Question
Describe the morphological, physiological, and behavioural adaptations of organisms living in desert, aquatic, mountain, and forest environments. Give specific examples.
(NEET + CBSE Class 12)
Solution — Step by Step
| Organism | Adaptation | Type |
|---|---|---|
| Camel | Concentrated urine, fat storage in hump (not water), tolerates body temperature fluctuation | Physiological |
| Kangaroo rat | Gets water from metabolic oxidation of food, never drinks water | Physiological |
| Cactus (Opuntia) | Leaves reduced to spines (reduce water loss), stem stores water, CAM photosynthesis | Morphological |
| Desert lizard | Basks in sun when cold, hides in shade when hot | Behavioural |
Desert organisms minimise water loss through reduced surface area, concentrated excretory products, and nocturnal activity.
| Organism | Adaptation | Type |
|---|---|---|
| Fish | Streamlined body, gills for dissolved O₂, swim bladder for buoyancy | Morphological |
| Whale | Blubber for insulation, can hold breath long, echolocation | Physiological |
| Aquatic plants | Thin leaves (no need for water conservation), aerenchyma (air spaces for buoyancy) | Morphological |
| Organism | Adaptation | Type |
|---|---|---|
| Yak | Thick fur, large lungs (thin air at high altitude) | Morphological |
| Humans at high altitude | Increased RBC count, higher haemoglobin, faster breathing | Physiological (acclimatisation) |
| Seal | Thick blubber, reduced blood flow to extremities | Morphological + Physiological |
| Allen’s rule | Animals in cold climates have shorter ears, limbs (less surface area for heat loss) | Morphological pattern |
Adaptation Type by Environment
flowchart TD
A["Adaptations"] --> B["Morphological — body structure changes"]
A --> C["Physiological — body function changes"]
A --> D["Behavioural — activity pattern changes"]
B --> B1["Desert: spines instead of leaves"]
B --> B2["Aquatic: streamlined body, gills"]
B --> B3["Cold: thick fur, blubber"]
C --> C1["Desert: concentrated urine"]
C --> C2["Altitude: more RBCs, more haemoglobin"]
C --> C3["Aquatic: swim bladder for buoyancy"]
D --> D1["Desert: nocturnal activity"]
D --> D2["Cold: hibernation"]
D --> D3["Migration to warmer areas"]Why This Works
Adaptations are the result of natural selection — over many generations, individuals with features suited to their environment survive and reproduce more. The environment applies selection pressure, and the organisms evolve matching adaptations.
Three important ecological rules govern animal body size and shape in different climates:
- Allen’s rule: Shorter extremities in cold climates (less heat loss)
- Bergmann’s rule: Larger body size in cold climates (lower surface-to-volume ratio)
- Both relate to thermoregulation — the core survival challenge in extreme environments.
Common Mistake
Students often say camels store water in their humps. Camels store fat in their humps, not water. The fat can be metabolised to produce water (metabolic water) when needed, but the hump itself is a fat reserve, not a water tank. Also, acclimatisation (like increased RBCs at high altitude) is a short-term physiological response, NOT a genetic adaptation. It happens within an individual’s lifetime and is reversible. NEET distinguishes between adaptation (evolutionary, genetic) and acclimatisation (physiological, temporary).