Food and Energy: Energy Transfer and Ecological Pyramids

Edited by Jamie (ScienceAid Editor), Jen Moreau, Carlos Spicy Wiener, SarMal and 2 others

You've probably studied food chains since primary school and are familiar enough with the concept to differentiate between herbivores and carnivores to identify those species at the top of the food chain and those species on the bottom. These concepts are the rudimentary basics of the food chain, however, food chains can be much more intricate and are undoubtedly vital parts of our ecosystems. As the name implies, food chains link the consumption of food, the amount of energy wasted and the transfer of energy amongst a species. Food chains always start with a plant source and always end with an animal. A simple example of a food chain would be: a plant is consumed by a herbivore, the herbivore is then consumed by a carnivore. Seems pretty simple right? It is, but there are many more links and transference of energy depending on the food chain.

Was this helpful? Yes | No | I need help
biology ecology food.html 71878.jpg

Ad

Food Chains

A typical food chain looks like this:

a food chain involving grass, a rabbit and fox

A food chain the transference of energy between organisms through consumption, in this case, the rabbit is eating grass and the fox is eating the rabbit.

The initial energy source is found in the plant. The plant uses initial energy from the sun to convert into chemical energy via photosynthesis. The herbivores eat the plants, ingesting some of the energy from the plant of the energy. The herbivore then becomes prey their energy is transferred to the predator.

Was this helpful? Yes | No | I need help

When consumed some of the energy is transferred but some of the energy is lost at each link in the chair (or trophic level). In the above example, the grass loses some energy by respiration, the rabbit loses energy by heat and waste. By the time the energy is transferred to the fox, there is only a fraction of the total energy transferred.

Was this helpful? Yes | No | I need help

Energy Transfer

In each ecosystem, it is energy, that enables organisms to live. This energy mainly comes from one original source: photosynthesis. The plants in the ecosystem use this solar energy to produce carbohydrates which are then consumed by other organisms: transferring the energy.

Was this helpful? Yes | No | I need help

Not all of the energy from sunlight, however, is used by the plants solely as energy; they are far from efficient. A lot of sunlight misses the plant, is in the wrong wavelength or lost in the inefficiencies of photosynthesis. We use the term gross primary production to refer to the total energy in the molecules of the plant; net primary production is the surplus energy not used by the plant itself.

Was this helpful? Yes | No | I need help

At each level of the food chain energy is lost because it is used by the organism itself for respiration. This limits the number of steps there can be in a food chain.

diagram representing energy transfer in a food chain

The diagram above represents quantitatively (in numbers) the efficiency of energy transfer in a food chain. Notice that only about 8% of the energy is transferred from one stage to the next.

Ecological Pyramids

A food chain is represented quantitatively (with numbers) in the form of a pyramid of number. Listed below is a quantitative representation of the previously presented food chain. From this graph, we can see there are fewer foxes than rabbits; which makes sense because a fox must eat several rabbits to get enough energy in order to survive.

Was this helpful? Yes | No | I need help

An ecological pyramid shows the relative sizes of different components at the various trophic levels of a food chain. A trophic level refers to each stage (shown as a horizontal bar on ecological pyramids). There are three types of ecological pyramid we use: numbers, biomass and energy.

Was this helpful? Yes | No | I need help

pyramids of energy, biomass, and numbers for two different food chains

The pyramids of numbers show the raw number of each species at each trophic level. The top example is a typical food chain with a large number of producers but diminishing numbers of consumers. However, if the producer was a tree, followed by insects, then the bottom bar would appear small as many organisms feed on one tree. In this instance, the pyramid of biomass is more useful as the tree is much larger.

Was this helpful? Yes | No | I need help

In the lower example, both the pyramid of numbers and biomass show a smaller producer bar; given what was discussed under the previous heading - this does not make sense. This is because the phytoplankton reproduces very quickly. However, when we represent this information in a pyramid of energy we get a true pyramid.

Was this helpful? Yes | No | I need help

Plotting the energy will always give a true pyramid because it is impossible to create new energy. A trophic level will always be smaller than the one below it.

The picture of grass in the first graphic was taken by Catarina Carvalho and taken from wikimedia commons

Questions and Answers

How does energy transfer through the number, energy, and biomass pyramids?

How does the energy transfer through all these pyramids. The article dossn't say how energy transfer through number, energy, and biomass pyramids

ScienceAid QnA. This section is not written yet. Want to join in? Click EDIT to write this answer.

Why is the energy conversion factor different for caterpillar (5.5 kcal/g) vs. the food (4.35 kcal/g)?

I had to calculate the energy for both the caterpillar and food in my experiment

ScienceAid QnA. This section is not written yet. Want to join in? Click EDIT to write this answer.

Referencing this Article

If you need to reference this article in your work, you can copy-paste the following depending on your required format:

APA (American Psychological Association)
Food and Energy: Energy Transfer and Ecological Pyramids. (2017). In ScienceAid. Retrieved Apr 29, 2017, from https://scienceaid.net/biology/ecology/food.html

Was this helpful? Yes | No | I need help

MLA (Modern Language Association) "Food and Energy: Energy Transfer and Ecological Pyramids." ScienceAid, scienceaid.net/biology/ecology/food.html Accessed 29 Apr 2017.

Chicago / Turabian ScienceAid.net. "Food and Energy: Energy Transfer and Ecological Pyramids." Accessed Apr 29, 2017. https://scienceaid.net/biology/ecology/food.html.

If you have problems with any of the steps in this article, please ask a question for more help, or post in the comments section below.

Comments

ScienceAid welcomes all comments. If you do not want to be anonymous, register or log in. It is free.

Ask the author

Jamie
Featured Author
166 Articles Started
1,284 Article Edits
43,715 Points
Jamie is a featured author with ScienceAid. Jamie has achieved the level of "Captain" with 43,715 points. Jamie has started 166 articles (including this one) and has also made 1,284 article edits. 105,000 people have read Jamie's article contributions.
Jamie's Message Board
Jamie: Hi, my name is Jamie.
Jamie: Can I help you with your problem about "Food and Energy: Energy Transfer and Ecological Pyramids"?
 

Article Info

Categories : Ecology

Recent edits by: Sharingknowledge, SarMal, Carlos Spicy Wiener

Share this Article:

Thanks to all authors for creating a page that has been read 3,697 times.

Do you have a question not answered in this article?
Click here to ask one of the writers of this article
x

Thank Our Volunteer Authors.

Would you like to give back to the community by fixing a spelling mistake? Yes | No