Food chains & food webs (article) | Ecology | Khan Academy
Describe the relationship between food chains/webs and the trophic pyramid. Which organism need the greatest amount of food to survive? What is the. B(12)(C) analyze the flow of matter and energy through trophic levels using various models, including food chains, food webs, and ecological pyramids. An energy pyramid (sometimes called a trophic pyramid or an ecological in which organisms share the same function and nutritional relationship within the.
Evelyn Hutchinson and Raymond Lindeman Often, there are more producers than consumers, however, it can also be seen in many ecosystems that there are more primary consumers than producers. A "pyramid of numbers" shows graphically the population of each level in a food chain.
It is an upright pyramid given in an ecosystem, where usually the producers are more in number than any other Trophic level.
This shows the number of organisms in each trophic level without any consideration for their size. This type of pyramid can be convenient, as counting is often a simple task and can be done over the years to observe the changes in a particular ecosystem.
However, some types of organisms are difficult to count, especially when it comes to some juvenile forms. Pyramid of biomass[ edit ] A biomass pyramid shows the total mass of the organisms that each trophic level occupies in an ecosystem. Usually, producers have a higher biomass than any other trophic level, but there can be lower amounts of biomass at the bottom of the pyramid if the rate of primary production per unit biomass is very fast.
Ecological pyramid - Wikipedia
A "pyramid of biomass" shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an energy community at a particular time. It is a graphical representation of biomass total amount of living or organic matter in an ecosystem present in unit area in different tropic levels.
Typical units are grams per meter2, or calories per meter2. The pyramid of biomass may be "inverted". For example, in a pond ecosystem, the standing crop of phytoplanktonthe major producersat any given point will be lower than the mass of the heterotrophssuch as fish and insects. This is explained as the phytoplankton reproduce very quickly, but have much shorter individual lives.
One problem with biomass pyramids is that they can make a trophic level appear to contain more energy than it actually does. For example, all birds have beaks and skeletonswhich despite having mass are not typically digested by the next trophic level.
Pyramid of Energy[ edit ] A "pyramid of productivity" is often more useful, showing the production or turnover the rate at which energy or mass is transferred from one trophic level to the next of biomass at each trophic level. Instead of showing a single snapshot in time, productivity pyramids show the flow of energy through the food chain. Primary consumers are usually herbivores, plant-eaters, though they may be algae eaters or bacteria eaters.
The organisms that eat the primary consumers are called secondary consumers. Secondary consumers are generally meat-eaters—carnivores. The organisms that eat the secondary consumers are called tertiary consumers. These are carnivore-eating carnivores, like eagles or big fish.
Some food chains have additional levels, such as quaternary consumers—carnivores that eat tertiary consumers. Organisms at the very top of a food chain are called apex consumers. We can see examples of these levels in the diagram below. The green algae are primary producers that get eaten by mollusks—the primary consumers. The mollusks then become lunch for the slimy sculpin fish, a secondary consumer, which is itself eaten by a larger fish, the Chinook salmon—a tertiary consumer.
In this illustration, the bottom trophic level is green algae, which is the primary producer. The primary consumers are mollusks, or snails. The secondary consumers are small fish called slimy sculpin.
The tertiary and apex consumer is Chinook salmon. For instance, humans are omnivores that can eat both plants and animals. Decomposers One other group of consumers deserves mention, although it does not always appear in drawings of food chains. This group consists of decomposers, organisms that break down dead organic material and wastes.
Decomposers are sometimes considered their own trophic level. As a group, they eat dead matter and waste products that come from organisms at various other trophic levels; for instance, they would happily consume decaying plant matter, the body of a half-eaten squirrel, or the remains of a deceased eagle.
In a sense, the decomposer level runs parallel to the standard hierarchy of primary, secondary, and tertiary consumers. Fungi and bacteria are the key decomposers in many ecosystems; they use the chemical energy in dead matter and wastes to fuel their metabolic processes. Other decomposers are detritivores—detritus eaters or debris eaters. These are usually multicellular animals such as earthworms, crabs, slugs, or vultures.
They not only feed on dead organic matter but often fragment it as well, making it more available for bacterial or fungal decomposers.
trophic pyramid | Definition & Examples | egauteng.info
When they break down dead material and wastes, they release nutrients that can be recycled and used as building blocks by primary producers.
Food webs Food chains give us a clear-cut picture of who eats whom. However, some problems come up when we try and use them to describe whole ecological communities.
For instance, an organism can sometimes eat multiple types of prey or be eaten by multiple predators, including ones at different trophic levels.
This is what happens when you eat a hamburger patty! The cow is a primary consumer, and the lettuce leaf on the patty is a primary producer. To represent these relationships more accurately, we can use a food web, a graph that shows all the trophic—eating-related—interactions between various species in an ecosystem.
The diagram below shows an example of a food web from Lake Ontario. Primary producers are marked in green, primary consumers in orange, secondary consumers in blue, and tertiary consumers in purple. The bottom level of the illustration shows primary producers, which include diatoms, green algae, blue-green algae, flagellates, and rotifers.
The next level includes the primary consumers that eat primary producers. These include calanoids, waterfleas, cyclopoids, rotifers and amphipods.