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ZingPath: Interactions Among Organisms

Parasitism in Ecosystems

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Interactions Among Organisms

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Lesson Focus

Parasitism in Ecosystems

Life Science

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You will learn about parasitism in marine, freshwater, and terrestrial ecosystems.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Describe parasite/host relationships as they occur in food webs within marine ecosystems.
  • Describe parasite/host relationships as they occur in food webs within freshwater ecosystems.
  • Describe parasite/host relationships as they occur in food webs within terrestrial ecosystems.

Everything You'll Have Covered

Food chains and food webs describe the same series of events that happen when one organism consumes another to survive. There are many connections for every organism in a food web. For example, a cow might be food for humans, bacteria, and flies.

Every food chain has producers and consumers. Producers are plants. They make their own food through photosynthesis. Consumers are animals. They can't make their own food, so they need to eat plants and animals to survive.

There are three types of consumers: herbivores, carnivores, and omnivores. Herbivores are animals that eat only plants. Carnivores eat only meat. Omnivores eat both. Humans are omnivores.

Predators are organisms that eat other organisms. The organisms they eat are called prey. Some examples of predator/prey relationships are lions and zebras, bears and fish, and foxes and rabbits.

Similar to the predator/prey relationship is the parasite/host relationship. A parasite is an organism that lives on or in another organism. The organism that is harmed by the parasite is called the host.

Consumer/producer, predator/prey, and parasite/host relationships occur in food chains and food webs in different ecosystems such as marine, freshwater, and terrestrial ecosystems. A marine ecosystem includes all living organisms in an ocean environment. A freshwater ecosystem includes all living organisms in a freshwater environment, and a terrestrial ecosystem includes all living things on land.

Host specificity: It is important to note that most parasites are very particular about the host they can live in or on. Many parasites can only live and reproduce inside, or on, a single species of host, or on a few very closely related species. This is known as host specificity. The chance of a parasite successfully invading a different host increases when two host species are similar to each other. For example, certain ticks and fleas that have dogs as hosts could possibly attack humans. But, a marine parasite with a fish as its host is unlikely to be able to grow in, or on, a human. In the case of the tongue-eating louse, there is no chance that it can invade humans and destroy and replace our tongues if we go swimming in the ocean or eat the host fish for dinner.

Tutorial Details

Approximate Time 3 Minutes
Pre-requisite Concepts Students should be familiar with the terms ecosystem and symbiotic.
Course Life Science
Type of Tutorial Animation
Key Vocabulary freshwater ecosystems, host, marine ecosystems, parasite, parasitism, terrestrial ecosystems