How temperature affects the animals

It affects the kinetics of enzymes, like Growth and Development, Reproduction, Thermal tolerance, Metabolism, Thermal regulation & Some other factors are also there.

Now, how temperature affects all of these

How temperature affects growth and development: we can take example of Ostrea, In Ostrea, the length of body increases from 1.5 to 10.3 mm with an increase in temperature from 10° to 20 °C.

How temperature affects Reproduction: In animals, the maturation of gonads and activity of spermatogenic tissue are also temperature dependent, which varies from species to species. In blow fly, Calliphora sericate, the number of eggs laid per female, increases with increase in temperature upto 32.5 °C. Thus, temperature also affects the fecundity (reproductive capacity) of animals. Some animals lay “winter eggs” after which adults die while the eggs are resistant to low temperature.

How temperature affects Thermal tolerance. On the basis, of Thermal tolerance animals can be divided into five categories

  • Eurythermal organisms: These can tolerate a wide range of temperature fluctuations e.g. Cyclops, toad, wall lizard, man, cows, dogs and Zostera angiosperm. etc.
  • Stenothermal organisms: These can tolerate only a small range of temperature variation e.g. corals, polar bear, snails and fishes; and Mango plant and palm.
  • Mesothermal organisms: Organisms living at high summer temperature and low winter temperature.
  • Microthermal: Organisms living at high temperatures.

How temperature affects Metabolism: Temperature fluctuations have a remarkable effect on metabolism mainly due to acceleration of enzymes-controlled chemical reactions.

How temperature affects Thermal regulation: Different living organisms tide over very low or very high temperature conditions differently e.g.

  • Encystment: It involves the formation of a hard and chitinous protective coat, called cyst, around the body. It is commonly seen in Amoeba, Euglena and many invertebrates. Encysted capsules are also formed in the life cycle of flukes, tapeworms and nematodes.
  • Periodic activity: Snakes are generally nocturnal. Calotes, Crocodylus, Testudo, etc. warm up their body by basking in the sun during day.
  • Cyclomorphosis: It is characterized by change in body shape with seasonal temperature change and has been observed in small aquatic organisms like Cladocera, Daphnia, etc. In Daphnia, the size of helmet on head increases with increase in temperature of environment.
  • Thermal migration: It involves the shorter or longer journeys undertaken by animals so as to resist the temperature extremes e.g. nocturnal activity of some of desert animals; and long-trip migration by many birds (e.g. Arctic tern, Siberian cranes, American golden plover etc.), mammals (e.g. Bison, Reindeer Caribou etc.) and fishes (e.g. Aguilla, Salmon etc.)
  • Thermoregulation and homeostasis: The birds and mammals have constant body temperature and are called homeothermal or endothermic or warm blooded animals to deal with temperature extremes. This is achieved through evaporation of water from their bodies during summer and through insulating action of fur, feathers, fats etc. during cold weather of winter months; conservation of body heat by a layer of paniculus adiposus of subcutaneus zone especially in whales, seals, polar bear and elephants erection of hair by arrector pili muscles to trap more air and constriction of superficial blood vessels. During winter months, the human beings and other mammals shiver which increases muscular activity, produces heat and raises the body temperature. Process of metabolic heat production in response to cold environment is called thermogenesis.
  • Behaviour: Temperature changes also induce certain behavioural patterns e.g. rattle snake, vipers etc. can detect their prey by their body heat.

Some other factors are Variations and Sex ratio.

Variations: Altenberg and Muller showed that increase in temperature increases the chances of crossing over in Drosophila melanogaster (fruit fly).

Sex ratio: In some animals, sex ratio is affected by temperature e.g. in Macrocyclops, there is increase in number of males with increase in temperature, while in Xenopsylla cheopsis a mean temperature of 21-25 °C favours females.

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