Mutualism

Definition

• Mutualism is a type of biological relationship in which both species benefit from their interaction, creating an interdependent relationship.

Examples of Mutualism

1. Herbivores and Cellulose-Digesting Microorganisms

• Many herbivores, like cows and termites, have cellulose-digesting protozoa or bacteria living in their digestive systems.

Benefits:

• The herbivore provides a warm, moist environment with a constant food supply for the microorganisms.
• Microorganisms break down cellulose, allowing the herbivores to access nutrients from their cellulose-rich diet.

2. Cleaner Fish and Larger Fish

• 'Cleaner' fish feed off the dead skin and parasites of larger fish such as sharks.

Benefits:

• Cleaner fish gain food and protection from larger fish, which do not attack them.
• Larger fish stay clean and are less prone to infections.

---

Mutualism

3. Lichens (Algae and Fungi)

• Lichens are formed by algae and fungi living together.

• Benefits:

• Algae can photosynthesise and produce food, which is shared with the fungus.

• The fungus shelters the algae from harsh environmental conditions.

4. Leguminous Plants and Nitrogen-Fixing Bacteria

• Leguminous plants, such as peas and beans, have colonies of nitrogen-fixing bacteria in nodules attached to their roots.

• Benefits:

• The plants gain nitrates from the bacteria, which enrich the soil with essential nutrients.

• The bacteria receive sugars from the plants, which they use for energy.

Summary

• Mutualism is a biological relationship where both species benefit from their interaction.
• Examples include herbivores and cellulose-digesting microorganisms, cleaner fish and larger fish, lichens formed by algae and fungi, and leguminous plants with nitrogen-fixing bacteria.
• In each case, the interaction enhances the survival and well-being of both species involved.