The conditions of a habitat remain changing abruptly and periodically.
Abrupt changes in environment often do not give time to an organism to get ready and to face the challenges. As such the organism can survive only when it has sufficient abilities to tolerate these changes.
Periodic changes form a pattern and occur again and again at more or less fixed intervals. Under these conditions, an organism gets sufficient time to develop abilities of tolerance. Such ability is the ability of hibernation or aestivation.
Organisms have to undergo various types of structural and functional modifications that enable to adjust in a particular environment in which they live. This is called as adaptation.
Dictionary defines adaptation as- an alteration or adjustment in structure or habits, often hereditary, by which a species or individual improves its condition in relationship to its environment.
In other words, adaptation can be defined as change in behaviour of a living being or group in response to new or modified surroundings.
Adaptations can be anatomical, behavioural or physiological. Anatomical adaptations are physical features such as the shape of a plant or of an animal.
Behavioural adaptations can be inherited or learnt and include tool use, language and swarming behaviour.
Physiological adaptations include the ability to make toxin or venom; but also, more general functions such as regulation of temperature.
Adaptation to extremes of environment incorporates many special behaviours and physiological changes that living beings need to withstand the harshest conditions and environments of the earth.
Whether it’s a lack of oxygen at altitude, the searing heat of deserts or the bitter cold of the polar regions, plants, animals and other organisms have evolved a multitude of strategies that protect them.
Plants and animals develop numerous survival strategies that enable them to cope with particular stresses, from temporary environmental changes in the weather to the constant threat of predation.
So, for instance, to avoid the cold of winter animals may migrate away or hibernate, while trees may shed their leaves. To avoid predation, plants may be poisonous or covered with defensive spikes and animals may use camouflage or travel in great numbers.
Here are some examples of adaptations-
Many amphibians go on hibernation during winters to protect themselves from cold because they are cold blooded that is the temperature of their blood changes with the changing atmospheric temperature.
Hibernation is an extended period of deep sleep that allows animals to survive winter extremes. These animals cannot survive the extremes of summer as well and to protect themselves from the rising temperature during summers they go deep underground in cold places. This strategy is called as aestivation.
Many animals have tendencies of food storage. Rabbits, squirrels, rats and even ants store food for bad days.
Food storage is a strategy for getting through hard times when resources remain low because of seasonal and other factors. Many carnivores such as foxes and leopards bury surplus prey and return to eat a few days later. Squirrels bury enough nuts to get them through the winter.
Many birds and fish migrate to other habitats during unfavourable conditions of the environment. Migration is usually seasonal movement of animals in pursuit of food, suitable breeding sites or to escape bad weather conditions.
Mass migrations such as wild beasts crossing certain river, or migration of pacific salmon towards up stream to mate are strange adaptations.
Defence against predation is another form of adaptation that is observed in many cases. The predation defence is seen in many forms such as physiological, anatomical and behavioural.
Spines and thorns on plants are physical adaptations. Avoiding detection through camouflage and mimicry; chemical defence by way of secretion of toxin or poison or the exudation of irritants, to repel enemies are strange examples of adaptations.