Cave Spiders: Behavioural Adaptations in Webs, Foraging and Dispersal

Posted byKeiron Derek BrownPosted inBlog, entoLIVE BlogTags:, , , , , , , , , , , , , ,

Web-building spiders are excellent model organisms to study the behavioural adaptations to novel habitats such as the dark and food-limited subterranean cave habitat. Cave-dwelling orb spiders in the genus Meta show several potential behavioural adaptations in both their webs (which do not have the typical frame of non-cave orb spiders) and their foraging and dispersal behaviour. Thomas will explore some of the things we do know about these fascinating spiders as well as discuss some of the many things we still do not know.

Q&A with Dr Thomas Hesselberg

Dr Thomas Hesselberg is a lecturer at the Oxford University Department for Continuing Education where he directs the department’s online PgCert in Ecological Survey Techniques. His research is on the behavioural ecology of insects and spiders with a focus on web-building behaviour in orb spiders. Recently he has developed an interest in how spiders adapt their webs to different habitats including to islands, cities and caves.

  1. How is a lack of pigment connected to a lack of light?
    The theory is that a lack of pigment is due to the species not needing to be colourful in a dark environment, and this is the same for loss of eyes in cave organisms. One hypothesis is that this is due to neutral selection, i.e. they are not needed so they will slowly disappear over generations. An alternative hypothesis, which I favour, is that production of pigment has a cost and loss of pigment is actively selected against to conserve resources. 
  2. What is the biggest cave orb web spider?
    Meta menardi that we have in the UK is one of the biggest Meta species that we know of. They are relatively large compared to most species of spiders found in the UK, and just a little smaller than the largest species of house spider and the fen raft spider.
  3. Have you noticed changes to cave spiders or cave environments during your time researching cave spiders?
    There are some really interesting examples of caves being impacted by climate change. Changes are likely to be delayed in comparison to above-ground environments as caves are isolated from external environments to some degree. However, the average temperature of a cave will be linked to the average temperature outside the cave so over time changes will occur and there is likely to be an impact. I’ve only been studying cave spiders since 2018 so it is not something that I’ve personally observed within my research, but cave spiders seem to be doing ok within the UK and we’re not aware of the same declines that we are seeing in other invertebrate groups. However, we have relatively limited data for cave spiders and we’re not yet even at the point where we can assign accurate conservation statuses to them in the UK or elsewhere.
  4. Does the inclination (how vertically-orientated they are) of the webs differ in caves?
    That’s a very interesting question. We have looked at this to see if there are differences as you get further into the cave and the hunting method changes. We’ve not observed any differences, but we need to look more closely at winter versus summer webs as the numbers of crawling prey show seasonal differences. Watch this space!
  5. Do you use a specific frequency when using tuning forks to stimulate the spider’s prey capture response?
    We typically use 128 hertz to simulate a larger prey and 440 hertz to stimulate smaller prey to try and match the wingbeat frequency of prey as they attempt to free themselves from the web. However, our cave spiders to seem to react to almost all frequencies. In aboveground spiders, we have found that they are more likely to attack with higher frequencies and more hesitant with lower frequencies which would indicate a larger and more risky prey.
  6. How should we report records of cave spiders?
    We use records from the British Arachnological Society to look at the distributions of species and what habitats they are being found within. If you are interested in recording cave spiders (or any species of spider), it is worth checking out the Spider Recording Scheme website for guidance on how to record spiders and submit your records.

Literature References

  1. Barrentes & Eberhard (2012) Extreme behavioral adjustments by an orb-web spider to restricted space: https://doi.org/10.1111/j.1439-0310.2012.02029.x
  2. Buchli (1969) Hunting behaviour in the Ctenizidae: https://doi.org/10.1093/icb/9.1.175
  3. Culver & Pipan (2009) The Biology of Caves and Other Subterranean Habitats: https://academic.oup.com/book/34995
  4. Hesselberg et al (2019)  Do cave orb spiders show unique behavioural adaptations to subterranean life? A review of the evidence: https://brill.com/view/journals/beh/156/10/article-p969_1.xml?language=en
  5. Howarth & Moldovan (2018) The ecological classification of cave animals and their adaptations: https://link.springer.com/chapter/10.1007/978-3-319-98852-8_4
  6. Lunghi et al (2024) Behavioural adjustments enable the colonization of subterranean environments: https://doi.org/10.1093/zoolinnean/zlad133
  7. Mammola (2019) Finding answers in the dark: Caves as models in ecology fifty years after Poulson and White: https://nsojournals.onlinelibrary.wiley.com/doi/abs/10.1111/ecog.03905
  8. Mammola & Isaia (2014) Niche differentiation in Meta bourneti and M. menardi (Aranea,Tetragnathidae) with notes on the life history: https://digitalcommons.usf.edu/ijs/vol43/iss3/11/
  9. Simonsen & Hesselberg (2021) Unique behavioural modifications in the web structure of the cave orb spider Meta menardi (Aranaea, Tetragnathidae): https://www.nature.com/articles/s41598-020-79868-w
  10. Smithers (2005)The early life history and dispersal of the cave spider Meta menardi Latreille,1804)(Araneae:Tetragnathidae): https://britishspiders.org.uk/system/files/library/130605.pdf
  11. Tew & Hesselberg (2017) The effect of wind exposure on the web characteristics of a tetragnathid orb spider: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5488162/

Further Info

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Published by Keiron Derek Brown

A blog about biological recording in the UK from the scheme organiser for the National Earthworm Recording Scheme.

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