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...

A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates

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A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates

Abstract

Chelicerata is a megadiverse (over 120,000 species) arthropod clade that includes familiar taxa of profound ecological and economic importance, such as scorpions, spiders and mites1. Extant chelicerates share a unique anatomical character, the chelicerae—feeding first appendages terminated by a simple pincer-like chela2. The fossil record of these primarily predatory animals spans almost 500 million years3, suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods4,5,6, megacheirans4,7,8,9, habeliids10,11,12,13 and mollisoniids14,15 have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan’s origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.

Lerosey-Aubril, R., & Ortega-Hernández, J. (2026). A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates. Nature, 1-7. https://doi.org/10.1038/s41586-026-10284-2