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The following points highlight the top nine strategies of adaptation in animals. The strategies are: 1. Migration 2. Hibernation 3. Aestivation 4. Camouflage 5. Mimicry 6. Echolocation 7. Warning Colouration 8. Water Scarcity 9. Cold.
Strategy # 1. Migration:
This is a seasonal movement of complete population of animals to a more favourable environment. It is usually a response to lower temperatures resulting in a reduced food supply. Migration is common in mammals (e.g., porpoises), fish (e.g., eels and salmon) and in some insects but is most marked in birds.
The Arctic tern, for example, migrates annually from its freeding ground in the Arctic region to the Antaractic, a distance of some 17, 600 km. In Africa, wild beasts migrate long distances, following a geographical pattern of seasonal rainfall and availability of fresh vegetation.
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On the other land, thousands of locusts migrate in search of new feeding grounds from the food depleted areas, in the arid regions.
Strategy # 2. Hibernation:
This is a sleeplike state in which some animals pass the winter months as a way of surviving food scarcity and cold weather. Various physiological changes occur, such as lowering the body temperature and slowing of the pulse rate and other vital processes, and the animal lives on its reserve of body fat.
Animals that hibernate libermate include bats, northern ground squirrels hedgehogs, and many fish, amphibians and reptiles.
Strategy # 3. Aestivation:
A state of inactivity occurring in some animals, notably lungfish and ground squirrels in south-west deserts, during prolonged periods of drought or heat. Feeding, respiration, movement, and other bodily activities are considerable slowed down. The ground squirels, avoid heat by spending dry-hot period in a torpid state in burrows.
Strategy # 4. Camouflage:
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Also known as cryptic appearance; in some animals, the capacity to blend with surrounding is a common adaptation. Some insects, reptiles and mammals have markings on their bodies, which make it difficult to distinguish them from shadow and branches.
For example, a grasshopper (Arantia rectifolia), looks like a complete leaf or a part of leaf, while praying mantis (Phyllocrania paradoxa) resembles a dead leaf, thus they protect themselves from the enemies by much behavioural strategies of adaptations.
Strategy # 5. Mimicry:
The resemblance of one animal to another which has evolved as a means of protection. Here, one species called the mimic is palatable to its predators, but resembles another species, called the model, which is distasteful to the predator.
There are two types of minicry:
(i) Batesian minicry and
(ii) Mullerain mimicry.
(i) Batesian Mimicry:
In this form of mimicry the markings of certain harmless insects closely resemble the warning colouration of another insect (the model). Predators that have learnt to avoid the model will also avoid good minics of it.
This phenomenon is often found among butterflies. For examples, monarch butterfly and the mimics vicerory butterfly. Here, monarch butterfly contains toxins in its body and mimicked by vicreroy butterfly which has no toxins.
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(ii) Mulierian Mimicry:
This form of mimicry involves the mutual resemblance of a group of animals, all harmful, such as the wasp, bee and hornet, so that predator, having experienced one will subsequently avoid all of them. The other examples are-monoarch butterfly and the mimic queen butterfly. Here the mimic shares the same defensive mechanisms as the model.
Strategy # 6. Echolocation:
A method used by some animals (such as bats, dolphins and certain birds) to detect objects in the dark. The animal emits a series of high-pitched sounds that echo back from the object and are detected by the ear or some other sensory receptor. From the direction of the echo and from the time between emission and reception of the sounds the object is located, often very accurately.
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For example, horseshoe bat produces high frequency sound, and detects the pressure of echoes produced from the objects.
Strategy # 7. Warning Colouration:
The conspicous markings of an animal that make it easily recognisable and warm would-be predators that it is a poisonous, foul-tasting, or dangerous species.
For example, the brightly colored and highly poisonous dart frogs (Phylobates bicolour), of the tropical rain forests of South America are easily recognised and avoided by the predators. The other example is the yellow and black striped abdomen of the wasp warns of its sting.
Strategy # 8. Water Scarcity:
Two main types of adaptations are found in animals of arid regions, i.e., (i) lowering of water loss as much as possible and (ii) adapting to arid conditions.
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The examples are as follows:
The kangaroo rat conserves water by excreting solid urine, and can live throughout life without drinking water.
On the other hand, the camels show unique adjustments to desert conditions. They are very economical in water use they can tolerate the wide fluctuations in body temperature and can maintain blood stream moisture even during extreme heat stress.
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Strategy # 9. Cold:
Some sessile animals, such as barnacles and molluscs which live in very cold inter-tidal zones of northern shores, and several insects and spiders resist the effect of cold spells by a process known as cold hardening.
The organisms that tolerate freezing conditions passes ice nucleating proteins which induce ice formation in the extracellular spaces at low rule zero temperatures.
While some free-avoiding animals can tolerate environmental temperature below 0°C by accumulating glycerol or antifreeze proteins that lower freezing point of their body fluids. Presence of such antifreeze substances allows the fish in Antarctica region to remain active in sea water.
