BiologyChapter 8: Thermoregulation and Homeostasis

8.3.2 Problems Faced By Osmoregulators

Problems Faced by Osmoregulators:

Osmoregulators face different problems depending on their habitat. Freshwater animals live in a hypotonic environment, marine teleosts live in a hypertonic environment, and terrestrial animals face the problem of dehydration.

Definition

Problems Faced by Osmoregulators: Since freshwater animals live in hypotonic environment, therefore, water constantly enters the body and they also face deficiency of salts, so they have to lose excess water and maintain higher salt concentration than their environment. On the other hand, most of the marine teleosts (bony fishes) are hypotonic to sea water. So these fishes have problem to lose water to the environment, especially across the gill epithelium. They also have problem of excess of salts in the body due to drinking of sea water. Terrestrial animals are also hypotonic to the outer environment. Evaporation of water that leads to the dehydration is the major problem faced by these animals.

Main Idea

Osmoregulators face different problems depending on their habitat.
Freshwater animals:
Live in hypotonic environment.
Water constantly enters the body.
Face deficiency of salts.
Have to lose excess water.
Have to maintain higher salt concentration than environment.
Marine teleosts (bony fishes):
Are hypotonic to sea water.
Have problem to lose water to the environment.
Especially across the gill epithelium.
Have problem of excess of salts in the body due to drinking of sea water.
Terrestrial animals:
Are hypotonic to the outer environment.
Evaporation of water leads to dehydration.
Dehydration is the major problem.

Core Concept

Freshwater animals = hypotonic environment; water enters; salt deficiency
Marine teleosts = hypotonic to sea water; water loss; excess salts
Terrestrial animals = hypotonic to environment; dehydration
Freshwater animals = lose excess water; maintain higher salt concentration
Marine teleosts = drink sea water; excess salts
Terrestrial animals = evaporation; dehydration

Detailed Explanation

Problems Faced by Osmoregulators

Since, freshwater animals live in hypotonic environment, therefore, water constantly enters the body and they also face deficiency of salts, so they have to lose excess water and maintain higher salt concentration than their environment.
On the other hand, most of the marine teleosts (bony fishes) are hypotonic to sea water.
So these fishes have problem to lose water to the environment, especially across the gill epithelium.
They also have problem of excess of salts in the body due to drinking of sea water.
Terrestrial animals are also hypotonic to the outer environment.
Evaporation of water that leads to the dehydration is the major problem faced by these animals.

Summary Table of Problems Faced by Osmoregulators

Habitat	Problem	Solution
Freshwater	Water enters; salt deficiency	Lose excess water; maintain higher salt concentration
Marine	Water loss; excess salts	Drink sea water; excrete excess salts
Terrestrial	Dehydration	Conserve water

Detailed Description of Problems

Habitat	Problem	Description
Freshwater	Water enters	Water constantly enters the body
Freshwater	Salt deficiency	Face deficiency of salts
Freshwater	Excess water	Have to lose excess water
Freshwater	Salt concentration	Have to maintain higher salt concentration than environment
Marine	Water loss	Lose water to the environment, especially across gill epithelium
Marine	Excess salts	Excess of salts in the body due to drinking of sea water
Terrestrial	Dehydration	Evaporation of water leads to dehydration

Intermediate Level

Problems Faced by Osmoregulators

Habitat	Problem	Description
Freshwater	Water enters	Water constantly enters the body
Freshwater	Salt deficiency	Face deficiency of salts
Freshwater	Excess water	Have to lose excess water
Freshwater	Salt concentration	Have to maintain higher salt concentration than environment
Marine	Water loss	Lose water to the environment, especially across gill epithelium
Marine	Excess salts	Excess of salts in the body due to drinking of sea water
Terrestrial	Dehydration	Evaporation of water leads to dehydration

Solutions to Problems

Habitat	Problem	Solution
Freshwater	Water enters; salt deficiency	Produce large volume of diluted urine; reabsorb salts
Marine	Water loss; excess salts	Drink sea water; excrete excess salts
Terrestrial	Dehydration	Conserve water; behavioral adaptations

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

1. Osmoregulators face different problems depending on habitat.
2. Freshwater animals live in hypotonic environment.
3. Water constantly enters the body of freshwater animals.
4. Freshwater animals face deficiency of salts.
5. Freshwater animals have to lose excess water.
6. Freshwater animals have to maintain higher salt concentration.
7. Marine teleosts are hypotonic to sea water.
8. Marine teleosts lose water to the environment.
9. Marine teleosts lose water across gill epithelium.
10. Marine teleosts have excess salts in the body.
11. Marine teleosts drink sea water.
12. Terrestrial animals are hypotonic to the outer environment.
13. Evaporation of water leads to dehydration.
14. Dehydration is the major problem for terrestrial animals.
15. Osmoregulation is essential for survival.

Remember

- Freshwater animals = hypotonic environment; water enters; salt deficiency
- Marine teleosts = hypotonic to sea water; water loss; excess salts
- Terrestrial animals = hypotonic to environment; dehydration
- Freshwater animals = lose excess water; maintain higher salt concentration
- Marine teleosts = drink sea water; excess salts
- Terrestrial animals = evaporation; dehydration

Common Mistakes

1. Confusing the problems of freshwater and marine animals — Freshwater = water enters; marine = water loss.
2. Mixing up the solutions — Freshwater = dilute urine; marine = drink sea water.
3. Forgetting the role of gills in marine teleosts — Site of water loss and salt excretion.
4. Mixing up the tonicity — Freshwater = hypotonic; marine = hypotonic to sea water.
5. Forgetting the problem of terrestrial animals — Dehydration.
6. Believing all marine animals have the same problems — Marine teleosts are hypotonic to sea water.
7. Mixing up the types of animals — Freshwater animals are osmoregulators.
8. Forgetting the role of the kidneys — Produce dilute urine in freshwater animals.
9. Thinking osmoregulation is not important — It is essential for survival.
10. Mixing up the habitats — Freshwater, marine, terrestrial.

Quick Revision

Since, freshwater animals live in hypotonic environment, therefore, water constantly enters the body and they also face deficiency of salts, so they have to lose excess water and maintain higher salt concentration than their environment. On the other hand, most of the marine teleosts (bony fishes) are hypotonic to sea water. So these fishes have problem to lose water to the environment, especially across the gill epithelium. They also have problem of excess of salts in the body due to drinking of sea water. Terrestrial animals are also hypotonic to the outer environment. Evaporation of water that leads to the dehydration is the major problem faced by these animals.

60-Second Revision

Freshwater animals = hypotonic environment; water enters; salt deficiency
Marine teleosts = hypotonic to sea water; water loss; excess salts
Terrestrial animals = hypotonic to environment; dehydration
Freshwater animals = lose excess water; maintain higher salt concentration
Marine teleosts = drink sea water; excess salts
Terrestrial animals = evaporation; dehydration
Warning: Freshwater animals face water gain; marine teleosts face water loss; terrestrial animals face dehydration

NEXT TOPIC

Chapter:
8. Thermoregulation and Homeostasis

Topic:
8.3.3 OSMOREGULATORY ADAPTATIONS IN ANIMALS

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