A pseudoscorpion clinging to a cave salamander: phoresy or failed predation?

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  A pseudoscorpion clinging to a cave salamander: phoresy or failed predation? Abstract Pseudoscorpions are well known for phoretic associations with arthropods, but interactions with amphibians are rarely documented. Here we report a pseudoscorpion attached to the left palpebral region of an adult male Italian cave salamander, Speleomantes italicus , observed during a visual survey in a karst cave in Tuscany, Italy. The pseudoscorpion, assigned on the basis of visible morphology and locality to Chthonius cf. elongatus , was grasping a minute cutaneous fold on the lower margin of the left upper eyelid with one chela while the salamander moved slowly over the rock surface. No handling was performed and the initial contact between the two animals was not observed. The event therefore cannot be interpreted unambiguously, but may represent opportunistic phoresy or defensive attachment following a failed predation attempt. To our knowledge, this is the first published observation of a ...

Riparian spiders make pyriform silk attachment discs that stick better when wet

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Riparian spiders make pyriform silk attachment discs that stick better when wet

Adhesion in wet conditions presents significant challenges due to the disruptive effects of water on interfacial bonding, spreading, and curing. Many organisms have evolved adhesives that adhere strongly in damp or submerged environments. However, the pyriform silk attachment discs of the western black widow spider lose ∼8x of their adhesive strength when wet. Here, we test the hypothesis that riparian species of spiders have evolved attachment discs that are resistant to water's adverse effects on adhesion. We compare adhesion of attachment discs from three terrestrial, relatively dry habitats to three riparian spider species when discs are loaded under both dry and wet conditions. Failure modes shifted from dragline breakage in dry conditions to adhesive failure in wet conditions across all species, highlighting water's impact on interfacial bonding. However, riparian species attachment discs maintained adhesive force when wet while terrestrial species experienced ∼50% reductions in peak force and work of adhesion in wet conditions. These findings suggest that riparian spider silks have evolved specializations that maintain adhesive performance of pyriform attachment disks in wet environments, offering insights into bioinspired design for water-resistant adhesives.

Bernd F. Steklis, Todd A. Blackledge; Riparian spiders make pyriform silk attachment discs that stick better when wet. J Exp Biol 2025; jeb.250902. doi: https://doi.org/10.1242/jeb.250902