Modified: 2020-03-18
Light--a small portion of electromagnetic radiation. Light has wave properties but also can be thought of as particles (photons). The eye evolved to detect light. It converts light into neural activity.
Sound--pressure waves in a medium. Media can be solids, liquids, or gases. However, if there is no medium, there is no sound. The ear evolved to detect sound. It converts sound into neural activity.
Dissolved chemicals--Chemicals dissolve in our saliva. The taste buds on the tongue evolved to detect chemicals dissolved in saliva.
Volatile chemicals--Chemicals that exist in gaseous form. The olfactory apparatus in the nose evolved to detect volatile chemicals.
Mechanical stimuli--Stimuli that involve movement or pressure. The cutaneous or skin senses evolved to detect pressure, pain, hot, and cold stimuli on the skin.
Gravity and acceleration--Stimuli from the mass of the earth, or stimuli created by changes in velocity. The vestibular and kinesthetic senses evolved to detect gravity and acceleration, and body position respectively.
Some physical forces are not detected by any organs of our body. Examples include magnetic fields, electric fields, and echolocation. We have created instruments that can detect these forces, but we cannot detect them with our bodies alone. Some animals, however, do have organs that can detect these forces.
- Night Vision
- Interactive site from NOVA program, Leopards, discusses night vision and allows users to interact with eight animal eyes. http://www.pbs.org/wgbh/nova/leopards/nightvisionsans.html