Who eats who!!!!! Help!!!

Dr. B. K. Bindhani

BY

FOOD CHAINS

• The producers, consumers, and decomposers of each ecosystem make up a food chain.

• There are many food chains in an ecosystem.

• Food chains show where energy is transferred and not who eats who.

All Food Chains and Webs start with the sun. The sun is the source of all the

energy on the earth.

Plants are producers. They turn energy from the sun into sugars that

animals can use.

Another Link in the Food Chain

Everyone plays a specific role in the food chain of life. You might be a human thinking they are king of the hill or you might be a bacterium under the feet. You are very important to the survival of the system no matter what role you play.

Food Chains and Webs You will see the terms food chains and food webs. They describe the same series of events that happen when one organism consumes another to survive.

Food web is a more accurate term since every organism is

involved with several other organisms.

The Producers

Producers are the beginning of a simple food chain. Producers are plants and vegetables.

The Consumers

Consumers are the next link in a food chain. There are three levels of

consumers.

•Tertiary consumers (3rd order) –Eat the primary and secondary consumers (CARNIVORES) ex: wolf eats cat and squirrel

•Secondary consumers (2nd Order) –Eat the primary consumers (CARNIVORES) example: cat eats squirrel

•Primary consumers (1st Order) –Worms, insects, squirrels, mice: all eat plants (HERBIVORES) ex: squirrel eats acorns

Insects and other animals eat plants for energy. They are primary

consumers. They are herbivores.

Secondary consumers are animals that eat other animals for energy. They are

called carnivores.

Omnivores eat both plants and meat

–They can be EITHER primary or secondary consumers.

Scavengers =They eat the remains of dead organisms left by the consumers - vultures, coyotes, hyenas

The last links in the chain are the decomposers. (They break things down) Like bacteria, mold, fungi, mushrooms

•If you die, they eat you. •If you poop, they eat that. •If you lose a leaf, they eat it.

Whenever something that was alive dies, the decomposers get it.

The Decomposers

Decomposers are organisms that eat dead things for energy.

Decomposers break down nutrients in the dead "stuff" and return it to the soil.

The producers can then use the nutrients and elements once it's in the soil.

The decomposers complete the system, returning essential molecules to the producers.

• Together, these groups make up a FOOD CHAIN • E.g., grass, rabbit, eagle

Carnivore Herbivore Producer

Carnivores • Carnivores can be further

divided into groups:

• quaternary carnivore (top)

• tertiary carnivore • secondary carnivore • primary carnivore

• The last carnivore in a

chain, which is not usually eaten by any other carnivore, is often referred to as the top carnivore.

EXAMPLE OF A FOOD CHAIN

Food chains

FOOD CHAINS

Problems

• Too simplistic • No detritivores

• Chains too long

PROBLEMS

• Rarely are things as simple as grass, rabbit, hawk, or indeed any simple linear sequence of organisms.

• More typically, there are multiple interactions, so that we end up with a FOOD WEB.

TROPHIC LEVELS • A trophic level is the position occupied by an

organism in a food chain. • Trophic levels can be analyzed on an energy

pyramid. • Producers are found at the base of the pyramid

and compromise the first trophic level. • Primary consumers make up the second trophic

level. • Secondary consumers make up the third trophic

level. • Finally tertiary consumers make up the top

trophic level.

Modified from: General Ecology, by David T. Krome

Trophic level: All the organisms that are the same number of food-chain steps from the primary source of energy

TROPHIC LEVELS FOUND ON AN ENERGY PYRAMID

• The greatest amount of energy is found at the base of the pyramid.

• The least amount of energy is found at top of the pyramid.

TROPHIC STRUCTURE REMINDER

• Eltonian pyramids. • Number of individuals per species. • Are this pyramid stable?

TROPHIC STRUCTURE REMINDER

• What if we transformed each species into biomass instead of absolute numbers?

BIOMASS

• Energy is sometimes considered in terms of biomass, the mass of all the organisms and organic material in an area.

• There is more biomass at the trophic level of producers and fewer at the trophic level of tertiary consumers. (There are more plants on Earth than there are animals.)

• Bio=life Mass=weight • Bio + Mass = Weight of living things within an

ecosystem.

FOOD WEBS • All the food chains in an area make up the food web of

the area.

FOOD WEB OF A HOT SPRING

FOOD WEB OF THE HARP SEAL

Summary

• Combined food chains make food webs. • Food webs start with the sun • Food webs contain producers, consumers,

and decomposers. • We are part of the food web, too!

ENERGY FLOW IN ECOSYSTEMS

• All organisms require energy, for growth, maintenance, reproduction, locomotion, etc.

• Hence, for all organisms there must be: A source of energy

A loss of usable energy

Energy flow • Simplistically:

• This pattern of energy flow among different organisms is the TROPHIC STRUCTURE of an ecosystem.

HEAT

Producers Consumers

Decomposers

HEAT

TERMINOLOGY OF TROPHIC LEVELS

• We can further separate the TROPHIC LEVELS, particularly the Consumers:

• Producers (Plants, algae, cyanobacteria; some chemotrophs)--capture energy, produce complex organic compounds

• Primary consumers--feed on producers

• Secondary consumers--feed on primary consumers

• Tertiary consumers--feed on secondary consumers

MORE TROPHIC LEVELS:

• Detritivores--invertebrates that feed on organic wastes and dead organisms (detritus) from all trophic levels.

• Decomposers--bacteria and fungi that break down dead material into inorganic materials.

ALTERNATE TERMINOLOGY • Producers = Plants etc. that capture energy from

the sun.

• Herbivores = plant-eaters. • Carnivores = animal-eaters.

• Omnivores--eat both animals and plants.

• Specialized herbivores: • Granivores--seed-eaters. • Frugivores--fruit-eaters.

TYPES OF ENERGY

• Heat Energy

• Mechanical Energy (+gravitational energy, etc.)

• Chemical Energy = energy stored in molecular bonds

PRIMARY PRODUCTIVITY

• Primary productivity is the rate of energy capture by producers.

• = the amount of new biomass of producers, per unit time and space

• Gross primary production (GPP) = total amount of energy captured

• Net primary production (NPP) = GPP - respiration

• Net primary production is thus the amount of energy stored by the producers and potentially available to consumers and decomposers.

• Secondary productivity is the rate of production of new biomass by consumers, i.e., the rate at which consumers convert organic material into new biomass of consumers.

• Note that secondary production simply involves the repackaging of energy previously captured by producers--no additional energy is introduced into the food chain.

• And, since there are multiple levels of consumers and no new energy is being captured and introduced into the system, the modifiers gross and net are not very appropriate and are not usually used.

TRANSFORMATIONS OF ENERGY

• How is solar energy converted to chemical energy?

• How does this process influence life as we see it on earth?

• The transformations of energy from solar radiation to chemical energy and mechanical energy and finally back to heat are a traditional topic of Ecosystem Ecology.

AN ECOSYSTEM HAS ABIOTIC AND BIOTIC COMPONENTS:

• ABIOTIC components:

• Solar energy provides practically all the energy for ecosystems.

• Inorganic substances, e.g., sulfur, boron, tend to cycle through ecosystems.

• Organic compounds, such as proteins, carbohydrates, lipids, and other complex molecules, form a link between biotic and abiotic components of the system.

• BIOTIC components: • The biotic components of an ecosystem can be

classified according to their mode of energy acquisition.

• In this type of classification, there are:

Autotrophs and Heterotrophs

AUTOTROPHS • Autotrophs (=self-nourishing) are called

primary producers.

• Photoautotrophs fix energy from the sun and store it in complex organic compounds

• (= green plants, algae, some bacteria)

photoautotrophs simple inorganic compounds

complex organic compounds

light

• Chemoautotrophs (chemosynthesizers) are bacteria . - That oxidize reduced inorganic substances.

- Typically sulfur and ammonia compounds. and - Produce complex organic compounds.

chemoautotrophs reduced inorganic compounds

complex organic compounds

oxygen

CHEMOSYNTHESIS NEAR HYDROTHERMAL VENTS

OTHER CHEMOAUTOTROPHS: NITRIFYING BACTERIA IN THE SOIL UNDER OUR FEET!

HETEROTROPHS • Heterotrophs (=other-nourishing) cannot

produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. HETEROTROPHS

SIMPLE INORGANIC

COMPOUNDS

COMPLEX ORGANIC

COMPOUNDS

(this may include several steps, with several different types of organisms)

HEAT

• Heterotrophs can be grouped as: • Consumers.

• Decomposers.

• Consumers feed on organisms or particulate organic matter.

• Decomposers utilize complex compounds in dead protoplasm.

• Bacteria and fungi are the main groups of decomposers.

• Bacteria are the main feeders on animal material.

• Fungi feed primarily on plants, although bacteria also are important in some plant decomposition processes.

ECOLOGICAL PYRAMIDS • The standing crop, productivity, number of

organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain.

• Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem.

producers herbivores carnivores

PYRAMID OF ENERGY

• A pyramid of energy depicts the energy flow, or productivity, of each trophic level.

• Due to the Laws of Thermodynamics, each higher level must be smaller than lower levels, due to loss of some energy as heat (via respiration) within each level.

producers herbivores carnivores

Energy flow in :

PYRAMID OF NUMBERS • A pyramid of numbers indicates the number of

individuals in each trophic level. • Since the size of individuals may vary widely and may not

indicate the productivity of that individual, pyramids of numbers say little or nothing about the amount of energy moving through the ecosystem.

# of producers # of herbivores # of carnivores

PYRAMID OF STANDING CROP

• A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time.

• As for pyramids of numbers, a pyramid of standing crop may not well reflect the flow of energy through the system, due to different sizes and growth rates of organisms.

biomass of producers biomass of herbivores biomass of carnivores

(at one point in time)

INVERTED PYRAMIDS • A pyramid of standing crop (or of numbers) may

be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level.

• This can occur if the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated.

biomass of producers biomass of herbivores biomass of carnivores

(at one point in time)

PYRAMID OF YEARLY BIOMASS PRODUCTION

• If the biomass produced by a trophic level is summed over a year (or the appropriate complete cycle period), then the pyramid of total biomass produced must resemble the pyramid of energy flow, since biomass can be equated to energy.

producers

herbivores

carnivores

Yearly biomass production (or energy flow) of: