J. Quigley

2012

Everything that organisms do require energy. Running, breathing, and even sleeping! Every species must somehow get food for energy.

Grass grows by making energy from the sun, a zebra eats grass in the savanna, a lion eats the zebra and the lion eventually dies and is eaten by scavengers. The rest of the lions carcass is decomposed by bacteria and fungus.

At each step in this process, energy flows through the ecosystem

An organism eating another organism is the most obvious interaction in a community. This interaction transfers energy through an ecosystem.

Each level of energy transfer is a trophic level

The primary source of energy in an ecosystem is the sun.

Photosynthetic organisms make their energy from the sun and are called producers Plants, trees,

grasses, herbs, fruits, vegetables, nuts, berries…

Are organisms that eat producers.

They are called herbivores

“Herb” means plant and “vore” means eatingCow, horse,

rhinoceros, zebra, rabbit, squirrel…

A secondary consumer eats primary consumers

They are called carnivores

“Carni” means meat and “vore” means eatingWolf, lion, shark,

owl, cats…

These organisms eat dead things.Scavengers eat

the meat off of a dead carcass Vultures, small

carnivores like coyotes, hyenas…

Decomposers recycle or break down the remains of a dead organism Bacteria and fungus

In an ecosystem the energy flows from the sun to the primary consumers to the secondary consumers to the scavengers and decomposers.

The energy flow through organisms in an ecosystem

Example: Nuts give energy to a squirrel who gives energy

to a fox, when the fox dies it gives energy to a vulture and bacteria.

In most ecosystems energy does not follow a simple food chain. Energy flow is much more complicated. Most organisms eat more than one kind of food…

A food web is many food chains put together

Energy is stored at each link in a food web. But some energy that is used is lost as heat into the environment and is not recycled.

10% rule… When a zebra eats 20 pounds of grass 18 pounds are used for the zebra to run, mate, play, find more food, walk, sleep, make babies…only 2 pounds stay with the zebra and are available to the next trophic level

If a human eats a large fish in the 3rd trophic level it takes 1000kg of producers to make a 1gk human

If a human eats a cow in the 2nd trophic level, it takes 100kg of producers to make a 1kg human

If a human eats producers, it only takes 10kg of producers to make a 1kg human…

Hmmm… maybe we should all eat more producers and it will help fight starvation all over the world and protect the environment!!!

A triangular diagram that shows an ecosystem’s loss of energy, which results as energy passes through the ecosystems food chain

The bottom is the lowest trophic level, has the most energy and is made from producers

The middle layer is made of herbivores (primary consumers) and has less energy than the bottom

The top layer is made of carnivores (secondary consumers) and contains the least amount of energy