Ant Rafting in an Extreme Ecosystem

Abstract

Ants are among the most abundant organisms on Earth, being adapted for living on different solid surfaces. However, in some habitats, like riparian forests and flooded plains, water can be a constant obstacle, and overcoming this obstacle can be essential to determine the persistence of ants in such habitats. While most ant species avoid the water during a flood by foraging at higher elevations or climbing on trees, a few species developed ways to overcome this obstacle by swimming. Here, we report, for the first time, ants of the species Linepthema micans (Forel 1908) performing rafts. We observed 14 rafts in three consecutive days at approximately 1400 meters a.s.l. in Serra do Cipó, Brazil. Notably, this is the first record of ant rafting in tropical mountaintop grasslands, which are extreme habitats with shallow and sandy soils, and where small temporary water pools are extremely common in the wet season.