ECOLOGY ECOLOGY & &

FOODWEBSFOODWEBS

UNIT 2: S7L4Students will examine the dependence of

organisms on one another and their environments.A. Demonstrate in a food web that matter is

transferred from one organism to another and can recycle between organisms and their environments.

B. Explain in a food web that sunlight is the source of energy and that this energy moves from organism to organism.

C. Recognize that changes in environmental conditions can affect the survival of both individuals and entire species.

D. Categorize relationships between organisms that are competitive or mutually beneficial.

EQ’s to be answered in this unit:• How is life like a web?• Why is it necessary for everything in an

ecosystem to work together?• How do YOU fit into the larger world? • How does a change in temperature and/or

precipitation affect the living things in the environment?

• Why can’t there be a lone survivor?• What effect does the environment have on

organisms?• How does the environment affect us?

HabitatsAn environment that

provides the things that an organism needs to live,grow, and reproduce.

Organism A single living thing (plant, animal, fungus, protist, bacteria)

Needs food, water, & shelter

Organisms Interact With Both:

Biotic FactorsAny plant or animal; living things

Abiotic FactorsObjects that do not have living characteristics; non-living things

Example: water, sunlight, oxygen, temperature, soil

Population vs. Community Species

A group of organisms that are physically similar and can mate with each other

Example: bear Population

All members of one species in a particular area

Example: a group of deer in a forest Community

All different populations that live together in an area and are close enough to interact with each other

Example: birds, bears, snakes, all living in the forest

ECOSYSTEM The community of organisms that live in a particular area, along

with their nonliving surroundings, make up an ecosystem.

Example: Prairie, mountain streams, deep oceans, and forests

LEVELS of ORGANIZATION: Species: Prairie Dog Population: Prairie Dog Town Community: All the living things that interact

on the prairie (grass, prairie dogs, skunks) Ecosystem: All the living & nonliving things

that interact on a prairie (grass, owls, prairie dogs, snakes, sun, water, soil)

Where Does Energy Comes From?SUN

Provides energy for life on Earth

2 Ways To Obtain EnergyProducers

Organism that can make its own food using the Sun

Example: Plants

Consumers Organism that gets

energy by feeding on other organisms

Example: Animals

How Do They Get Energy? Here is how energy passes from one organism to

another.PRODUCERS will ALWAYS be first. Producers

make their own food.CONSUMERS will be next:

herbivoreAn organism that eats only plants (ex:

rabbit, deer)carnivore

An organism that eats other animals (ex: hawk, wolf)

omnivoreAn organism that eats both plants and

animals (ex: bear, human)

How Do They Get Energy? Here is how energy passes from one organism to

another.scavenger

A carnivore that feeds on the bodies of dead organisms (ex: vultures)

decomposer An organism that breaks down chemicals

from wastes and dead organisms, and returns important materials to the soil and water. (ex. fungi & bacteria)

Interactions of Living Things There are three major types of interactions among

organisms: Predation

An interaction in which one organism kills another for food

CompetitionThe struggle between organisms to survive

as they attempt to use the same limited resources

Symbiosis A close relationship between two species

that benefits at least one of the species

Interactions of Living Things An interaction in which one organism kills another

for food is called predation. A tiger shark lurks below the surface of the clear blue

water, looking for shadows of albatross chicks floating above. The shark spots a chick and silently swims closer. Suddenly, the shark bursts through the water and seizes the albatross with one snap of its powerful jaw. This interaction between two organisms has an unfortunate ending for the albatross.

predatorThe organism that does the killing

prey The organism that is killed

Interactions of Living ThingsThe struggle between organisms to survive

as they attempt to use the same limited resources is called competition.In any ecosystem, there is a limited

amount of food, water, and shelter. Organisms that survive have adaptations

that enable them to reduce competition.Adaptations are behaviors or physical characteristics that allow organisms to be successful in their environment.

NICHE-Organism SurvivalA Niche is the role of an organism in its

habitat, or how it makes its living.Consists of a variety of adaptations that

are suited to the organisms specific living conditions. How does it find food and shelter? How does it avoid danger? How does it care for its young? Does it have predators? Can it cooperate with other animals? Can it find prey (food)?

Interactions of Living Things A close relationship between two species that

benefits at least one of the species is called symbiosis.

There are three types of symbiotic relationships: Mutualism: A relationship in which BOTH

species benefit.

Commensalism: A relationship in which ONE species benefits and the other species is neither helped nor harmed.

Parasitism: A relationship in which one organism lives ON or IN another organism and HARMING it.

Interactions of Living Things A close relationship between two species that

benefits at least one of the species is called symbiosis. Mutualism: A relationship in which BOTH

species benefit. Example:

+ birds that ride on a rhino’s back

they eat bugs & ticks on the rhino’s back

they get food and the rhino gets clean

Interactions of Living Things A close relationship between two species that

benefits at least one of the species is called symbiosis. Commensalism: A relationship in which ONE

species benefits and the other species is neither helped nor harmed.

Example:

+ birds that build nests in tress

the bird now has shelter but the tree is not helped or harmed by this interaction.

Interactions of Living Things A close relationship between two species that

benefits at least one of the species is called symbiosis. Parasitism: A relationship in which one organism

lives ON or IN another organism and HARMING it.

A parasite is the organism that lives on or in another organism and is benefitting.

A host is the organism that the parasite is living

on or in.

Example: a tick living on a dog

Mutualism – Bees & Flowers

Commensalism – Fish & anemones

Parasitism – Ticks

ENERGY FLOWEnergy is transferred from one organism to another.

The movement of energy through an ecosystem can be shown in diagrams.

Two diagrams of energy transfersFood Chain/Food WebEnergy Pyramid

Tree Carpenter Ant Woodpecker

A food chain is a series of events in which one organism eats another and obtains energy.

The first organism in a food chain is ALWAYS a producer! The second organism feeds on the producer and is called a first-level

consumer. Next, a second-level consumer eats the first-level consumer. Finally, a third-level consumer may eat a second-level consumer. TREE (a PRODUCER is eaten by a)

CARPENTER ANT (a FIRST-LEVEL CONSUMER which is eaten by) a WOODPECKER (a SECOND-LEVEL CONSUMER)

Food Chains

EXAMPLE

GRASS RABBIT WOLF

Producer Herbivore Carnivore

A food chain shows only ONE possible path along which energy can move through an ecosystem.

A food web consists of many overlapping food chains in an ecosystem.

The arrows show the direction the energy is traveling.

Food Webs

ENERGY PYRAMIDWhen an organism eats, it obtains

energy.The organism uses some of this

energy to move, grow, reproduce, and carry out other life activities.

Only some of the energy obtained is available to the next organism in the food web.

An energy pyramid is a diagram that shows the amount of energy that moves from one feeding level to another in a food web.

ENERGY PYRAMID:

Carnivores Least Energy

Third-level Consumers

Carnivores

Second-level Consumers

Herbivores

First-level Consumers

Producers

Most Energy

ENERGY PYRAMIDOnly about 10% of the energy at

one level of a food web is transferred to the next higher level

The other 90% is used for the organism’s life processes

Since 90% of the energy is lost at each step, there is not enough energy to support many feeding levels in an ecosystem.

This is why there are few organisms at the highest level in a food web.

Limiting FactorsA limiting factor is an environmental

factor that causes a population to decrease.

Limiting factors include:Food & Water: If it runs out… populations

will get smaller.Space: Plants need room to grow or…

populations will get smaller.Weather: temperature & rainfall can kill

off populations or make them breed more. Hurricanes & floods can wash away nests…populations will get smaller.

Means of DispersalThe movement of organisms from one

place to another is called dispersal.Dispersal can be caused by:

Wind & Water: Wind can disperse seeds, spores of fungi, tiny spiders, and other small, light organisms.

Water transports objects that float such as coconuts and leaves which could be harboring small animals.

Other Living Things: A bird may eat berries and deposit seeds as wastes. Animals may carry sticky plant burs. Humans can also disperse organisms.

Limits to DispersalThree factors that limit dispersal of

a species:Physical barriers – water,

mountains, and deserts are hard to cross and can limit movement.

Competition – Find a unique niche or compete for resources.

Climate – the typical weather pattern in an area. Organisms stick to the area they are adapted to.

Let’s see if you can answer the EQ’s:How is life like a web?Why is it necessary for everything in

an ecosystem to work together?How do YOU fit into the larger world? How does a change in temperature

and/or precipitation affect the living things in the environment?

Why can’t there be a lone survivor?What effect does the environment

have on organisms?How does the environment affect us?