The normally available Thermometers in the market are calibrated in either degrees Fahrenheit (°F) or degrees Celsius (°C)
depending on the country where it is being sold. United States follows Fahrenheit measurement
whereas most other countries follow degrees Celsius.
Mammals including human beings are able to maintain a constant body temperature irrespective of the
temperature of the environment, whereas in reptiles and fishes the body temperature changes as per the environment temperature.