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Besides fruits and milk, what other examples are there in nature where it is beneficial for a species to have some part of its biomass eaten by others so that it evolved to produce nutritious parts to be eaten by other organisms? For example, plants having animals eat their fruits as a means of transporting their seeds.

Update.

I think there are at least two philosophically different scenarios that interest me.

One is when the substance is intended to be eaten by the same species (example: milk).

The other is when it is intended to be eaten by another species (example: fruits).

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closed as primarily opinion-based by kmm, MattDMo, rg255, James, AliceD Sep 5 '16 at 10:03

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ I agree with @Arnb below, this is not a bad question. Will edit to clarify. $\endgroup$ – Roland Sep 3 '16 at 21:22
  • $\begingroup$ Thanks to @Roland's edit the question now makes sense. It is an interesting question. I am removing my close vote, my now obsolete comment and +1 $\endgroup$ – Remi.b Sep 3 '16 at 23:44
  • $\begingroup$ Difficult to define "intended" seeing as there is no intent in evolution - lactation provides for offspring, fruit is taking advantage of heterospecifics to spread seed, nectar is an incentive which makes animals aid pollination, all photosynthetic plants convert sunlight to edible energy but is it "intended" for using within the plant or could it be an evolutionary precursor to "intent" to feed conspecifics and heterospecifics? $\endgroup$ – rg255 Sep 4 '16 at 20:35
  • $\begingroup$ Let's say intent means both the food stuff and the interaction evolved by selection with benefits in both species. Did evolution intend for fruit production? Maybe the fruit around the seed was a good way to provide a nutrient rich early environment, or helps the seed float in water to spread it, and then animals came along and started eating them $\endgroup$ – rg255 Sep 4 '16 at 20:46
  • $\begingroup$ This is similar to an egg, the egg provides a nutrient rich environment for the chick to grow, humans (and other species) came along and started eating them. $\endgroup$ – rg255 Sep 4 '16 at 20:49
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There are plenty of examples! Here is a short list

  • Defence ("Eat that so that you don't eat this")
    • Evisceration. It is the ejection of internal organs so that predator eat them but not the prey entirely. (sea cucumber does evisceration)
    • Lizard's tail being fragile on purpose
  • Parental care
    • Milk
    • Regurgitation
    • Sexual Cannibalism (as it is often hypothesized as benefiting the male also as he indirectly nourish his offspring)
    • In haplo-diplontic species, one of the two generation can be much bigger and can transfer its nutrient to the other generation (offspring), such as in moss for example.
  • Mutualism
  • Symbiosis
    • Lichen
    • Root nodule
  • Social behaviour
    • Honeypot ant (if we are happy to consider the honey stored in the ant for a long being part of the ant biomass).
  • Human related
    • The researcher in parasitology that feed his mosquitoes with his own blood!
    • Crops (and other things) under artificial selection. It is here just cases of mutualism where humans is involved.
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  • $\begingroup$ Another point which you may incorporate: Plants also produce another kind of nectar (extrafloral nectar) to attract ants and other insects which protect them (plants) from herbivores. $\endgroup$ – WYSIWYG Sep 4 '16 at 5:01
  • $\begingroup$ I don't think evisceration of sea cucumbers is actually intended to feed and satisfy the predators (as per wikipedia). It is for trapping and immobilizing them. $\endgroup$ – WYSIWYG Sep 4 '16 at 5:04
  • $\begingroup$ I did not use the word "biomass" in the original question. $\endgroup$ – Anixx Sep 4 '16 at 6:43
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    $\begingroup$ Please don't editorialize in your answers. If you want to respond to a particular member or comment, use a comment. Otherwise, use Biology Meta. That's what it's there for. I realize we were just discussing this, but at this point there are two answers (one is mine) against your point of view with a total of 7 upvotes, and one answer (your own) which has been downvoted (disagreed with) once. If you want to speak critically about the post, please use comments like everyone else. I won't downvote your post this time, but it's an option in the future. $\endgroup$ – MattDMo Sep 4 '16 at 14:03
  • $\begingroup$ @MattDMo I removed the section 'Semantic issue in the post'. I really find this refusal of any discussion of semantic in answer silly but it looks like the majority of user like it this way, so I will just comply to the majority. Thanks for the comment then! Without this section, it will be likely to have discussion in comments of the kind as those we have underneath Arnb answer though. Btw, I upvoted your comment by mistake :) $\endgroup$ – Remi.b Sep 4 '16 at 17:28
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I found this question very interesting. Let me explain. In the course of evolution, all organism developed properties (may be structural, functional or other) to protect themselves from predators. It may be by mimicry or development of some defensive or offensive methods. There are only a few exceptions to that - where the organism allows other organisms to eat its body parts. In the question the "intended to be eaten" indicates this. With this sacrifice surely the organism gets some survival advantages of itself or its children. Fruit and milk are among these rare examples.

Another example should be nectar of flowers. Plants make nectar so that bees visit flowers to drink it and unknowingly spread the pollen.

There should be other examples also.

Please note the tag "evolution".

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  • $\begingroup$ So, one seemingly should add honey, anything else? $\endgroup$ – Anixx Sep 3 '16 at 18:29
  • $\begingroup$ What about mushrooms? $\endgroup$ – Anixx Sep 3 '16 at 18:38
  • $\begingroup$ @Anixx nectar, not honey. Honey is produced by bees as food storage for their colony, and they certainly are not intent on giving it away to other species. Hence all the angry buzzing when beekeepers harvest their hives. $\endgroup$ – Roland Sep 3 '16 at 21:18
  • $\begingroup$ Please don't editorialize in your answers. If you want to respond to a particular member or comment, use a comment. Otherwise, use Biology Meta. That's what it's there for. $\endgroup$ – MattDMo Sep 3 '16 at 21:59
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    $\begingroup$ I used first person in my answer for the sake of simplicity. Otherwise I had to say "in the process of evolution the plants with their seeds covered with edible fruits got naturally selected with respect to other non-fruit-bearing plants of same hierarchical category. The primary purpose of the fruit is its edibility. In other words fruits are evolutionarily selected to get eaten. " To avoid this long and complex sentence I used terms such as " allows" in my answer. I didn't use "decide" in my answer. So MattDMo please keep it out of quotation marks. $\endgroup$ – Arnb Sep 4 '16 at 5:29
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In many species (crickets, salamanders, newts, arachnids, moths) males provide a nuptial gift in the form of a spermatophore which aids the female if consumed (normally via additional nutrition, but in some species the package may contain toxins that make the female less susceptible to predation).

Also, @Arnd mentions nectar in the context of encouraging fertilisation but extrafloral nectaries are believed to have evolved specifically to produce nectar for consumption, in this case by insects that will attack herbivores and thereby indirectly protect the plant.

You could make a case that bitter or toxic secretions that are intended to discourage predation have evolved specifically to be consumed, but I suspect that's not really the way this question was intended.

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  • $\begingroup$ "You could make a case that bitter or toxic secretions that are intended to discourage predation have evolved specifically to be consumed, but I suspect that's not really the way this question was intended." - yes! $\endgroup$ – Anixx Sep 4 '16 at 22:59
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I think cannibalism in caterpillars is an example. Especially the larvae of the Lyceanidae, but also anthocharis cardamines are canniballistic. The caterpillars often find themselves on a plant that is too small to sustain more than one of them. Cannibalism is then beneficial to the species, because one butterfly is better then ten starved larvae. As cannibalism also makes the caterpillars grow faster, it could (hypothesis, not proven afaik) be a survival strategy (or semantically more correct: trait).

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