The Importance of Oxygen in Animals
Oxygen is an element crucial to the survival of all animals, because it creates adenosine triphosphate, or ATP, an organic compound that when broken down releases energy. When oxygen and glucose are taken into the organism, they form ATP in the mitochondria. This is called cellular respiration, and other than ATP, water and carbon dioxide - which gets discarded as waste - are created.
In humans, the oxygen enters the body when we breathe in air via the nose or mouth. From there, it goes down the larynx to the trachea, goes through the bronchi, which are located in the lungs, into the bronchioles and then the alveoli, which are small sacs surrounded by capillaries. The oxygen diffuses out if the capillaries into carbon-dioxide filled blood. When the oxygen diffuses out, the carbon dioxide diffuses into the capillaries and exits the body as we exhale, going through the alveoli, to the bronchioles, to the bronchi, to the trachea, to the larynx, and finally out of the nose or mouth. This action of breathing in and out is caused by the muscle below your lungs called the diaphragm that when contracted pulls oxygen into the lungs, and when relaxed lets carbon dioxide out of them.
Gas Exchange in the Mantis Shrimp
Mantis Shrimp, unlike humans, get their oxygen from water instead of air. And, instead of having lungs, they obtain oxygen with gills located on the exterior of their bodies. The gills are located on the outer branches of the pleopods, which are the forked swimming limbs usually on the abdomen. These gills have this walls and are made up of lamellae, which are thin, plate-like structures. They have as large of a surface area as possible so that enough oxygen goes through when water passes over it. The oxygen diffuses through a thin membrane and enters into the bloodstream of the Mantis Shrimp. Mantis shrimp also use a respiratory pigment called hemocyanin, which is a copper-based that helps transport oxygen throughout the body