Relationships in the Food Web Symbiotic relationships: “living together” Predation (+/-) Species hunt other species Parasitism (+/-) one species benefits, one is harmed Competition (+/-) Species “fight”/ “use” the same resources Commensalism (+/o) one species benefit, one is unbothered Mutualism (+/+) Both species benefit

Predation

Living Relationships Predator-Prey Relationship – beneficial for one species and harmful to another, involves a fight for survival. However, some species enhance their chances of survival by forming close, permanent relationships with other species - symbiosis.

Symbiotic Relationships cont. Parasitism – relationship in which one organism derives benefit at the expense of the other. Ticks are parasites of animals like dogs, obtaining nutrients from the blood of their host. Parasites harm, but usually do not kill, the host.

Parasitism

Competition This happens when 2 or more individuals strive to obtain the same resources when these are in short supply. The more similar the individuals are, the more intense the competition.

Competition

Commensalism

Symbiotic Relationships Commensalism – relationship in which one species benefits and the other species is neither harmed nor benefited The clownfish lives among the stinging tentacles of an anemone and is protected from potential predators not immune to the sting of the anemone.

Mutualism

Symbiotic Relationships cont. Mutualism – relationship in which both species benefit Some fish and shrimp clean the bodies and mouths of large fish and turtles. The cleaner fish get a meal while the large fish have parasites removed.

Community Interactions Predation- 12

Community Interactions Symbiosis- relationship where organisms live together 13

Community Interactions Mutualism 14

Community Interactions Mutualism 15

Community Interactions Commensalism 16

Community Interactions Parasitism 17

Ecological Succession Ecosystems are constantly changing in response to natural and human disturbances. older inhabitants die out new organisms move in series of predictable changes that occurs in a community over time 18

Primary Succession In this example, a volcanic eruption has destroyed the previous ecosystem. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. 19

The first organisms to appear are lichens. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. 20

Mosses soon appear, and grasses take root in the thin layer of soil. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. 21

Eventually, tree seedlings and shrubs sprout among the plant community. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. 22

Ecological Succession Components of an ecosystem can be changed by natural events, such as fires. When the disturbance is over, community interactions tend to restore the ecosystem to its original condition through secondary succession.  23

Marine Ecosystem Succession Succession begins when a whale dies and sinks to the ocean floor. Ecosystems are constantly changing in response to disturbances. In natural environments, succession occurs in stages. A dead whale that falls to the ocean floor is soon covered with scavengers. 24

Within a year, most of the whale’s tissues have been eaten by scavengers and decomposers. 25