The research team, led by Thomas E. White and Noah Brown, focused on three taxa that co-occur across coastal and montane New South Wales: Hadronyche cerberea, Hadronyche versuta and members of the Atrax robustus complex. The latter grouping is treated at the complex level because Atrax robustus was recently split into three species, A. montanus, A. robustus and A. christenseni, and webs cannot yet be reliably assigned beyond the complex in the field. Together, the three focal taxa span the major architectural categories previously described for the family, including entrance-associated, lattice and open-hole web forms, making them a tractable comparative system that captures much of the recorded structural diversity in Atracidae.

Methodologically, the study is notable for what it did not do. Consistent with the medical risk posed by atracids, the researchers never collected, handled or excavated a single spider. Instead, they systematically searched eight sites across three regions of New South Wales, the Central Coast, Greater Sydney and the Southern Highlands, photographing burrows in embankments, logs, crevices and tree cavities with a smartphone camera held as close to perpendicular to the web surface as possible, with a scale reference in every frame. Species identity was assessed from web and burrow architecture combined with the external morphology of spiders visible at burrow entrances, evaluated against regional taxonomic keys. Image screening removed photographs with substantial obscurity, poor focus or incomplete structures, leaving final samples of 13 webs for the Atrax robustus complex, 13 for H. cerberea and 9 for H. versuta.

The analytical workflow converted those photographs into numbers. Each calibrated image was imported into Fiji, an open-source image analysis platform, and the researchers delineated two functionally distinct regions of interest. The sensory zone was defined as the full extent of the web, including all radiating triplines, representing the area over which the spider could plausibly detect substrate-borne vibrations from prey. The capture zone was defined as the subset of silk near the burrow entrance showing visibly denser threads, corresponding to the region most likely involved in physically intercepting prey. This division maps directly onto the two phases of atracid hunting: these are sit-and-wait ambush predators that remain inside their burrows until prey contact a tripline or entrance silk, at which point they rush out, seize the prey with their chelicerae and drag it back underground.

From convex hull polygons traced around each zone, the team extracted four morphometric metrics: area, circularity, aspect ratio and the sensory-to-capture allocation ratio. Principal component analysis showed that the first two components explained 68.6 percent of total variation, with the sensory-to-capture ratio dominating the first axis and overall web area and shape dominating the second. Permutational multivariate analysis of variance confirmed statistically significant differences both between web zones and among species, with all pairwise comparisons among the three taxa significant. The numbers affirm what field naturalists had long suggested qualitatively: these species build genuinely different webs, and the differences are consistent enough to measure.

The species-level patterns are striking. Hadronyche cerberea, found exclusively in arboreal contexts on the Central Coast, where it occupies fissures, heartwood pipes and borer holes in trees such as Casuarina, Melaleuca, Banksia and Eucalyptus, builds the largest webs of the three, with a mean sensory zone of 13,230 square millimetres and a mean capture zone of 1,436 square millimetres. Its webs typically feature two to three entrances connected by a thick silk tube, each surrounded by a dense lattice that radiates outward in a fan-like arrangement, with long triplines extending in a wide-angled distribution. Its mean sensory-to-capture ratio of 23.94 was by far the largest and most variable of the three taxa, indicating heavy proportional investment in detection rather than interception.

The Atrax robustus complex, by contrast, builds the smallest and most irregular webs, with a mean sensory zone of 5,940 square millimetres, a mean capture zone of 870 square millimetres and the lowest sensory-to-capture ratio at 7.18. Its stereotypical design is asymmetrical, commonly with two to six entrances interconnected by a dense-mesh silk atrium, and concave crescent flaps held slightly open even when not in use. Triplines extend outward erratically, branching and intersecting, and lattice density rarely decreases with distance from the entrance. Hadronyche versuta occupies an intermediate position, with a relatively symmetrical web built around an open-hole entrance, a dense lattice of thick silk radiating fully around the burrow, and the highest circularity values in both zones, indicating the most regular outlines. Its sensory-to-capture ratio of 8.98 sits close to that of Atrax.

These architectural differences appear to encode different trade-offs between prey detection, capture efficiency and predator avoidance, although the authors are careful to note that their functional interpretations remain inferential, since they did not observe prey capture, quantify prey availability or manipulate web structure. The arboreal H. cerberea, facing reduced prey abundance and elevated predation risk from visual predators such as birds, appears to favour extensive sensory coverage over a large capture area, with a smaller capture zone limiting the distance the spider must travel from its camouflaged, reinforced silk tube. The Atrax complex invests proportionally more in its capture zone through fine silk sheets but has a reduced sensory range, while H. versuta, which lacks an obvious defensive structure despite facing comparable terrestrial predators, may compensate through earlier threat detection via a broadly radial distribution of triplines providing near-uniform angular coverage around its entrance.

Intraspecific variation was also evident, and along different axes for different species. H. cerberea varied primarily in functional investment, with individuals differing in capture zone allocation while maintaining a consistent overall shape, largely reflecting differences in silk tube configuration and entrance number. The Atrax complex varied most in web shape, showing plasticity in overall form while consistently emphasising the capture zone. H. versuta showed the least variation overall. Ontogeny appears to contribute as well: in both Hadronyche species, smaller and likely juvenile individuals built simpler, smaller designs with less developed lattices, a pattern consistent with observations in tarantulas where web complexity increases with maturity. Microhabitat also shaped structure, with tripline number and length in H. versuta depending on adjacent substrates around the burrow entrance.

Beyond its evolutionary interest, the study has immediate applied value. Burrow and web architecture has already proven a reliable diagnostic feature for distinguishing trapdoor spider genera such as Euoplos and Cryptoforis, including sympatric populations, and the consistent differences quantified here provide a similar basis for field identification of H. versuta, H. cerberea and the Atrax robustus complex without excavating individuals, a process that poses serious safety risks with atracids. Potential applications span ecological surveys, medical identification, antivenom collection and future research. The authors propose that expanding this work to include additional species, particularly the genus Illawarra, and integrating behavioural assays of prey detection and capture with architectural data would allow the functional hypotheses to be tested directly. Data and code are openly archived via Zenodo, and the quantitative framework is readily applicable across the Mygalomorphae, offering a path toward understanding how silk use has shaped the ecological and evolutionary success of one of the oldest lineages of spiders.

Subject of Research: Ecology

Article Title: Inter‐ and Intraspecific Variation in Web Architecture and Its Significance in Australian Funnel‐Web Spiders (Atracidae)

Article References: Brown, N., & White, T. E. (2026). Inter‐ and Intraspecific Variation in Web Architecture and Its Significance in Australian Funnel‐Web Spiders (Atracidae). Ecology and Evolution, 16(10), Article e74473. https://doi.org/10.1002/ece3.74473

Image Credits: AI Generated

DOI: 10.1002/ece3.74473

Keywords: Inter, Intraspecific, Variation, Architecture, Significance, Australian, Funnel, Spiders, Atracidae, scientific research