Turtle Ants (Cephalotes)

My main research is on the ant genus Cephalotes. This genus is strictly limited to the New World and most are found only in the Neotropics.

As far as we know, all Cephalotes are arboreal cavity nesters, and they are one of the few genera where most of the species have a morphologically distinct soldier caste. Unusually, however, Cephalotes soldiers do not have enlarged mandibles for combat, like soldiers in other groups. Instead, they have broad heads, with an elaborate disc-like structure in some species, which they use to block the entrances of their nests.

There are 131 known species of Cephalotes (115 extant, 16 extinct; de Andrade & Baroni Urbani 1999) and although nests are often small and hard to find, these ants can be locally very diverse. For instance, at my primary study site in Brazil, I have located the nests of 17 species. Not a bad species count for a single genus of arboreal ants! My total for all of my sites now includes four species new to science.

My research on this group is focused primarily on the patterns and processes of ecological and phenotypic diversification within the genus, with particular attention given to the evolution of the specialized soldier caste. I am also working on Cephalotes community ecology, which includes collaborative projects with Heraldo Vasconcelos and students at the Universidade Federal de Uberlândia. I will post more information of the specific questions I am addressing with Cephalotes soon, but for now check out some of my Cephalotes photos

Army Ants (Ecitoninae)

New World army ants (Formicidae: Ecitoninae) are all nomadic social predators, which means that colonies relocate regularly and that foraging is always conducted in group-raids, with a large number of workers simultaneously seeking-out and capturing prey cooperatively.

Colony movement occurs on a regular basis, and in many species, it follows a repeated cycle of about 35 days, with two distinct phases. In the 'nomadic phase', which lasts about 15 days, a colony relocates to a new nest site almost every night, and in the 'stationary phase', of about 20 days, a colony nests at a single site. This cyclical pattern is closely correlated with the production of synchronized brood cohorts. In the stationary phase, the queen lays tens of thousands of eggs over a period of about ten days, and the previous cohort undergoes metamorphosis. At the end of the stationary phase, the eggs hatch into larvae and the previous cohort ecloses, providing the colony with a large number of new adults. The colony then enters the nomadic phase and in this period the larvae undergo full development. As the larvae begin to pupate, the colony enters the stationary phase once more, and the cycle repeats. Remarkably, at each location a colony moves to, they do not build a conventional nest in the soil or preformed cavity like most ants. Instead, they build a nest, or 'bivouac', from living ants, with a proportion of the workers forming the structure of the nest and the others caring for the brood and queen within.

In most species, the group raids consist of narrow 'column-raids', which can extend over distances of more than 100 meters in search of specific ant prey. However, in two species (Eciton burchellii & Labidus praedator), group-raiding is taken to an extreme in the form of 'swarm-raids', which consist of a dense carpet of ants that can be over 10 meters wide. This raiding method allows these two species to capture a wider range of prey than the column raiders, and famously attracts many different species of birds that capture fleeing prey and prey not fully overwhelmed by the ants.