Temperature

Temperature

The degree of hotness or coldness of a body is called temperature. Temperature is one of the most essential and changeable environmental factors which influence all forms of life. Temperature influences the viral activities of organisms such as metabolism, reproduction, growth and development, behaviour and death. The environmental temperature fluctuates both daily and seasonally and also from place to place. The temperature fluctuates are comparatively less in the aquatic environment than the terrestrial environment due to the high specific heat capacity of water.

The deep lake shows different thermal stratifications. It has three strata:

• Epilimnion: Temperature up to 22ºC in summer.
• Metalimnion or Thermocline: Temperature between 3 to 9°C.
• Hypolimnion: Temperature close to 4°C.

The normal life process of organism goes on smoothly at a specific temperature or at the specific range of temperature called optimum temperature or optimum range of temperature. The enzymes show its highest activity in optimum temperature. It varies among organisms. However, the life in this universe can exist in the range of -200 to +100°C but the normal life can persist with a narrow range of temperature of about -10°C to 50°C.

On the basis of the temperature tolerance capacity, organisms are of two types:

Eurythermal organisms:

The organisms which can tolerate a wide range of temperature are called eurythermal organisms. Eg: frog, toad, the wall lizard, grass snake, man etc.

Stenothermal organisms:

The organisms which can tolerate a narrow range of temperature are called stenothermal organisms. Eg:fishes, snails etc.

Adaptation of organisms in response to temperature

Encystment:

Formation of a hard chitinous protective layer around the body called cyst.

Aestivation (summer sleep): It is the similar condition in which other species pass periods of heat or drought in warm latitudes. For example;Snails achieve a state of dormancy during the summer in tree trunks, under leaves or on stone walls.

Hibernation (winter sleep):State of inactivity and metabolic depression in endotherms is know as hibernation.An inactive state resembling deep sleep in which certain animals living in cold climates pass the winter is called hibernation. For example;Several mammals hibernate during the long, cold winters. Woodchucks are one example of true hibernators. During their hibernation, the woodchuck's heart goes from 80 beats per minute to only four or five. It also drops its body temperature to 60 degrees below normal.

Homeothermy:

The ability of organisms to maintain the body temperature constant is known as homeothermy.

Thermal migration:

Excessive low or high temperature compel the animals to migrate from one place to another.

Development of thick bark, dense hairy coat, thick leaves, thick cubical mucilage etc. in plants to protect from extreme temperatures.

Influence/Effects of temperature on organisms

• The rate of metabolism is influenced by temperature as the enzymatic actions occur in the organisms are temperature dependent. The enzymes show its highest activity at the optimum temperature and become inactive in high and temperature.
• The rate of perspiration in animals is also controlled by temperature. The excessive high and low temperature compel the animals to migrate from one place to another called thermal migration.
• The maturation of gonads and gametogenesis in different animals are also temperature dependent.
• In certain animals, the sex ratio is determined by temperature.
• Temperature influence on the speed and success of development and growth of eggs and larva of animals.
• Temperature generally influences the behavioural pattern of animals.
• The rate of transpiration is affected by temperature. Higher the temperature, higher is the transpiration rate.
• Soil temperature also plays an important role in seed germination.
• The very low and high both temperature retard the growth and development of plants. The high temperature causes heat injury whereas low temperature causes freezing injury.