Physiological properties of the visual system in the Green Weaver Ant, Oecophylla smaragdina

Abstract

The Green Weaver ants, Oecophylla smaragdina are iconic animals known for their extreme cooperative behaviour where they bridge gaps by linking to each other to build living chains. They are visually oriented animals, build chains towards closer targets, use celestial compass cues for navigation and are visual predators. Here, we describe their visual sensory capacity. The major workers of O. smaragdina have more ommatidia (804) in each eye compared to minor workers (508), but the facet diameters are comparable between both castes. We measured the impulse responses of the compound eye and found their response duration (42ms) was similar to that seen in other slow-moving ants. We determined the temporal resolution of the compound eye at the brightest light intensity to be 131.54 Hz, which is relatively fast for a walking insect suggesting the visual system is well suited for a diurnal lifestyle. Using pattern-electroretinography we identified the compound eye has a spatial resolving power of 0.52 cycles deg− 1 and reached peak contrast sensitivity of 2.88 (34.67% Michelson contrast threshold) at 0.05 cycles deg− 1. We discuss the relationship of spatial resolution and contrast sensitivity, with number of ommatidia and size of the lens.

Leaderless consensus decision-making determines cooperative transport direction in weaver ants

“…), suggesting that ants may be able to access directional information using pheromone trails, removing the need for temporary leaders to guide the group. Weaver ants also possess large eyes and rely heavily on visual information for navigation (43, 66). They use celestial cues to derive compass information, but can also use artificial light and distal landmarks when necessary.…”