Why tarantulas are hairy? Alireza Zamani

Researcher Alireza Zamani, Biodiversity Unit, University of Turku.
Ever wondered why tarantulas are so hairy? Our newest publication offers a new hypothesis.
🟢 Observations and field experiments suggest that predatory ants often ignore burrowing tarantulas and their spiderlings. Instead, ants enter the tarantulas’ burrows only to gather food remains, and in the process clean the spider’s burrow. When ants do try to attack, they struggle to secure a hold due to the spider’s hairiness. This suggests that tarantula hairiness may have evolved partially as a defensive strategy against army ants.
🟢 In rare cases where ants do subdue tarantulas, these tarantulas tend to be less hairy and typically produce more silk in their burrows, creating physical barriers against ants.
🟢 We also documented a unique escape strategy against ants in tree-dwelling tarantulas, which were found hanging from the edge of the vegetation after sensing the approach of the army ants.
🟢 Our hypothesis is further supported by previous findings that urticating hairs on egg sacs and moulting mats serve as barriers against predatory ants and effectively hinder their movement.
🟢 We also discuss the possibility of chemical defenses in tarantulas. This is supported by the observation that when sniffing a live pet tarantula, cats and dogs often quickly wince and move away despite the spider not releasing any urticating hairs or making a threat posture. Tarantulas have slit-like epidermal gland openings of unknown function, that we suggest, might be responsible for causing such reactions.
Video: Hanna Oksanen, University of Turku
Photos: David Hillis, Witold Lapinski, Rick West (2), Emanuele Biggi, Rick West, Rainer Foelix.Zamani, A., West, R. C. & Lamar, W. W. (2024).
An extensive review of mutualistic and similar ecological associations involving tarantulas (Araneae: Theraphosidae), with a new hypothesis on the evolution of their hirsuteness. Journal of Natural History 58(29-32): 1107-1143. www.tandfonlin...
#arachnology #tarantulas #mutualism #evolution #theraphosidae