In a fascinating discovery published in the journal Ecology and Evolution, entomologist Mark Moffett from the Smithsonian's National Museum of Natural History has observed an intriguing interaction between two ant species in Arizona's Chiricahua Mountains. This dynamic mirrors the relationship between cleaner fish and larger fish in aquatic ecosystems, where the former remove parasites and dead skin.
Moffett describes the newly identified ant species as the terrestrial equivalent of these cleaner fish. Remarkably, the larger harvester ants (Pogonomyrmex barbatus) allow smaller cone ants to groom them, even permitting access between their open jaws.
A Chance Encounter Sparks Insight
While enjoying coffee at a research station, Moffett noticed some harvester ants behaving unusually. Unlike their typically active nature, these ants were still, prompting him to investigate further. Upon closer examination, he discovered they were covered in tiny cone ants.
Initially suspecting aggression, Moffett quickly realized that the larger ants were inviting the smaller ones to groom them, indicating a mutualistic relationship rather than hostility.
The Grooming Process Unveiled
Over several days, Moffett documented interactions involving at least 90 harvester ants and the smaller cone ants from an undescribed species in the genus Dorymyrmex. The grooming sessions followed a predictable pattern: a harvester ant would approach a cone ant nest, stand with open mandibles, and wait for a cone ant to emerge. Up to five cone ants would then engage in grooming, using their tongue-like mouthparts to clean the harvester ants' bodies.
These sessions varied in duration, lasting anywhere from 15 seconds to over five minutes. The larger ants remained passive during the grooming process, shaking off the smaller ants once finished.
A Unique Interaction in Nature
Moffett notes that this behavior is unprecedented in his experience with ants or other insects. The closest analogy exists in marine environments, where fish visit "cleaning stations" to have parasites removed by smaller species. Interestingly, the cone ants displayed a preference for live ants, ignoring deceased ones nearby.
Mutual Benefits of Grooming
Researchers are still exploring the advantages of this interaction for both species. Moffett speculates that the cone ants may benefit by consuming nutrient-rich particles from the harvester ants' bodies, potentially remnants from the seeds they collect. Additionally, the harvester ants may gain from the thorough cleaning provided by the cone ants, which could reach areas that are typically hard to access.
A Glimpse into Nature's Wonders
This discovery serves as a reminder of the vast unknowns within animal behavior, particularly in natural habitats. Moffett emphasizes the importance of observing the intricacies of nature, stating, "Many remarkable discoveries await us outside the lab, and paying attention to the small things, like ants, can lead to significant insights."
