How do different organisms living in the same community help each other?

In the Film

Terns gain protection from predators by living among a colony of gulls. A baby leather bass fish finds protection among sea urchins. Small jack fish swim, unharmed, among the tentacles of the lion's mane jellyfish, while angelfish clean parasites off a manta ray

Concept

Organisms of different species may live together in beneficial relationships.

Objective

To invent two organisms with attributes that allow them to live together as helpful partners

Content

Science, language arts, visual arts

Background

Within communities, organisms of different species may exist in some form of partnership. These relationships are generally referred to as symbiotic. Mutualism refers to relationships that are beneficial to both organisms. The relationship of flowers and bees is an example of mutualism. A bee moves pollen from one flower to another, thus fertilizing the flowers. At the same time, the bee satisfies its need for food by feeding on nectar produced by the flower. In some relationships, one organism may benefit while the other organism neither gains nor loses. Referred to as commensalism, an example of this type of relationship might be a bird nest in a tree. The bird finds a place to build a nest (benefits), while the tree neither gains nor loses. Parasitism, a third type of relationship, is beneficial to one organism at the expense of another. Fleas on a dog would be an example of parasitism.

On the Web

The Ocean Oasis Field Guide has pages with photographs and more detailed information about most of the species mentioned here.

Description of organisms, paper, pencil, art supplies

(six groups)

• Discuss the types of partnerships that might exist between different organisms in a community—mutualism, commensalism, parasitism.
• Explain that the class will pretend to operate a "dating service" for marine animals. Requests have been received from six animals seeking helpful relationships. Divide the class into six groups. Give each group one of the request sheets.
• Each group designs a poster portraying their client with a list of attributes.
• Display the finished posters.
• Challenge each group to find a partner for their animal that will result in a beneficial relationship for one or both members.
• Describe the relationship between your two partners.

SUGGESTED PAIRINGS
manta (1) with young angelfish (2) = mutualism
sea urchin (3) with baby leather bass (4) = commensalism
jack (5) with lion's mane jellyfish (6) = mutualism

Local Connection
Describe some relationships between organisms in your area that exhibit mutualism, commensalism, or parasitism.

Key Words
symbiotic, mutualism, commensalism, parasitism

Continue to Activity 12: Human Needs and Resources: Comparing Lifestyles