Carbon dioxide and water vapor.
The active gas in air is HYDROGEN. i learnt this learning my chemistry.
by dying or breathing
Breathing
Oxygen is required for breathing also you might want nitrogen too
Animals take in oxygen and release carbon dioxide.
if animals sweat,w\they evaporates and condenses into water droplets
Animals and insects form a part of the carbon cycle, eating and breathing, and then releasing the carbon as gas and waste.
Carbon Dioxide.
carbon dioxide
animals and plants release carbon dioxide from respiration plants alone release oxygen from photosynthesis
it can give out a very toxic gas called methane
Lungs for air breathing animals Gills for water breathing animals