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 (42 ms) was similar to that seen in other slow-moving ants. We determined the flicker fusion frequency of the compound eye at the brightest light intensity to be 132 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 0.5 cycles deg−1 and reached peak contrast sensitivity of 2.9 (35% 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.

Unraveling the neural basis of spatial orientation in arthropods

“…The physical properties of the dioptric apparatus and the physiological properties of the photoreceptors define the limits of the visual information that can be perceived. Yuri Ogawa and colleagues investigated the anatomical and physiological properties of the compound eyes of the green weaver ant (Ogawa et al 2023 ). The ants are diurnal and use vision for navigation and prey capture.…”

A simple mechanism for collective decision-making in the absence of payoff information

“…This is unlikely, however, as we observed chain initiation in all our experimental conditions and even when the distance from the target was set at 110 mm. O. smaragdina major workers are visual predators and navigators with highly developed eyes that are well-tuned for diurnal light conditions ( 43 , 44 , 51 – 53 ). Although no comprehensive study on the visual capabilities of O. smaragdina workers exists, comparisons of O. smaragdina eye anatomy with that of other ants ( 52 – 54 ) suggest that weaver ants should easily detect the platform stimulus in all of our experimental conditions.…”

“…O. smaragdina major workers are visual predators and navigators with highly developed eyes that are well-tuned for diurnal light conditions ( 43 , 44 , 51 – 53 ). Although no comprehensive study on the visual capabilities of O. smaragdina workers exists, comparisons of O. smaragdina eye anatomy with that of other ants ( 52 – 54 ) suggest that weaver ants should easily detect the platform stimulus in all of our experimental conditions. Our results also show that ants were more likely to lengthen a chain with their bodies when closer to the platform and that the probability of observing “reaching” behavior also increased with the proximity to the target.…”