SYMBIOSISFrom http://www.megalink.net/~tlight/symbiosis.html

Symbiosis

Symbiosis is a situation in which 2 different organisms live together in close association. Just living in the same place is not enough. By "close association" biologists mean that if they are separated, one (or both!) of these organisms will probably die.

Symbiosis

There are 3 types of symbiosis, Mutualism, Parisitism, and Commensalism.

Mutualism

Mutualism is when both organismsbenefit from therelationship.

In this picture, antsare living in ayoung acacia plant.

Mutualism

The ants have a home inside the hollow stem of the acacia. (Can you see the hole they are going in and out of?) They also get sugar from the plant. The acacia produces small spots of sugar at the base of each leaf. (The brown spot opposite the hole is a sugar gland.)

Mutualism

The plant also needs to benefit, and if you try to munch on the acacia's leaves, you will know why! The ants attack anything foolish enough to try to damage the acacia's leaves.

Parasitism

Parasitism is when one organism benefits and one is hurt by the relationship.

Parasitism

This strangler fig growing on another tree is an example of parasitism. The fig is getting support so it can grow quickly and get more sunlight.

Parasitism

Although the fig doesn't really strangle the tree, it does make it harder for the tree to get water and nutrients from the soil and also blocks some of the sunlight from reaching the tree's leaves.

Commensalism

Commensalism is a relationship in which one organism benefits and the other is not affected. Orchids can illustrate this.

Commensalism

Orchids are epiphytes (plants that grow on other plants). They grow high in the canopy of rainforests on the branches of trees. The orchids benefit in several ways. The main benefit is probably that they can get more sunlight. In addition, they may be more easily visited by the moths which pollinate them. Also, because they are up high the wind can more easily catch and spread their tiny seeds.

Commensalism

Orchids do not harm the trees they grow in. Their roots stay on the bark of the tree; they do not take water or nutrients from the tree.