2. FOOD RELATIONSHIPS AMONG LIVING
ORGANISMS
• Food is the main source of energy for all living organisms.
• Green plants have the ability to benefit from sunlight as a source of
energy during photosynthesis process to make their own food from
simple substances (carbon dioxide gas and water) .
• Animals depend directly or indirectly on plants in their feeding.
3. The types of food relationships between
living organisms
Predation Symbiosis saprophytism
4. • "It is the food relationship among living organisms, where one living organism
devours another one“
• In predation, the living organisms get their food by
1) Attacking.
2) Killing.
3) Devouring the other organisms.
• The predator is the living organism which devours the other living organism.
• The prey is the devoured animal.
• Predation is a temporary relationship which ends up by devouring the prey or a part
of it.
5. • Plants are called autotrophic organisms (self – feeder organisms) as they make their own
food (carbohydrate and protein) by photosynthesis process.
• Predation is less common in plant world than in animal world.
• But, there are some plants that cannot make protein substances, because they cannot
absorb some compounds from the soil.
• These plants are known as insect eaters or insectivorous plants, because they have to prey
some tiny animals such as insects.
• Examples of insectivorous plants:
• 1. Drosera. 2. Halophila.
6. • There are many examples for predator animals such as lions, tigers, wolves,
cats and sharks.
• Examples :
1) A lion preys a deer. 2) A wolf preys a rabbit. 3) A cat preys a rat.
7. Many living organisms use different ways (methods to defend
themselves against enemies
such as:
A. Camouflage. B. Mimicry.
8. "A phenomenon in which the living organism protects itself (hides) from
enemies by changing its color to simulate the color of its surrounding
environment“
• This phenomenon is found in:
• Fish. - Frogs. - Birds. - Chameleon. - Most insects as butterflies.
9. 1. A butterfly stands on a tree with similar color.
2. A frog changes its color to hide from its enemies
3. A chameleon simulates the color of the surrounding environment.
4. A cuttlefish (sepia) ejects a black fluid in the surrounding water
when attacked by enemies.
