Symbiosis Notes

Symbiosis and Symbiotic Relationships

Overview

• Symbiosis: A relationship in which two species live closely together. These relationships between species can result in benefit, harm, or have no effect on one or both species involved.

• Symbiotic relationships occur to fulfill basic needs such as food, shelter, and protection/safety.

Types of Symbiotic Relationships

1. Mutualism [+ | +]

• Occurs when both organisms benefit.

• Example 1: Birds get nectar from a flower while pollinating the flower in return.

• Example 2: Ants sting predators of the Acacia plant for the plant's protection; in return, the ants get food and a place to live.

2. Commensalism [+ | 0]

• Occurs when one organism benefits, and the other organism neither benefits nor is harmed.

• Example: Epiphyte (orchid) makes its own nutrients and grows on a tree to reach sunlight, without harming the tree.

3. Parasitism [+ | -]

• Occurs when one organism (the parasite) benefits and the other (the host) is harmed.

• Example: Mistletoe takes nutrients away from trees.

4. Predation [+ | -]

• Occurs when one organism (the predator) hunts another organism (the prey) for food.

• Example: A cougar hunts, kills, and eats a deer.

Competition

• An interaction between organisms in which both organisms are harmed.

• Occurs when species occupy the same niche.

• The species that is best adapted to complete the job will usually fill the niche.

Niche

• All the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce in an ecosystem.

Competition Example

• Asian carp, an invasive species accidentally introduced into the Illinois and Mississippi Rivers, outcompete native fish for food and habitat. They are voracious filter feeders and can grow to over 100 lbs.