Talk:Food web/Archive 2

Archive 1

Archive 2

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 22 January 2019 and 24 May 2019. Further details are available on the course page. Student editor(s): Wcchristoph2.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 21:37, 16 January 2022 (UTC)

Subpages

• Section headers

Here to help

I've been working on ecology for a number of years. I have decided to make this my next project page and have started by putting a better definition in the lead to distinguish food webs from food chains. I'm an ecologist by training - with a MSc in Zoology and I'm completing my MEd in ecoliteracy education. Expect some major revisions in the next few months.Thompsma (talk) 01:49, 10 June 2011 (UTC)

Requested move

I'm would like to put out a vote to move this to food web. I have read the archived debate and believe that food web is the appropriate title. The number of search hits for food chain is irrelevant. A food chain is contained within a food web. The reason for a greater number of citation hits for food chain is due to the mathematics in this scientific branch. People who study food webs are interested in food chain length - an important statistic when comparing different ecosystems. Charles Elton was the first to come up with the idea in 1927 and said it this way:

• "There are, in fact, chains of animals linked together by food, and all dependent in the long run upon plants. We refer to these as 'food-chains,' and to all the food-chains in a community as the 'food-cycle.'"[1]

Food cycle later became known as a food web. Here are the logical choices as I see it:

• create three separate pages: trophic dynamics, food web, food chain
• create two separate pages: trophic dynamics and food web (with food chain described within)

The three separate pages seems a little drastic. I'm comfortable with accommodating food chain into food web.18:27, 10 June 2011 (UTC)

I've done a bit of work in here and nobody is leaving any comments about the proposed name change. I read AjaxSmack comments above and have two things in response. 1) Food chain is not the common name (WP:UCN) - it is contained within a food web. It has a real scientific definition even if people think that they mean the same thing - they do not. 2) The question was asked - "What does "'food web' is broader" mean?" - response: It means that a food web describes the entire community of connections, whereas a food chain describes direct connections from one node to another - like a dot-to-dot illustration.

Given the recent modifications and the lack of discussion in here - I will give this another week or so, but I'm getting the urge to modify this to food web, which seems like the correct thing to do.Thompsma (talk) 15:57, 13 June 2011 (UTC)

I agree entirely with the move to food web, which I originally proposed above, and also with your merging trophic dynamics into food web, Thompsma. Perhaps there could be a separate article on food chain, which just briefly describes how chains are related to webs, as components within a web, or describes a web as a network of chains. --Epipelagic (talk) 23:26, 13 June 2011 (UTC)

I think this article should first be completed before a main article on food chain is created. In order to understand food chains - a complete comprehension of food webs is necessary. I posted a speedy delete on trophic dynamics and copied the text to here. It is a rag-tag bunch of information at this point - but I will be going through here with a fine toothed comb to get it straightened out. What a mess!!Thompsma (talk) 23:29, 13 June 2011 (UTC)

Major revisions and formatting

Okay...I just did a major clean-up on this article. It still needs a lot of work, but I have a basic format set out. The network of articles was a mess and I had to create a few new ones - mineral cycle and mineral nutrients. I tried not to delete text that had previously been cited, but the citations that I kept need to be properly formatted - if anyone would like to work on these sorts of editorial things - this would be awesome! Please try to keep everything consistent so that we can eventually get this to featured article status.Thompsma (talk) 02:11, 14 June 2011 (UTC)

Sub-heading proposals

This discussion has been moved to this subpage

Created food chain

I created the separate article for food chain last night. It is a stub. Food chain is the more advanced topic and it first requires an understanding of food webs. This article was a mix-match of ideas - mostly pertaining to food webs when I got here. It was a bit of a convoluted process to get this renamed to food web and in retrospect I could have done it a bit different. Anyway, the process is under way. I have posted citations that can mostly be accessed freely online that describe what these things are and will continue to work away to get the ecology sections in better shape. Hoping more people will start to gravitate to these topic areas.Thompsma (talk) 15:39, 14 June 2011 (UTC)

Is there a need for trophic dynamics article?

I spent the time cleaning up, deleting, and re-threaded the links in these ecology related pages in an attempt to bring things to order - because there was a complete chaos. Much work still needs to be done, but I think a page on Trophic Dynamics may be justified - but I'm not certain about this. Trophic level is written well and it is comprehensive. Trophic species is a stub I created yesterday. However, an article that links or synthesizes food webs, food chains, trophic species, and trophic levels may be helpful, but it would have to be done in such a way that it doesn't duplicate what is being stated in these other articles (which is what was originally happening). In many respects, however, a food web broadly covers the very same topics as trophic dynamics does. Elton (1927)[2] initiated the food cycle (web) and food chain system of analysis and Lindeman's (1942) classic paper[3] brought these ideas together to initiate the science of trophic dynamics sorting trophic species into trophic levels. However, trophic species and trophic levels occur in food webs - so is a trophic dynamics article needed? I'm conflicted on this one and I'm leaning toward a sub-heading on trophic dynamics in this main article and leaving it at that. Thoughts??Thompsma (talk) 19:03, 14 June 2011 (UTC)

I agree with you, a section clarifying trophic dynamics in relation to food webs is enough for now. It can be easily split as a separate article anytime. I wrote the article on trophic level, and have looked from afar at the rest of the mess here for some time. I'm happy to assist and let you take the lead Thompsma, since you seem to work best that way. Would you like me to solicit help from related projects? --Epipelagic (talk) 00:18, 15 June 2011 (UTC)

Thanks for your input Epipelagic! Any help you can provide would be greatly appreciated - feel free to comment on edits or structure.Thompsma (talk) 03:24, 15 June 2011 (UTC)

Okay. I've reformatted this page so it is better suited for collaboration. I archived the earlier material, added a "subpages" section at the top of the page, and moved the discussion on section headers to its own subpage. I also asked a number of biology themed projects for help. --Epipelagic (talk) 06:25, 15 June 2011 (UTC)

Comments for FA effort

Hi, I saw the request here and at other WikiProjects. This is not my usual territory (I've got several animal phyla to GA, and am working in jumping spider species and genera). However, I may be help with comments. I'll start from the top, although in principle the lead should be improved last, after the body of the article is stable:

Lead

• It's too technical, while a lead should draw in general readers, and the article should introduce more technical phrasing gradually and sparingly. --Philcha (talk) 10:06, 15 June 2011 (UTC)
• The lead sentence is too technical: "... is a heuristic concept map that depicts trophic (feeding) connections (who eats whom) in an ecological community". "Heuristic" is Greek (literally) to readers, and adds no value here. "Concept map" is another example, and the w-linked article looks based on object-based programming, which will confuse readers who are not acquainted with both ecology and programming. Etc. ... How about e.g. "A food web (or food cycle) describes who eats whom in organisms that interact with each other." --Philcha (talk) 10:06, 15 June 2011 (UTC)

I took a quick look and will be simplifying as I go along. It is technical at this point - well aware of this. I'm slowly organizing things in the article and trying to get the scaffold ready so that the lead can be simplified. Your description is probably better for the lead, but for now I am flushing out the ideas for the main body of text. In future it might be worth while to go the way of the evolution article and create an introductory article - introduction to evolution. I agree with you - but the bigger problem is not technical, it is structural.Thompsma (talk) 18:56, 15 June 2011 (UTC)

• "top predators (species that are not eaten by any others in the web)" is misleading, as top predators die and are scavenged. I can't think of a simple way of avoiding this. So I'd start with the other end of the simplest cycle (autotrophs), work "upward", and then add the "inner" / "nested" cycles of scavenging. Not in the lead, I think, but in the body of article, you should summarise the carbon cycle, as food webs "leak" and the carbon cycle very slowly recycles carbon and other elements needed for building organisms, e.g. iron, silicon, sulphur, phosphorus. Back to the lead, how about e.g. "Primary producers such as bacteria and plants build organic components from inorganic substances such as minerals and gases. At the next level, primary producers are eaten by other organisms such as filter feeders and herbivores. A few levels up are the top predators such as crocodiles, lions and sperm whales, which mainly live by eating other animals until they usually die of accidents or old age. Such a one-way path up the levels is called a food chain. At all levels dead organisms are recycled by scavengers, ranging from bacteria and fungi to vultures and some deep sea sharks." --Philcha (talk) 10:06, 15 June 2011 (UTC)

Of course, but that definition of top predators comes directly from the peer-reviewed papers of Stuart Pimm (who wrote the book on food webs[4]). See: "Top predators are species on which nothing else in the web feeds, basal species feed on nothing within the web, and intermediate species have both predators and prey within the web."[5]. This also requires an understanding of a trophic species and the way that ecologists categorize things in trophic studies - Hairston & Hairston (1993)[6] helps to describe the scientific reasoning behind complexity in trophic precision vs. sloppy boundaries in real nature. Polis and others have even argued that there is no such thing as a trophic level - "We reiterate that the notion that species clearly aggregate into discrete, homogeneous trophic levels is fiction."[7]. This issue was addressed by Hariston (among others). Nobody disagrees with Polis and others on this point - there is no clear aggregate - but what ecologists are interested in are the main energy pathways and general mathematical principals that can be understood from this. The literature on this discussion is extensive. Moreover, technically - eaten and decomposed are not the same thing. The metaphors of science and language can and do complicate things. I had the same issue when I read Pimm's definition and he used the term feeds - I switched to eaten, because a saprophyte digests in decomposition, possibly feeds, but I think eat (and what Pimm is getting at) connotes a certain level of targeted tactic. Saprophytes digest whatever may fall - whereas a top predator has specific adaptations and search strategies to target certain prey items. I understand your confusion and will try to sort this out in time.Thompsma (talk) 16:18, 15 June 2011 (UTC)

• "The number of transfers of food and energy from the basal species (e.g., plants, detrivores, or saprophyte) in a food web to the apex predator provides a measure of food chain length and food web structure" uses unnecessarily complex phrasing, and assumes the idea of energy without explaining it. How about e.g. "All these transformations of matter require energy, mainly from the sun by photosynthesis, and also by deep sea seeps which are driven by the Earth's internal heat and support local ecosystems based on bacteria. The number of transfers of food and energy from the basalbottom-level species to the top predators provides a measure of food chain length and food web structure." --Philcha (talk) 10:06, 15 June 2011 (UTC)

At this point the definition of a food chain was the problem with this article to begin with. Let's first work on the body of the text and avoid debates about the lead. It is a technical definition for now - it is precise in its meaning, and once we have worked out the rest of this article in its structure I think we can address these kinds of concerns. I agree with you that this is a problem - but now is not the time to nit pick on the little details. This article first needs a global structure before the finer issues are critiqued.Thompsma (talk) 16:18, 15 June 2011 (UTC)

• Avoid "basal" in the lead and, if used in the article body, explanation how it is used in this context - I'm more acquainted with "basal" in phylogeny, for all I know there may be other uses, so it's ambiguous. --Philcha (talk) 10:06, 15 June 2011 (UTC)

Basal species is a very common term in food web literature:

• "This feature together with fewer noxious compounds (Porter 1977) make some algal plankton (naked green algae, nanoflagellates , crysophytes, dinoflagellates, and certain diatoms) unusually vulnerable and nutritious to herbivores; these are the basal species of the aquatic trophic cascades."[8]
• "The perturbation to the system will return to l/e of its initial value in a time that is the return time multiplied by the time it takes the basal species to produce one new individual."[9]
• "While models of complex food webs implicitly incorporate exploitative competition among most species, they generally ignore any form of resource competition among the basal species."[10]
• "Species types1±8,14±18,21: the fractions of top (T, species with no predators), intermediate (I, species with both predators and prey) and basal (B, species with no prey) species."[11]

It may not belong in the lead, but once again - let's worry about the body of the text and return to the lead after this has had time to take shape.Thompsma (talk) 16:18, 15 June 2011 (UTC)

• There's scope for a "Popular culture" section, believe it or not. The 2nd half of the song "Ilkley Moor Bar T'at" is a vivid example of a food web. --Philcha (talk) 10:06, 15 June 2011 (UTC) [12] --Epipelagic (talk) 13:29, 15 June 2011 (UTC)

Thanks for the input. I understand and appreciate your concerns on the level of ambiguity in some terms and how the lead just jumps into things. Remember that this article was in complete shambles last week and I still haven't had time to go through the base of the article. I've just been working on getting the citations put in using the correct formatting style and laying out the basic concepts that were never here prior. It seems to me that there are far more pressing needs in the overall shape of the article. Of course sections are going to be technical at this point. It takes time to whittle things down from being overly technical. There is always a natural progression to start technical and then to gradually work the material down to something that is more general - every experienced author will say this. The lead is not the place to start - the body of the article needs to be settled first so that we can identify the salient parts that need to go into the lead. Places where more constructive feedback would be welcomed would be the identification of major topic headings and how the scaffold of the article should take hold. A section on population culture might be fine - but seems less important in my mind until the scientific side is settled a bit. Evolution has a section on social and cultural responses - something like this could be added. If you would like to start this kind of section, feel free to do so. I do appreciate the feedback!!Thompsma (talk) 16:18, 15 June 2011 (UTC)

I agree that the lead should come last - I write and review this way. I don't think I can usefully contribute to the body of the article, as I have no experience of theoretical ecology. But if later you want comments from a reader who has some knowledge of biology, give me a call. --Philcha (talk) 21:23, 15 June 2011 (UTC)

Thanks Philcha - I guess it is a bit early to get editorial feedback and overwhelming to distill the subject down to a manageable size while conveying the meaning correctly. I've simplified some sections and will keep working through this. The topic of food webs is a big one to handle.Thompsma (talk) 05:12, 16 June 2011 (UTC)

Taxonomy of a food web

• There may be a better heading for this section. We should look again later. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• I think "heuristic concept map" contributes nothing. "heuristic" means at best "trial-and-error", which is easier to understand but still contributes nothing here. "concept map" may be useful as a temporary term when exploring a new topic, but should be replacement by a more specific type of model as the meaning and rules of its nodes and connection firm up - and "food web" is fairly well defined. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• The writing should be simpler, especially in the lead, the first section and if possible the start of other sections. The 1st page of "Food web patterns and their consequences" (Pimm etc., 1991) is a good example. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• "Food cycle is the antiquated term that is synonymous with food web" looks condescending, as some readers may only have seen "Food cycle". And you should explain why "food web" is now preferred. I note that you've also re-written Food cycle / Food chain. That article says, "A food chain differs from a food web, because the complex polyphagous network of feeding relations are aggregated into trophic species and the chain only follows linear monophagous pathways", which will literally be Greek to most readers, but, if rewritten in plain English, could be a concise, clear explanation of the difference between a food web and a food chain. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• Your diagram "A simplified food web illustrating ..." is very good, but I can seen improvements. First, show it larger - Wikipedia:Images#Image_preferences is just a guideline, and here a larger size would make the lettering legible (for fun, see the lead image of Paleontology). I'd removed the circle titled "Nodes containing trophic species", as "trophic species" would need explanation and the rest of the diagram is pretty clear. I'd make the "tropic links" box/arrow bigger, as at present its lettering is smaller that of the rest. And I'd use {{Annotated image}} to make the lettering normal text rather than part of the image, so that: the text can wiki-link, e.g. Decomposers; and users of non-English Wikipedias can change the language of the lettering without changing the image. Examples of {{Annotated image}} include: {{Annotated image/Extinction}}; {{Annotated image/Arthropod head problem}}, which uses lettering overlaying the image (e.g. "A", "x", "Mnd", etc.) and a colour-coded legend; and {{Annotated image/doc/Samples#Setting_defaults_for_annotations}} for a bit of fun. If we agree on using {{Annotated image}}, I'll do the coding and then copy the coding into the File Description page, as I did recently at the main parts of a generalised jumping spider. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• Your "biomass energy" links to biofuel, which is irrelevant. And outside of nuclear and high-energy physics, matter and energy are separate phenomena. You might find useful "Oxygenic photosynthesis accounts for virtually all of the production of organic matter from non-organic ingredients. Production is split about evenly between land and marine plants, and phytoplankton are the dominant marine producers" at Evolutionary_history_of_life#The_present, which gives a citation. --Philcha (talk) 19:03, 7 July 2011 (UTC)
• Rather than comment phrase-by-phrase, I'll try to rewrite the 1st para more clearly - tell me what you think. We can worry about additiion citations later, they should be easy. I include lots of examples so that, when the article moves into the most technical and abstract parts, general readers can say, "OK, A is an example of X and B is an example of Y". --Philcha (talk) 19:03, 7 July 2011 (UTC)

A food web depicts feeding connections (who eats whom) in an ecological community. Ecologists can broadly lump all life forms into one of two categories (trophic layers), the autotrophs and the heterotrophs. To maintain their bodies and to reproduce, autotrophs produce organic matter from inorganic substances, including both minerals and gases such as carbon dioxide. These chemical reactions require energy, which mainly comes from the sun and largely by photosynthesis, although a very small amount comes from hydrothermal vents and hot springs. Heterotrophs gain organic matter from autotrophs and from other heterotrophs by a variety of methods, which can be roughly divided into herbivory, carnivory, scavenging and parasitism. Some of the organic matter eaten by heterotrophs, such as sugars, provides energy. Both autotrophs and heterotrophs range from microscopic to many tonnes - from cyanobacteria to giant redwoods, and from viruses and bdellovibrio to blue whales.

The division into autotrophs, herbivores, carnivores, scavengers and parasites is not absolute, but shows the main "trade" or guild (ecology) by which each species lives. Many species may or must consume other types of nutrition as well as their main type, for example: carnivorous plants get at least a large part of their nutrition by eating animals, some animals are omnivores (including humans) and many predatory spiders also sip nectar; and many carnivores also scavenge animals that are dead but not too decayed, before bacteria and fungi take when is left. Most multicellular organisms also carry "hangers-on" whose role can range from parasitoids, which generally kill the victim eventually, to mutually beneficial symbiotes, a relationship which in both species benefit. For example malaria, caused by a few type of parasite, can be deadly if untreated, but bees fertilize flowers while sipping nectar and some ants eat plants but also guard them.

Thanks Philcha! A few comments. I agree that heuristic can be taken out of the lead - and it has been. However, I disagree with your statement "I think "heuristic concept map" contributes nothing", but I'm fine with it being removed. The idea of food web as a concept map is used in educational journals (see bioliteracy.org for examples). Moreover, ecologists often refer to the heuristic value of food webs, for example:

• "Food webs have high heuristic value for ecological theory..."[13]
• "Traditional trophic levels (e.g., autotrophs, herbivores, carnivores) have heuristic value when they are not connected in simple chains, but they are defined subjectively and ambiguously, and they have little to no analytical value today."[14]

Comments on food chain should be left aside for now - that article is a stub and I am fully aware of the technical nature of the writing. Your statement: "Food cycle is the antiquated term that is synonymous with food web" looks condescending, as some readers may only have seen "Food cycle"...." - I highly doubt that any reader would have seen food cycle - that term hasn't been in use for over 50 years. I don't see how it is condescending. There is no published explanation why food web is preferred that I am aware other than after Elton called it food cycle and the majority of others called it a food web afterwards. Food web was more 'catchy' for obvious reasons - but no paper that I have read has really commented on why it was preferred. It actually took a lot of sleuthing for me to find the transition and few papers refer to the switch without mentioning why. I think it is just simpler to say that food cycle was the original term that was replaced with food web. Perhaps the wording could be revised? I don't see much wrong with the existing text - but remain open to change.

Your comment about the figure is helpful and I will resize. Your comment on biomass energy is fine in terms of the link - Biomass (ecology) would be better. To state, however, that "outside of nuclear and high-energy physics, matter and energy are separate phenomena" - well that is false (e.g., [15], [16], [17], [18]) - ecologists have long considered the laws of thermodynamics in terms of energy:

• "As Lindeman (1942) pointed out, the amount of energy reaching each trophic level is determined by the net primary production and the efficiencies with which food energy is converted to biomass energy within each trophic step."[19]

The first paragraph of your proposed lead is great - the second paragraph needs some work. I have to run, but I will return to this and see what kind of adjustments can be made. Thanks again for your feedback - it is very helpful!!!Thompsma (talk) 22:17, 7 July 2011 (UTC)

I re-read your section on how to fix the image - looks great and looking forward to learn how to put the wiki linked text over the image. Here is a quote of information on biomass energy from Eugene Odum and Gray Barretts Fundamentals of Ecology[20]: "The standing crop biomass (expressed as the total dry weight or total caloric content of organisms present at any one time) that can be supported by a steady flow of energy in a food chain depends not just on its position in the food web, but also on the size of the individual organisms." Contrast this to: "And outside of nuclear and high-energy physics, matter and energy are separate phenomena." - Biomass is dry weight (matter) or total caloric content (energy) - hence both matter and energy are in biomass. The laws of thermodynamics and entropy with respect to matter and energy has been extensively discussed in the ecological literature using the same science that physicist use, except that ecosystems decrease internal entropy through the order of nature and increase external entropy in accordance to the laws of thermodynamics.Thompsma (talk) 05:25, 8 July 2011 (UTC)

Re matter and energy, I think we're look at the thing ideas from different perspectives. I'm looking at a web from the bottom up, and an autotroph "eats" inorganic matter and absorbs energy (mainly from the sun), and then uses some of the energy to build organic matter. Some types of organic matter can be used as chemical energy stores (e.g. sugars) by autotrophs, and by heterotrophs that eat autotrophs. --Philcha (talk) 11:00, 8 July 2011 (UTC)

It struck me that there's also a place for "top herbivores" - AFAIK no predator takes on a healthy adult elephant or rhino. --Philcha (talk) 10:49, 8 July 2011 (UTC)

All interesting ideas Philcha, but this is not the place for original research. You are correct about autotrophs absorbing inorganic and organic matter from the dirt and energy from the sun (but there is also energy in the absorbed matter). However, ecologists have a very precise definition of an autotroph with respect to production: production > energy expired during respiration. Of course plants have both mitochondria and chloroplasts - this is well known. The perspective I am coming from is sticking to the peer reviewed literature. This paper[21] talks about top herbivores.Thompsma (talk) 15:57, 8 July 2011 (UTC)

@Philcha...I hope my comment about original research didn't offend. It is a tough line in doing this work - trophic levels are a very complicated matter because some of the literature suggests abandoning the idea all together, while others suggest that it has informative content. I have had a lot of ideas spinning through my head as I have tried to synthesize this as well, such as your perspective on autotrophs feeding on dirt. I took a look at making the changes that you suggested for: "A simplified food web illustrating ..." - if you are willing to do the image map for this how should I send it? I can delete the text and leave it with you to put that information in. Please let me know. Thanks.Thompsma (talk) 18:30, 11 July 2011 (UTC)

I'm not offended, I know I've been using my GA-reviewer hat, and a thorough reviewer would ask about "top herbivores", etc. - reviewers can WP:OR to raise questions, the rest is up to editors. --Philcha (talk) 19:43, 11 July 2011 (UTC)

I liked your "some of the literature suggests abandoning the idea all together", which I can easily understand. But per "while others suggest that it has informative content" I can see that the idea is sensible, but may take a few centuries - I note your pic of a food web in a (?)bromeliad. --Philcha (talk) 19:43, 11 July 2011 (UTC)

I may be able to get the top web pic from the File page, otherwise I'll email you and you can reply with a copy of the pic. --Philcha (talk) 19:43, 11 July 2011 (UTC)

I got the top web pic from the File page, so there's no need for email. --Philcha (talk) 21:28, 11 July 2011 (UTC)

How to say how energy "leaks" from organisms, which it must, otherwise the Earth would be hotter than hell after over 3,000 billion years of life? --Philcha (talk) 21:28, 11 July 2011 (UTC)

"How to say how energy "leaks" from organisms..." - In Odum's terms of transformity you could say depreciation [22] - see chapter four. You will also be interested in the concept of phototrophic mixotrophy [23] [24] which might help with your confusion regarding autotrophic consumption. One of those papers defines "Autotroph: an organism that is able to use atmospheric CO2 as its sole carbon source, for example by way of photosynthesis."[25], even though it is peer-reviewed and in reputable journal - I'm a bit sceptical of the 'sole carbon source' as in mixotrophs (e.g., [26]). I'll have to research and think about this a bit further.Thompsma (talk) 22:46, 11 July 2011 (UTC)

The key to the paper I cited above re: mixotrophs is found in the definition of mixotroph: "'Mixotroph:' an autotrophic organism that combines its photosynthesis and a partial heterotrophy as carbon sources (synonyms: hemi-autotroph or partial mycoheterotroph). Indeed, a continuum from autotrophic to fully heterotrophic organisms exists in nature."[27]. This helps.Thompsma (talk) 23:14, 11 July 2011 (UTC)

Back to the top pic. How to show there that energy "leaks"? An obvious example is a dog panting, but where does the dog's used energy go ultimately? I'd guess as infrared radiated into space? If you can explain how and where and to where the "leaking" energy goes, then I think I can do version 2 of the pic, wrapped in an {{Annotated image}}. --Philcha (talk) 07:14, 12 July 2011 (UTC)

Hi Pilcha...I didn't understand that you wanted to include this into the illustration. I don't think it is really necessary to get the basic point across. That illustration is a remake of a simpler illustration that was in Kormondy's textbook and the leakage wasn't illustrated in that image either. You can see an energy flow diagram in the free online nature scitables article on secondary production [28] - they used a snail - I redrafted this image using a frog in the energy flow section. This is a replica of a stylized energy flow image that Eugene P. Odum used in his publications (e.g., [29]). Odum placed an E just below the outflow that he considered to be part of a production - even though it is waste, it is productive waste: "E refers to assimilated organic matter which is excreted or secreted (e.g., simple sugars, amino acides, urea, mucus, etc.). This "leakage" of organic matter, often in dissolved or gasseous form, may be appreciable but is often ignored because it is hard to measure." If you look at page 227 in the following article [30] - you can see how Howard T. Odum (Eugene's brother) - illustrated heat sinks, which is the energy dispersed into heat at each transformation. You could illustrate a heat sink stemming off each trophic species (node) - but it might clutter the image. I'll leave it up to you.Thompsma (talk) 16:24, 12 July 2011 (UTC)

Changes to lead

We should try to put headings so that we can address each issue in an organized way. I made changes to the lead and will repost what you suggested earlier:

A food web depicts feeding connections (who eats whom) in an ecological community. Ecologists can broadly lump all life forms into one of two categories (trophic layers), the autotrophs and the heterotrophs. To maintain their bodies and to reproduce, autotrophs produce organic matter from inorganic substances, including both minerals and gases such as carbon dioxide. These chemical reactions require energy, which mainly comes from the sun and largely by photosynthesis, although a very small amount comes from hydrothermal vents and hot springs. Heterotrophs gain organic matter from autotrophs and from other heterotrophs by a variety of methods, which can be roughly divided into herbivory, carnivory, scavenging and parasitism. Some of the organic matter eaten by heterotrophs, such as sugars, provides energy. Both autotrophs and heterotrophs range from microscopic to many tonnes - from cyanobacteria to giant redwoods, and from viruses and bdellovibrio to blue whales.

Here is what I did:

A food web (or food cycle) depicts feeding connections (who eats whom) in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs. To maintain their bodies, grow, develop, and to reproduce, autotrophs produce organic matter from inorganic substances, including both minerals and gases such as carbon dioxide. These chemical reactions require energy, which mainly comes from the sun and largely by photosynthesis, although a very small amount comes from hydrothermal vents and hot springs. A gradient exists between trophic levels running from complete autotrophs that obtain their sole source of carbon from the atmosphere, to mixotrophs (such as carnivorous plants) that are autotrophic organisms that partially obtain organic matter from sources other than the atmosphere, and complete heterotrophs that must feed to obtain organic matter. The linkages in a food web illustrate the feeding pathways, such as where heterotrophs obtain organic matter by feeding on autotrophs and other heterotrophs. The food web is a simplified illustration of the various methods of feeding that links an ecosystem into a unified system of exchange. There are different kinds of feeding relations that can be roughly divided into herbivory, carnivory, scavenging and parasitism. Some of the organic matter eaten by heterotrophs, such as sugars, provides energy. Autotrophs and heterotrophs come in all sizes, from microscopic to many tonnes - from cyanobacteria to giant redwoods, and from viruses and bdellovibrio to blue whales.

Any comments or feedback? I would like to put a link to growth and development - but those pages haven't been created. There are pages on human growth and human development - which is characteristic of our narcissistic species. Biological growth and development are very important research areas and deserve their own pages. I wonder if there is another link - such as Productivity (ecology) - which kinda gets the point across, but it is not the same as growth that is referred to in developmental biology. At some point I may create those pages. Thompsma (talk) 18:30, 12 July 2011 (UTC)

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