It is the lot of some ants to prune shrubs and that of other ants to cut the grass. Of course, both species teach a similar proverb to their youngsters, namely ‘many mandibles make light work’. To make this come true, they have to have excellent communications in spite of having no access to Twitter. It is a no-brainer to come up with the idea of a worker marching off to work, making inquiries as to where to go from those bringing back heavy loads of loot. But things are rather more interesting than that.

Bollazzi and Roces (1), of U of Würzburg, have investigated the cutting rules that the workers use and shown that they can choose to cut longer or shorter lengths of grass blade depending on how much help is needed to bring in the harvest. Intuition would suggest that if there’s pressure to bring in the harvest, they would cut longer lengths, and thus make fewer journeys. But here, our intuition lets us down. They cut shorter lengths because they can run back with these and not slowly stagger back with a great long blade. Getting there and back more quickly, and hence more often, mean more chats with those on break and more recruits to the field and, ultimately faster completion of the harvest.

The grass cutting ants don’t eat the grass but use it as fodder for their fungus. Herbivores like cows and tortoises consume the grass they cut directly and have developed strategic digestive help that requires energy input to get the metabolism to work. Bigger is usually considered to be better in the engineering world of methane digesters, but our cows main purpose is not to produce methane but to produce milk. The eating problem then, is to use as much of the energy input as possible to go to nutrition and instead of gas production. Again bigger produces economies of scale and large mammalian herbivores were assumed to be proof of this principle (the Jarman-Bell principle).

Recent work is at loggerheads with the concept of bigger as being more efficient and that to the contrary, larger production units result in more waste in the form of useless production of methane. Tortoises come in different sizes but none as big as cows, so the question arises ‘Does this principle apply to them?’ Well tortoises work out just like cows. Size does not mean greater efficiency as Clauss’s team based at U of Zurich have shown (2).



One Response so far.

  1. jazgal says:

    Really, if I could get the ants on my property to put their attentions to grass cutting, they would be most welcome. Instead, they seem most inclined to take over the ancient wooden window frames, and especially, my mailbox post, as the perfect spot to set up shop. I have yet to find any fungal gardens, but still. that would be more welcome than not.
    I don't know how I feel about tortoises chewing up the foliage, as they haven't been around either, but I do wonder about the methane/milk production ratio for cows, since we know that they do produce tons of methane.

Leave a Reply