Contents
From genetics to ecology, Biology Topics cover a vast array of life sciences.
Characteristics of Terrestrial Habitats in Deserts and Its Adaptations
Some of the important terrestrial habitats are :
- Deserts,
- Mountain regions, and
- Forests (or Grasslands).
We will now describe the environment of all these terrestrial habitats and adaptations of plants and animals living in these habitats.
1. Deserts
A waterless area of land covered with sand and having little or no vegetation (plants, etc.) is called a desert. The dominant factors in the desert habitat are scarcity {shortage) of water and high temperature. In such conditions, the plants and animals have to protect themselves from excessive loss of water and too much heat. The plants and animals in deserts have developed special features for surviving in hot and dry areas of desert. We have already discussed the adaptation of camel to the desert habitat. We will now describe the adaptation of some other animals as well as plants to the desert habitat.
Adaptation in Desert Animals
In desert, there are animals like desert rats and desert snakes which do not have long legs like camels to keep their body away from hot desert sand. The animals like desert rats and desert snakes survive in the hot desert having lack of water due to the following adaptations :
1. The desert animals such as desert rats and desert snakes survive by living in burrows during the hot daytime (see Figure). The desert rats and snakes dig deep burrows in the sand and stay in them during daytime when it is very hot. The burrows stay cool during the day and hence protect these animals from the sun’s heat as well as loss of water from their body. The desert rats and desert snakes come out of the burrows only during cool night in search of food.
2. The desert animals such as desert rats and desert snakes pass out very small amount of urine and hence conserve water in their body. In this way, desert animals are adapted to cope up with lack of water in their habitat.
Adaptation in Desert Plants
In the hot desert habitat, water is not available to plants in sufficient quantity round the year due to meagre rainfall. Moreover, the high temperature in hot desert increases the evaporation of water from the leaves. The plants in desert habitat are well adapted to cope with the shortage of water and high temperature by storing water (when available) and reducing the loss of water. Some of the adaptations which help the desert plants to survive in hot and dry environment of a desert are as follows :
1. The leaves in desert plants are either absent, very small or present in the form of spines (thorns). This helps in reducing the loss of water from the leaves through transpiration. Since desert plants lose very little water through transpiration, they can survive on stored water for a long time.
2. In most of the common plants, the process of food making called “photosynthesis” is carried out by the leaves. Since the leaves of desert plants are either absent, very small or form spines, the stems of desert plants are modified to perform the functions of leaves. Thus, in desert plants photosynthesis is usually carried out by their green stems.
3. The stems of desert plants are modified for storing water. The stems of desert plants are also covered with a thick waxy layer (called cuticle) which prevents the loss of water from it.
4. Most of the desert plants have long roots which go deep into the soil for absorbing water.
Cactus is the most common plant found in deserts. The adaptations which help the cactus plants to survive in the hot and dry environment of a desert are given below.
(i) The cactus plants have modified their leaves in the form of thin spines (or thorns) to reduce the loss of water through transpiration (see Figure). Since cactus plants lose very little water through transpiration, they can survive in desert on the stored water for a long time.
(ii) The photosynthesis in cactus plants is carried out by the green stem. The green leaf-like structures which we see in a cactus plant is actually its stem (see Figure).
(iii) The cactus plants store water in their stems. The stem of a cactus plant is covered with thick waxy layer (called cuticle) which prevents the loss of water from it through evaporation.
(iv) The cactus plants have long roots to absorb water from a larger area.
Activity
The fact that a desert plant such as cactus loses very little water through transpiration can be shown as follows : Take a potted cactus plant and a potted leafy plant. Tie separate polythene bags to some parts of both the plants. Keep both these plants in sunshine for a few hours. After a few hours we will see that only a very small amount of water droplets are present in the polythene bag tied to the cactus plant but a lot more water drops are present in the polythene bag tied to the leafy plant (The water drops are formed by the condensation of water vapour lost by the plants through transpiration). This activity shows that a cactus plant loses very little water through the process of transpiration (evaporation from leaves).