Why does this ant react like this?

[ORF]

Hello

This is the video:


Question: why does the ant seem to be trapped by the ink circle?

Thank you for your time.

Regards,
ORF

 

[kuruman]

It's probably repelled by some chemical in the ink.

 

[quantknight]

Hello

This is the video:


Question: why does the ant seem to be trapped by the ink circle?

Thank you for your time.

Regards,
ORF

Ants follow up the line by sensing the scent left by other ants, it makes them to follow a direct single ordered path towards food or shelter so that they don't stray out of line. Forager ants search for food or shelter, by sensing through the scents across the plane. So when the plane is spreads with the scent of an ink, it senses that there is not a (right)path ahead of them. You can try this by wiping the line they go through. If you drew a circle across the ant, and leave an arc to escape, the ant will escape through it.
p.s this is just from a science lover's view, researchers can give you technicalities.

 

[jim mcnamara]

I did some research, and it very probably is related to pheromone trails -> chemicals left behind like bread crumbs in the Hansel and Gretel fairy tale. The ink in the pen disrupts the trail. In some unspecified way. However I cannot find an entomological paper on the specific subject at all.

Which raises questions about ant foraging. In a given colony the older ant individuals are foragers, meaning they are likely to die from all kinds of external hazards. It is sort of a calculated risk that normally provides more energy to the colony than is lost through forager mortality. This means any kind of large physical disruption e.g.:

hard rain,
a sandstorm,
a herd of grazing animals clomping through

will destroy the pheromone trails, effectively dooming any foragers out of the hive. So, hmm. Without some kinds mechanisms to prevent foraging in some oncoming bad circumstances sounds like a win, in terms bioenergetics. Can't find anything in the literature on that topic, either, after a short search. Any help out there?

 

[OmCheeto]

It's probably repelled by some chemical in the ink.

That was my thought. "Recommendations" after watching the video brought me to another video, with what looks like a "Clover mite" behaving the same way:



Googling for: volatile liquid in pen ink
took me to a paper that lists a few:

Determination of volatile organic compounds in pen inks by a dynamic headspace needle trap device combined with gas chromatography–mass spectrometry

Some harmful volatile organic compounds (VOCs), such as methylbenzene, ethylbenzene, xylene[*], chlorobenzene and bromobenzene, are the commonly found chemicals in pen inks.​

My guess is, that "benzenes" smell bad, to bugs, in general.

[*] per wiki: Xylene (from Greek ξύλο, xylo, "wood"), xylol or dimethylbenzene

 

[BillTre]

It is unfortunate that details on the pen/ink used were not given in the "methods" of the video.
If the experiment could be repeated, it would be interesting to see if it only worked with fresh ink as opposed to more "aged" ink where the volitol chemicals would have dissipated.

 

[mrix]

Another interesting experiment here where the ant does not see the pen circle as a false barrier Ant Trapped in Circle.