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Tuesday, June 08, 2010

Do animals "farm"?

Farming may be defined as the maintenance of crops and/or animals for the supply of food. It is a classical human function that began with the Neolithic Revolution some twelve thousand years ago.

But can non-human animals farm? There is one well-known example in the Animal Kingdom in which it might indeed be claimed that an animal "maintains animals for the supply of food". And that is the maintenance of colonies of aphids by ants to harvest honeydew secretions.

A colony of aphids ("blackfly or greenfly") sucking the sap from a plant stem. These insects are of course hated by gardeners!
Look carefully and you can see some ants crawling over the colony

A closer view of these fascinating little insects that form the bottom
of the food chain as prey for for other insects and birds.
Aphids exude a sweet, sugary secretion called honeydew, much favoured by ants


Zooming in, you can clearly see the ants attending the colony
(two are arrowed, a third is in silhouette on the left)


The ants are not predators of aphids; indeed they maintain them by protecting them from predators such as ladybirds, so as to maintain a continuous supply of the energy rich honeydew; a product of evolution by natural selection.

This appears to be a clear example of one animal (the ant) maintaining another (the aphid) as a supply of food, analogous to the maintenance by humans of cows for milk.

Could you call this "farming"? What do you think?

I took these pictures recently on my travels

14 Comments:

Blogger Limey said...

They're more of a mutual relationship than farming - the aphids also gain some benefits from the ants (reduced predation risk). The ant-fungi relationships are far more similar to farming.

2:16 pm  
Blogger Maalie said...

Yes, good point Limey.

2:25 pm  
Blogger lorenzothellama said...

I'm surprised you talk about 'farming' as I would have thought that was too girlie!

All sorts of animals live from each other like the little birds that sit on the back of rhino... (can't spell it), etc.

Also chimps 'fish' for termites. Is that fish farming?

2:42 pm  
Blogger Maalie said...

Lorenzo, your tick birds example is more like parasitism (or symbiosis if you think the rhinos benefit) but you can't really say that the tick birds actually "maintain" the rhinos!

And I don't think that chimps "maintain" termites in the same way as ants maintain aphids.

But interesting points, thanks.

2:46 pm  
Blogger Charles Gramlich said...

I call it farming, and the leaf cutter ants who pack leaves in their nests for fungus to grow on. Absolutely fascinating stuff.

3:19 pm  
Blogger Merisi said...

Perfect marriage! :-)

What's next? Antbucks?
Make that a Venti with a dash of honeydew, please! ;-)

4:26 pm  
Blogger Ted M. Gossard said...

Interesting, Maalie. Ants came to mind right away, but alas, my early fascination with ants was not followed up with proper observation and study. I certainly have no trouble believing that in some sense animals do "farm." It is interesting how life involves a chain of relationships for mutual good between living organisms. All the way if I may say, to us humans. Though maybe more a network with many interconnections rather than a chain I would suppose.

11:29 pm  
Blogger simon said...

I agree with Limey

12:03 am  
Blogger donsands said...

"..analogous to the maintenance by humans of cows for milk."

And hogs for pork?

Interesting post. Excellent photos.

3:14 am  
Blogger lorenzothellama said...

what about bees and pollenation?

8:41 am  
Blogger simon said...

Um.. I read a book called Animal farm.....

8:54 am  
Blogger Maalie said...

Thanks for comments everyone!

Donsands, I think the cows analogy is more realistic as neither the cows (for their milk) not the aphids (for the honeydew) are actually killed in the process, whereas pigs are slaughtered for their bacon.

Lorenzoo, I would say that bees/pollen is more symbiosis than farming because both organisms benefit. The key word is "maintenance" and bees don't maintain flowers in the same way that ants "maintain" aphids.

Merisi: Yes, quite a notion there! A honeydew cocktail would be quite sweet, I think!

Charles, that is a good example, similar to that suggested by Limey in which the fungi are maintained by provision of the leaves.

Ted, you are right, the term "food web" is far closer to reality than a simple "food chain".

Simon, thanks for your comment mate.

10:19 am  
Anonymous alcessa said...

Cleaner fish is an interesting case, too, but it really is a question who's farming who, if at all :-)

1:55 pm  
Blogger Lana Gramlich said...

That's a good question--one I'm not prepared to answer. I've often found such symbiotic relationships in nature very interesting, however!

3:59 am  

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