Ectatomma opaciventre is a South American species of ant from the subfamily Ectatomminae.

[2] Nests are excavated in soil and can be up be up to 68 cm deep, and comprise multiple sub-chambers.

Workers forage diurnally, scavenging and predating live arthropods (primarily leaf cutter ants and termites).

However, E. opaciventre has the least diverse diet of studied ants from the genus, and unlike others, does not collect liquid food.

Various mechanisms are used by different species, including tandem running, pheromone trail laying, and 'adult transport' where workers carry adult nest-mates.