Answer: Regulators keep their internal environment constant; conformers let it change with the surroundings; migrants move away temporarily to a favourable place.
- (a) Regulate: some organisms maintain homeostasis, i.e. a constant body temperature and osmotic concentration, by physiological (and sometimes behavioural) means even when the external conditions change. Example: birds and mammals keep body temperature near 37 °C by sweating in summer and shivering in winter.
- (b) Conform: most animals and nearly all plants cannot regulate; their body temperature or osmotic concentration changes with that of the surroundings. Example: body temperature of fish and frogs changes with water temperature; osmotic concentration of many marine invertebrates equals that of sea water.
- (c) Migrate: the organism moves temporarily from the stressful habitat to a more favourable area and returns when the stressful period is over. Example: Siberian cranes migrate to Bharatpur (Keoladeo National Park) in winter.
(Other responses are suspending activity, e.g. hibernation, aestivation, seed dormancy, and partial regulation.)
