If you’re like me (and I know many of you are), you spend a fair amount of time poking about in ant nests. Nests usually contain developing larvae, of course, which some species maintain in an ungainly pile. In others, young are spaced along the walls and roof of the chambers. Like so:
How do ants hang their larvae? Thanks to a simple experiment published today by Clint Penick in PLOS ONE, now we know: larvae of a particular age have little anchors.
Not all larvae of all species have these hooked hairs. Rather, the structures appear in older instars of several disparate myrmicine genera like Pheidole, Cephalotes, Crematogaster, Strumigenys and Temnothorax, among others. I had a look through my old photos. Sure enough, for the indicated taxa, many larvae appeared hairy and/or stuck to something.
To confirm the function of the anchor hairs, Penick et al performed an obvious test of the velcro hypothesis: They gave the grubs a haircut.
If the larvae still adhered to the test walls, some other mechanism must be at work. If the larvae fell, the hypothesis is supported. How well did shorn larvae stick?
Poorly, if the walls were vertical, and hardly at all at greater angles. An elegant result! It appears the hairs-as-anchors hypothesis is correct.
And as far as I know, this may be the first time ant babies have been given haircuts for science.
source: Penick CA, Copple RN, Mendez RA, Smith AA (2012) The Role of Anchor-Tipped Larval Hairs in the Organization of Ant Colonies. PLoS ONE 7(7): e41595. doi:10.1371/journal.pone.0041595