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Explore the concept of food chains and food webs to understand the flow of energy in ecosystems. Learn about carnivores, decomposers, omnivores, herbivores, and more. Discover how changes in food webs can impact species.
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KEY CONCEPT Food chains and food webs model the flow of energy in an ecosystem. Is this a food chain or food web? What can we infer from this diagram?
GRAMA GRASS DESERT COTTONTAIL HARRIS’S HAWK A food chain is a model that shows a sequence of feedingrelationships. • A food chain links species by their feeding relationships. • A food chain follows the connection between one producer and a single chain of consumers within an ecosystem. What do you notice about the arrows? Which organism is at the top of this food chain?
carnivore Decomposer Detritivore • Herbivores eat onlyplants. Ex. Rabbit • Carnivores eat only animals. Ex. Lion • Omnivores eat both plants and animals. Ex. Bear • Detritivores eat dead organic matter. Ex. earthworm • Decomposers are detritivores that break down organic matter into simpler compounds. Ex. Bacteria, fungi • Consumersare not all alike.
Specialists are consumers that primarily eat one specific organism or a very small number of organisms. • Changes in food web can cause extinctions • Ex. Florida snail kites feed mainly on apple snails. Water quality in the FL Everglades has declined and with it, Everglade Snail Kite populations have as well. Why? • Generalists are consumers that have a varying diet. • Changes in the environment/food web are easier to handle since they have alternative means for food
Primary consumers are herbivores that eat producers. • Secondary consumers are carnivores that eat herbivores. • Tertiary consumers are carnivores that eat secondary consumers. • Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains. • Trophic levels are the nourishment levels in a food chain.
Food web or food chain? Justify your answer.
A food web shows a complex network of feeding relationships. • An organism may have multiple feeding relationships in an ecosystem. • A food web emphasizes complicated feeding relationships and energy flow in an ecosystem. Which creature consumes the most in this web? The least? Do any have no predator in this web?