Ecosystem and Food Chain Basics

Ecosystem and Food Chain

• An ecosystem is the complex whole of organisms living in an area, along with their interactions.
• Interactions between organisms include feeding to obtain energy, which is represented by a food chain.
• A food chain shows the feeding interactions in an ecosystem, depicting who eats whom and the flow of energy.

Food Chain Examples

• Terrestrial food chain: grass -> plant-eating insects -> meat-eating insects -> frog -> snake -> bird of prey
• Marine food chain: algae -> plankton -> crustaceans -> fish -> dolphin -> shark

Energy Flow in an Ecosystem

• Energy cannot be created or destroyed, but is transferred from organism to organism within an ecosystem through feeding.
• Energy flows from producers to consumers, in one direction, as each organism eats the one below it on the chain.

Trophic Levels

• Trophic levels describe the levels of energy flow in the food chain, classifying where an organism falls within an ecosystem.
• Energy flows from producers (lowest trophic level) to quaternary consumers (highest trophic level).
• The trophic levels can be visualized as a pyramid, with producers at the base and quaternary consumers at the top.

Trophic Level Classification

• Producers (autotrophs): create their own food through photosynthesis or chemosynthesis.
• Primary consumers: feed on producers, exclusively herbivores.
• Secondary consumers: feed on primary consumers, can be carnivores or omnivores.
• Tertiary consumers: feed on secondary consumers, typically predators, can be carnivores or omnivores.
• Quaternary consumers: apex predators, feed on tertiary consumers and below, typically carnivores but can be omnivores.

Herbivores, Carnivores, and Omnivores

• Herbivores: feed exclusively on plant matter, primary consumers.
• Carnivores: feed exclusively on meat, can feed at secondary consumer trophic level or above.
• Omnivores: feed on both plants and meat, can feed at all trophic levels from primary to quaternary consumers.

Food Web

• A food web represents all of the food chains within an ecosystem and shows how feeding relationships between organisms are interconnected.
• Energy flows in an upward trend from the lowest trophic level of producers to the highest trophic levels of quaternary consumers.
• Energy can flow between organisms in different food chains, as shown by the food web.

Energy Flow in a Food Web

• Energy is not transferred perfectly from one trophic level to the next, with a 10% rule of thumb for energy transfer.
• The remaining 90% of energy may be lost due to heat, metabolism, or matter not consumed.
• This energy flow pattern is not limited to a single food chain, but occurs throughout the entire ecosystem.