How do living things interact? Habitats have an unlimited amount of the resources needed by living organisms, such as food, water and shelter. All organisms strive to reproduce themselves and increase their numbers. Sooner or later the demand for these resources is going to exceed supply, and organisms have to compete with each other to get them.

Plants typically compete with each other for:  light (for photosynthesis)  water  nutrients (minerals) PLANTS

Animals Animals typically compete with each other for:  food  water  mates (so they can reproduce), and  living space (shelter)

Symbiosis Some organisms survive and reproduce by living closely together with another organism of a different species. This type of interaction between organisms is known as symbiosis.

Commensalism Barnacles will attach to a whale or scallop shell. The barnacles get a home,access to food and transportation. The whale or scallop is not harmed from having the barnacle attach itself to them. This type of symbiosis, where one organism benefits and the other suffers no harm, is called commensalism.

Mutualism Lichens are formed by algae and fungi living together. Algae can photo-synthesize and make food which is shared by the fungus. The fungus in turn shelters the algae from a harsh climate. This kind of mutually beneficial co-operative interaction is called mutualism.

Parasitism A tapeworm lives inside another animal, attaching itself to the host and absorbs food from the host's food as it is digested. This kind of one-sided symbiosis is called parasitism. Usually parasites do not kill the host before they move on, as this would cut off their food supply.

REVIEW Which type of interaction does this picture show? A. Parasitism B.Comensalism C. Symbiosis D. Mutualism

And the answer is…… If you chose “B” Commensalism you are correct!!

Review Parasitism is best described by the following examples: A. Owl and yucca plant B. Butterfly and flower C. Flea and Dog D. Clown fish and Anemone

And the answer is…. Pat yourself on the back if you chose answer “C”, Flea and Dog. The flea survives by getting its nourishment from dog.

What kind of interaction does this picture show? A. Mutualism B. Parasitism C. Commensalism D. Phosphorism REVIEW

Answer #4 Congratulations if you chose Answer “A”. This interaction is an example of Mutualism. Although lichens come in a wide variety of forms and structures, all lichens are essentially a sandwich with a layer of fungi on the outside with a filling of an algal species on the inside.

Resources: eclips/ages/8_9/habitats.shtml Photos: