Post on 29-Dec-2015
transcript
Food Webs
Review
• Food chains represent flows of matter and energy
• They are always pyramid shaped
Energy Flow in Ecosystems
• Three things can happen to the energy taken in by the organisms in a trophic level:– It can be passed on to the next trophic level in the food
chain when the organism is eaten. – It can become stored in detritus. This energy is passed
on to decomposers when the detritus decays. – It can be converted to heat energy by inefficient
chemical reactions, radiated by warm bodies, or in friction due to movement. The heat energy is lost to the surroundings, and cannot be regained by living organisms.
Grazer Food Chains .
• Begins with plants
Grazer Food Chains
Detritus Food Chain .
• Begins with dead material or waste
Detritus Food Web• numbers are very high• organisms are small• don’t move a lot• consume organic wastes• releasing a great deal of
energy mostly as heat • converting it back into its
inorganic nutrient form
algae, bacteria, slime molds, fungi, protozoa, insects, mites, crustaceans, centipedes, mollusks
Detritus Food Web
• By far the most important food web in a forest.– Not much is removed
from the forest, nutrients are recycled.
Detritus Food Web• Detritus food chains are connected to a
grazing food chain when consumers of a grazing food chain feed on the decomposers of the detrital food chain
• In some ecosystems, less than 1% of energy may move through the grazing food web while over 99% moves through the detritus food web
Food Webs
Pond Food Web
Land Food Web
Marine Food Web
Pond Food Web