Some animals live in arid regions, while some animals thrive in polar regions.
Plants in the tropical rainforests have drip tips and thick, waxy surfaces that allow water to run off while desert plants have spongy stems which store water and leaves reduced to tiny pointed spines.
On our planet, every organism adapts to stressful environmental conditions through morphological, physiological and behavioural means.
In fact, the responses of these organisms are their adaptations to cope in unfavourable or stressful conditions. In other words, adaptation is any attribute of the organism that enables it to survive and reproduce in its habitat. Let’s look at some of the morphological adaptations exhibited by organisms.
Over the course of evolution, many adaptations have evolved and have been genetically fixed.
Although life originated in water and is unable to sustain without it, some organisms can survive without water for days.
In the case of the kangaroo rat in the North American deserts, the animal meets its water requirements by metabolic water. Metabolic water is released as a by-product during oxidation of fat in its body.
The body of this rodent is also capable of concentrating its urine so that very little water is used to remove waste products.
Likewise, the camel can also survive without water for 10 days at a stretch and is capable of raising its body temperature to nearly 420C to prevent the loss of water.
Similarly, many desert plants have a thick layer of cuticle on their leaves with their stomata embedded in deep pits to reduce the loss of water through transpiration.
These plants have also adopted a special photosynthetic pathway called CAM or Crassulacean acid metabolism, which enables their stomata to remain closed during the day.
Some desert plants like the Opuntia have leaves that are reduced to spines and its flattened, spongy stems perform photosynthesis.
While some plants and animals have adapted to prevent the loss of water, some animals, particularly those found in colder regions, have adapted themselves to prevent the loss of heat.
For instance, mammals from colder climates generally have shorter tails, limbs and ears, which help reduce loss of heat. This adaptation is called Allen’s Rule.
Moreover, in the polar seas, aquatic mammals such as seals, whales and dolphins have a thick layer of fat known as blubber below their skin, which acts as an insulator and minimises the loss of body heat.
Apart from morphological adaptations, some organisms physiologically adapt themselves to respond to stressful situations.