Hunting ecology predicts eye arrangements in the modular visual system of spiders

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  Hunting ecology predicts eye arrangements in the modular visual system of spiders Summary Vision is one of the most important senses used by animals and contributes to fundamental behaviors, including foraging, navigation, and mate detection and selection. 1 Although much is known about how eye position and orientation correlate to ecology in the context of binocularity, 2 animals with multipartite visual systems (more than two eyes) remain comparatively neglected. Spiders are highly successful predators that occupy a range of ecological niches and usually possess eight eyes. Here, we use three-dimensional geometric morphometrics and evolutionary modeling to test whether eye positions, orientations, and interocular angles correlate with hunting strategies in 52 species across the spider phylogeny. We demonstrate that eye configurations diversified from an ancestral medial cluster, as seen in modern trapdoor spiders, to a halo-like configuration in orb-weavers, and to the fronta...

Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics

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Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics

ABSTRACT

Arthropods are traditionally viewed as invertebrate prey and as predators of other invertebrates, whereas vertebrates are typically considered their predators. However, this paradigm has increasingly been challenged, particularly among arachnids. While several invertebrates are well documented as frog predators, the capacity of particular groups, such as harvestmen (Opiliones), to prey on vertebrates has remained largely anecdotal. Here we report novel field observations of anuran predation by multiple Cranaidae harvestman species across several Neotropical localities. These records include the active capture and consumption of live frogs, demonstrating their role as opportunistic mesopredators. Our findings expand current knowledge of Opiliones ecology by confirming that vertebrate predation occurs across multiple species and localities. Our results suggest that vertebrate consumption among arachnids may be more taxonomically widespread than previously recognized, highlighting the need to consider Opiliones as potential predators in Neotropical trophic networks.

Calvache, E., Villarreal, O., Ávila-Rojas, C., Bentley, A. G., Brito, K., Correa-Zanotti, C., Gutiérrez-Arboleda, M., Iñiguez, K., Narváez, J. C., Proaño, L., Reyes-Vizcaíno, M., & García, L. F. (2026). Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics. Ecology and Evolution, 16(4), e73542. https://doi.org/10.1002/ece3.73542