ECOLOGYSymbiotic Relationships

COMPETITION Species living in the same habitat

may use the same resources. These species will compete for the

resource.

PREDATION A relationship between two species

Predator: captures and feeds on the other organism Prey: is the one that gets eaten.

In ecology this relationship is a form of population control. If there are not enough predators, too many

prey will exist, and vice versa

SYMBIOSISAny relationship in which two organisms live closely togetherMeans “living together”Three main classes of symbiotic relationships

PARASITISMIn a parasitic relationship one organism lives in or on another organism(the host) and harms itThe parasite gets its nutritional requirements from the host

The host is weakened, but usually does not die

PARASITISM

MUTUALISMBoth organisms benefit from the relationship.

MUTUALISM

COMMENSALISMOne organism benefits from the relationship while the other organism neither benefits nor is harmed

COMMENSALISM

ECOLOGYFood chains and food webs

TROPHIC LEVELSA trophic level is one of the steps in a food chain or pyramid

LEVEL ONEThis level is always the producers

Producers are organisms that first capture energyAka: autotrophs

Ex: plants, algae, some bacteria

CONSUMERSAn organism that consumes plants or other organisms to obtain energy

Consumers make up the rest of the trophic levels

Aka heterotrophs

LEVEL TWOThis level consists of herbivores-organisms that eat plants

Consumers on this level are called primary consumers

LEVEL THREEThis level consists of carnivores- organisms that eat other organisms for energy

They are called secondary consumers

LEVEL FOURConsumers on this level are called tertiary consumers

They are carnivores who eat other carnivores

OTHER ORGANISMS IN A FOOD WEB Detritivores-an organism that feeds on

organic waste Omnivores- organisms that eat both plants

and other organisms Decomposers- An organism who recycles

nutrients by feeding on dead or decaying organisms.

DetritivoreDecomposer Omnivore

WHAT IS THE DIFFERENCE BETWEEN A DETRITIVORE AND A DECOMPOSER?They both obtain energy from organic

matter (dead/decaying plants and animals), but…

The way they consume the organic matter is differentDetritivores actually eat the organic

matterDecomposers secrete enzymes that

break down the organic matter into small molecules and then consume those small molecules

FOOD CHAINA path of energy through the trophic levels of an ecosystem

FOOD WEBA diagram that shows the feeding relationships between organisms in an ecosystem

QUESTION:How are food chains and food webs related?

Several food chains make up a food web

TYPES OF FOOD WEBS Grazing food web: starts with plants in

the first trophic levelPlants get their energy from the sun

Detritus food web: starts with dead organic matter such as plants or animals

ENERGY LOSSAs you go up each trophic level energy is lost

Most energy is lost to the environment as heat

An organism stores about 1/10 of the energy stored by an organism in the level below it

ENERGY LOSS

The first trophic level starts with 100% energy.

200X .01 (10%)

20

2

0.2

PYRAMID OF BIOMASS

The decrease in energy going to up in levels means that there is less energy for animals to survive on.

Less energy means less animals.

This is referred to as a decrease in biomass