Dissolved oxygen concentrations are constantly affected by diffusion and aeration, photosynthesis, respiration and decomposition. While water equilibrates toward 100% air saturation, dissolved oxygen levels will also fluctuate with temperature, salinity and pressure changes ³.
Humans' and rats' incisors are larger than their other teeth, though humans' incisors are only marginally larger. They perhaps share this characteristic to help them adapt to an omnivorous diet.