FEEDING

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FEEDING in Ecosystems
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BIG IDEA

• The niche of an organism determines that
  organisms biotic interactions with other
  organisms including its feeding relationship,
  competition, symbiosis

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Types of Feeders
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PRODUCERS

• aka autotrophs
• make their own food from inorganic molecules and
  energy

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CONSUMERS

• kinds of heterotrophs
• organisms that cannot make their own food

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CONSUMERS

• HERBIVORES
• aka primary consumers
• organisms that eat only plants
• vegetarians

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CONSUMERS

• CARNIVORES
• aka secondary or tertiary consumers
• organisms that eat herbivores
• and other carnivores
• meat eaters

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CONSUMERS

• OMNIVORES
• aka primary, secondary
• or tertiary consumers
• organisms that eats producers
• and other consumers

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CONSUMERS

• SCAVENGERS
• aka 1, 2, or 3 level consumers
• organisms that eats dead organisms
• usually does not hunt
• may eat plants or animals
• small aquatic ones often known as detritivores
  (i.e. crabs)

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DECOMPOSERS

• kinds of heterotrophs
• bacteria and fungi that consume the bodies of
  dead organism and other organic wastes

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Trophic Levels
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A TROPHIC LEVEL is a layer in the
structure of feeding relationships in an
ecosystem.
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TROPHIC LEVELS
producers 1st trophic level consumers
2nd trophic level consumers 3rd trophic
level consumers etc trophic level
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TROPHIC LEVELS
Autotrophs are the sole point of entry for new
energy into the ecosystem.
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Food Chains and Food Webs
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A FOOD CHAIN is a series of energy (food)
transfers between the trophic levels of an
ecosystem
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Food chains start with producers.
producer
primary consumer
secondary consumer
tertiary consumer
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A FOOD WEB is a network of food chains
representing the feeding relationships among the
organisms in a more complex system
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Food webs include all the food chains in an
ecosystem
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DIVERSITY STABILITY Some ecologists think that
an ecosystem with high diversity and a more
complex food web is more stable. WHY?
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WHY?

• An ecosystem with more food options will be more
  diverse because if one organism goes extinct than
  there are other options to eat.

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Biological Magnification
The increasing concentration of a pollutant in
organisms at higher trophic levels in a food web.
i.e. DDT
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Energy in the Ecosystem
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Energy enters an ecosystem when producers use
sunlight to make organic matter through
photosynthesis.
energy
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Consumers take in this energy when they eat
producers or other consumers.
energy
energy
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Most of the energy that enters through organisms
in a trophic level does not become biomass. WHY
NOT?
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Biomass
The total amount of organic matter present in a
trophic level
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10 law
only about 10 of the energy entering one trophic
level forms biomass in the next trophic level.
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Primary Production

• The synthesis and storage of organic molecules
  during the growth and reproduction of autotrophs
• - Measured as the rate of formation of new
  material per unit of the earths surface and time

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• Standing crop biomass- amount of matter found in
  a given area at any point in time
• Gross Primary Production (GPP)-refers to energy
  converted by photosynthesis

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• Net Primary Production (NPP)- refers to energy
  left over after the plant has used some of this
  chemical energy for its own metabolic needs (ex.
  Growth, reproduction)
• -plant biomass is the physical manifestation of
  NPP

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NPP
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Global NPP
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• Global NPP is the amount of energy available to
  all heterotrophs
• Turnover rates- change in standing crop biomass
  over time (low standing crop, high rate of
  production during a brief growing season)
• ex. Grasslands and oceans (surface)
• Rates of production are determined by climate
  (temp./precip.) and nutrients

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• Three hundred trout are needed to support one man
  for a year.  The trout, in turn, must consume
  90,000 frogs, that must consume 27 million 
  grasshoppers that live off of 1,000 tons of
  grass. 

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Secondary Production

• The conversion of assimilated energy into new
  tissue by heterotrophs
• -it is conceptually the same as the primary
  production or NPP of plants.

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• Organisms vary in how efficiently they can
  convert assimilated energy into secondary
  production due to widely differing metabolic
  requirements.
• Homeotherms (warm-blooded)- low net production
  efficiencies b/c they need to maintain a constant
  internal body temperature

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• Poikilotherms- organisms that do not regulate
  their temperatures internally have a higher  
  net production efficiency

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Pyramids of Biomass, Energy, and Numbers

• A pyramid of biomass is a representation of the
  amount of energy contained in biomass, at
  different trophic levels for a given point in
  time

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• pyramid of numbers- represents the number of
  organisms in each trophic level

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Bottom-Up vs. Top-Down Control

• bottom-up control, states that it is the nutrient
  supply to the primary producers that ultimately
  controls how ecosystems function
• - increase in food results in an increase in
  heterotrophs

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• top-down control, states that predation and
  grazing by higher trophic levels on lower trophic
  levels ultimately controls ecosystem function.
• - Increase in predators fewer grazes resulting
  in more producers

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Types of Teeth
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Mammals are heterodont they have different types
of teeth in their mouths. Other vertebrates are
homodont meaning they have all the same types of
teeth.
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MOLARS
PRE MOLARS
CANINES
INCISORS
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• INCISOR MODIFICATIONS
• enlargement to form chisels used for gnawing.
  i.e. rats, mice
• incisors followed by a toothless gap (diastema)
  i.e. rabbits

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What kinds of animals are these?
INCISOR
CANINE
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INCISOR
wolf
CANINE
bat
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• CANINE MODIFICATIONS
• for stabbing and holding prey
• in herbs., often reduced in size or missing
• may be weapons in displays or fighting
• in many, larger in males than in females

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• PREMOLARS
• usually, but not always, slightly smaller and
  simpler than the molars
• are deciduous, later replaced

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• MOLARS
• vary tremendously in size, shape, and function
• permanent teeth