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A stage of suspended development, zooplanktons.

Because it affects the enzyme activity.

Euryhaline : Organisms tolerant in wide range of salinities.

Stenohaline : Organisms tolerant to narrow range of salinities.

Sigmoid curve, population becomes stable due to environmental resistance. 

Clown fish lives in tentacles of sea Anemone and gets protection from predators. 

Interaction – commeasalisn.

Clown fish gets protection from its predators by moving around the stinging tentacles of the sea anemone. The sea anemone is neither helped nor harmed by the interaction with the fish This relationship is called Commensalism.

Detailed Answer: 

Clown fish maintains a commensalistic relation with the sea anemone. In this interaction, one species benefits and the other is neither harmed nor benefited. Sea anemone has stinging tentacles that provide protection to clown fish from predators. The anemone does not appear to derive any benefit from the clown fish.

Eurythermales are the organisms which can tolerate and live in a wide range of temperature while stenohalines can tolerate only a narrow range of salinities.

(a) (i) A relatively constant internal (within the body) environment permits all biochemical reaction and physiological function to proceed with maximum efficiency and, thus, enhance the overall 'fitness' of the species. Hence, the living system always tends to remain in a steady state with the help of a self-regulatory mechanism. Such a phenomenon, which involves the maintenance of a constant internal environments, is known as homeostasis. 

(ii) Regulate : Maintain homeostasis by ensuring constant body temperature (thermoregulation) and constant osmotic concentration (osmoregulation).

(iii) Conform : Change the internal environments with the external environment. 

(b) Living organisms cope with stressful external environmental conditions in many ways, such as : 

(i) Regulate : Maintain homeostasis by ensuring constant body temperature (thermoregulation) and constant osmotic concentration (osmoregulation). 

Example : Mammals regulate body temperature by shivering in cold and sweating in heat. 

(ii) Conform : The internal environment of conformers changes with the external environment. 

Example : In aquatic animals, the osmotic concentration of the body fluids changes with that the ambient water osmotic concentration. 

(iii) Migrate : Some organisms move from a stressful habitat to a hospitable area temporarily and return when the stressful period is over. 

Example : Every winter, migratory birds come from Siberia to Keoladeo National Park, Rajasthan. 

(iv) Suspend : In higher plants, seeds and some other vegetative reproductive structures serve as means to tide over periods of stress besides helping in dispersal-they germinate to form new plants under favourable moisture and temperature conditions.

Due to osmotic problems.

Marine water has high salt concentration. The fresh water animals in such hypertonic conditions suffer from osmotic problems. Their bodies start losing water by exosmosis. Therefore it is difficult for fresh water animals to survive in marine environment.

The calotropis plant produces highly poisonouss cardiac glycosides show a chemical defense against the herbivores.