Unit 1 - Ecology - Food Relationships

amount of energy that is transferred to the next trophic level

10% (90% is lost) As you move up a food chain/web/pyramid, the amount of energy is only 10% of the level before.

secondary consumer

A consumer that feeds off of primary consumers.

primary consumer

A consumer that feeds off of producers (an herbivore).

tertiary consumer

A consumer that feeds off of secondary consumers.

food web

A diagram that shows the flow of energy from prey to predator in many directions.

food chain

A diagram that shows the flow of energy from prey to predator in one direction only.

biomass pyramid

A pyramid that shows the amount of biomass in a food chain. Each level has less mass than the level below so producers have the most biomass, the top consumer has the least.

energy pyramid

A pyramid that shows the amount of energy in a food chain. Each level has less energy than the one below it. Since producers are at the bottom, they have the most energy.

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected (+/0)

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed (+/-)

Mutualism

A relationship between two species in which both species benefit (+/+)

Symbiosis

A relationship in which two different organisms live in close association with each other. Three types: mutualism, parasitism, commensalism.

Keystone species

A species on which other species in an ecosystem largely depend, if it were removed the ecosystem would change drastically. EX) beaver, coral polyps

biomass

Amount of mass (weight) in a living organism.

scavenger

An animal that only eats other dead animals. Example: crows and hyenas.

decomposer

An organism that eats any dead organism. Examples: bacteria, fungi and worms.

producer (autotroph)

An organism that gets food from photosynthesis using the sunlight like plants and algae.

parasite

An organism that lives on or inside another organism organism and causes it harm by using it for food (eating skin cells, sucking it's blood or living in it's digestive system stealing it's food). Example: lice, leeches, tapeworms and fleas are all parasites.

consumer (heterotroph)

An organism that must consume (eat) it's food like dogs, cats, human, insects, fungi, protists.

herbivore

Animals that only eat plants. Examples: rabbits or deer

Why are there always more prey than predators?

Because 1 predator will consume many prey to stay alive. You will have to feed 1 snake at least 100 mice to keep it alive.

Why does the amount of energy and biomass decrease as you move up a food chain or pyramid?

Because not all the energy or mass consumed by the predator is turned into new body parts. Most is used to do life functions to keep the organism alive.

Which organisms feeds on every member of a food chain or a food web?

Decomposers. They eat everything that dies and return their nutrients back to the soil for plants to use to grow.

trophic level

Each step in a food chain, food web, or pyramid

omnivore

Organisms that eat both plant and animal. Examples: human

predator

Organisms that hunt and eat their prey. They are a type of consumer (a heterotoph).

carnivore

Organisms that only eat meat from other animals. Example: lion, wolf

The arrows in a food chain always point towards the organism that is the

Predator - the organism that is eating. The arrow points where the energy is going. Energy from the prey (grasshopper) goes into the predator (shrew).

host

The organism being harmed by the parasite lives on or inside of it. Example: The parasitic flea lives on the dogs skin and eats the dog's blood. The dog is the host because it is being harmed.

prey

The organism that is hunted and eaten by the predator - they are the food, they die.

Why do invasive species become such a problem in their new ecosystem?

outcompete native species, no natural predators, usually unlimited or very large food supply

invasive species

species that enter new ecosystems and multiply, harming native species and their habitats

Food webs with more biodiversity (differences) are more

stable (they don't change) because there are many food choices for each predator.

Food webs with less biodiversity (differences) are more

unstable (changing) because there are not a lot of food choices for each predator so if their food source dies, there is nothing else in the area they can eat.