Once food has reached the sea floor, currents carry this food and organisms filter it without having to use their own energy to go and get food. Another way organisms use energy is by coming out at night and rising to feed on upper-level organisms.
Physical Science redirects here. It is not to be confused with Physics. Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a physical science, together called the physical sciences.
Physical Geography. This class, a foundation in the study of geography, studies the physical character of the earth. Students learn about climate issues, weather patterns, landforms, soils, vegetation and water usage. Laboratory work is routinely part of any physical geography course. This class is often offered in the first year of study.