In a laboratory colony, a Cephalotes rohweri turtle ant soldier demonstrates how she uses her massive head to block the nest entrance. She is essentially a living door, and will not admit any ants other then her own nestmate. The second ant here is a Crematogaster acrobat ant, perhaps the turtle ants' biggest competitors for living space. Tucson, Arizona, USA
Cephalotes varians turtle ants. To enter her nest in a mangrove twig, a foraging worker must pass the door-guarding soldier whose head is roughly the same size and shape as the entrance. These ants don't build the nests themselves; rather, they inhabit burrows made by beetle larvae. Florida Keys, USA
Cephalotes rohweri, the Arizona turtle ant. The broad head disc of this soldier is used in nature to block the nest entrance. This species nests in old burrows of wood-boring beetles and constantly faces usurpation by competing ants. Tucson, Arizona, USA