turns it into O2 for us to breath in again, mutually beneficial.