In Memoriam: Giraldo Alayón García

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  In Memoriam: Giraldo Alayón García -  Photo © Facebook/National Museum of Natural History of Cuba In Memoriam: Giraldo Alayón García The arachnological community mourns the loss of Giraldo Alayón García, a Cuban zoologist whose work helped bring the spiders of Cuba and the wider Caribbean into clearer scientific view. As a researcher and curator at Cuba’s National Museum of Natural History, Dr. Alayón devoted decades to studying arachnids. His publications on spider taxonomy, evolution, and biogeography gave other researchers a stronger foundation for understanding the region’s biodiversity. He also shared that knowledge through teaching and scientific exchange far beyond Cuba. For those of us who care about taxonomy, his legacy is a reminder of the patient work behind every species description: examining specimens, recording differences, and preserving knowledge that others can build upon. His contributions will continue to guide the study of Caribbean spiders for years to ...

Changes in the material properties of spider glue droplet proteins accompanied shifts in prey capture biomechanics as cobweb spiders diverged from their orb weaving ancestors

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Changes in the material properties of spider glue droplet proteins accompanied shifts in prey capture biomechanics as cobweb spiders diverged from their orb weaving ancestors

Abstract

Although descended from orb weavers, spiders in the family Theridiidae spin cobwebs whose sticky prey capture gumfoot lines extend from a silk tangle to a surface below. When a crawling insect contacts glue droplets at the bottom of a gumfoot line, the line's weak pyriform anchor releases, causing the taut line to contract, pulling the insect from the surface and making its struggles to escape ineffective. To determine if this change in prey capture biomechanics was accompanied by a change in the material properties of theridiid glue, we characterized the elastic modulus and toughness of the glue droplet proteins of four theridiid species at 20% - 90% relative humidity and compared their properties with those of 13 orb weaving species in the families Tetragnathidae and Araneidae. Compared to orb weavers, theridiid glue proteins had low extensions per protein volume and low elastic modulus and toughness values. These differences are likely explained by the loss of tension on a gumfoot line when its anchor fails, which may prioritize glue droplet adhesion rather than extension. Similarities in theridiid glue droplet properties did not reflect these species’ evolutionary relationships. Instead, they appear associated with differences in web architecture. Two species that had stiffer gumfoot support lines and longer and more closely spaced gumfoot lines also had stiffer glue proteins. These lines may store more energy, and, when their anchors release, require stiffer glue to resist the more forceful upward thrust of a prey.

Opell, B. D., Kelly, S. D., Morris, S. A., & Correa-Garhwal, S. M. (2024). Changes in the material properties of spider glue droplet proteins accompanied shifts in prey capture biomechanics as cobweb spiders diverged from their orb weaving ancestors. Acta Biomaterialia. https://doi.org/10.1016/j.actbio.2024.05.043