WatchingAnts is always interesting.

Today I watched ants stream between a hole in the wall, presumably leading to their nest, and some distant food supply.

As usual as the ants passed each other, they would typically touch head-to-head (or antenae-to-antenae) then break and continue.

One ant was returning, carrying some flake of food, several times larger than her body. As the outgoing ants passed they touched either the food or her, then continued. I watched 10 or 12 do this, then one stopped, locked onto the food particle, and started to help drag it more rapidly towards the nest.

Why? Was this in fact some different kind of worker, whose role was to help another drag the food back? Or was she an ordinary worker in exceptional circumstances? Had the original carrier suddenly signalled she needed help to carry the food over a particularly hardgoing patch?

The two worked together, pulling the food towards the nest. Other ants passed, touched them, and touched the food and continued. No others stopped to help. Had circumstances changed again; the two now dropping "it's under control" signals? Or had the original "help me" signal simply stopped? Or were these ants totally autonomous, but specialized by type of food? So that the original helper joined in because this was her area of concern?

The two dragged the food on. At one point, the helper actually riding upside-down on top of the food, legs pushing against the wall. Like a bargeman in a low tunnel, pushing against the roof with his legs. Then, this helper fell off, the original ant kept moving, pushing the food towards the nest; and within seconds the helper was left behind, maybe 25 mm or more (these were small ants). The helper ran in circles for a second, and then chased the food. She rejoining her sister, and grabbed the food particle. For a brief period, although separated and disengaged from the task ,she clearly remembered that's what she was meant to be doing. (Or did she just chase a hot chemical lead towards food and rediscover it again?)

Later she fell away again, and this time lost the food entirely. She began following the outward trail again.

So did the original ant signal her help was no longer needed? Or was the falling off both times accidental, but in the fist case followed by recovery, while the second case, attempt at recovery failed. Or was the first case a deliberate abandonment, followed by an amnesic rediscovery of the food which she should have simply ignored?

Here in this part of Brazil there seem to be two sizes of ants :

  • much bigger than those in UK
  • much smaller

Presumably this is a stable polymorphism. The ecology supports the two sizes, but not UK sized

Ants on tree - large, but bark of tree is also large. Do tightly coupled ecological systems evolve to the same scale?

(See also Graham's question OnMarkets/SeekingSimilarStatus, OnScale)

Some experiments with how the nest responds to changes in forager return.

Another interesting thing about ants. The ants move and the messages (chemical trails) stay put. From a MediaAndMaterials perspective ants should be highly religious :-)

And contrast DomainsAndParticles