Food Web notes

Autotrophs Organisms that can use the energy in sunlight to convert water & CO2 into food via photosynthesis. Also called Producers b/c they produce all of the food that heterotrophs use. Ex. Plants, Algae, & some bacteria

Autotrophs

Autotrophs Chemotrophs Autotrophs that convert chemicals into energy via chemosynthesis. Ex. Bacteria

Heterotrophs Organisms that do not make their own food Also called Consumers b/c they consume other organisms in order to live. Ex. All animals, Mushrooms

Heterotrophs

Heterotrophs Consumers 1. Detrivores (Scavengers) – feed on the tissue of dead organisms Ex. – Crabs, Shrimp, etc.

Heterotrophs Consumers 2. Herbivores – eat only plants Ex. – Krill, Parrotfish 3. Carnivores – eat only meat Ex. – Sharks, Seals

Heterotrophs Consumers plants & animals Ex. – Sea Otters, Humans 4. Omnivores – eat both plants & animals Ex. – Sea Otters, Humans 5. Decomposers – absorb dead material & break it down into nutrients Ex. – Bacteria

Trophic levels Energy moves from one organism to another when it’s eaten. Each step in this transfer of energy is a trophic level.

Transfer of energy Energy is neither created nor destroyed, it just changes forms. Only 10% of the energy from each level is transferred to the biomass of the next level. The rest is used up in daily living. Biomass - the total mass of the organic matter

The 10% rule

Food chains Energy flow from one trophic level to the next. Involves only one organism at each trophic level. Primary Consumers – eat autotrophs (producers) Secondary Consumers – eat primary consumers Tertiary Consumers – eat secondary consumers Decomposers – break down dead organisms

Food chains Notice that the arrow points in the direction of the energy transfer, NOT “what ate what”

Food webs Most organisms eat more than JUST one organism. Food webs are more complex & show many organisms.

Trophic pyramids Shows the relationship between organisms in an ecosystem & which level has the most energy & the highest # of organisms.

Trophic pyramids Which level has the most energy? the bottom level Which level has the most organisms? Which level has the least organisms? Which level has the least energy? the bottom level the bottom level the top level the top level