I am equally disgusted and fascinated by the "Silverfish" (Lepisma saccharina) that we regularly find in our UK home. I tried searching for information on the internet but they seem poorly understood.

We only ever find them on the work surface in the kitchen when we switch on a light at night. They are presumably feeding off food residues - but they never seem to be found in the most obvious place, among the crumbs under the toaster.

When caught by the lights, they run for cover but never, ever climb. You would think them unable to climb at all but then how have they reached the work surface?

The other day there appeared a new twist; 2 "husks" hanging from silk threads between 2 containers, maybe 8cm from the surface. If they were caught and eaten by a spider, why did it take them to a rudimentary web when it (presumably) caught them on the surface? There was no sign of a spider around. The only other possibility I can see is that they somehow suspended THEMSELVES from the silk and this was a moulting behaviour. Thus they now CAN climb - and very well - and also produce silk! Can anyone explain the mystery?

  • $\begingroup$ Hi. Is your question: "What is the function of silk in Silverfish?" (I didn't know they could produce silk). $\endgroup$ – Remi.b Mar 24 '15 at 12:54
  • $\begingroup$ @Remi.b - I think POs title question should be "Can silverfish climb and produce silk?" $\endgroup$ – AliceD Mar 24 '15 at 13:03
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    $\begingroup$ Modified question title, feel free to rollback if it doesn't match what you are trying to ask. Also, a photo of the aforementioned "husks" would be helpful. $\endgroup$ – March Ho Mar 24 '15 at 13:03
  • $\begingroup$ You read my mind @MarchHo $\endgroup$ – AliceD Mar 24 '15 at 13:04

According to a paper by Walker et al. (2013) (found by googling "silverfish + silk", so not very hard to come by), silverfish can indeed produce silk. The paper also mentions that silverfish (Thysanura) and bristletails (Archaeognatha) use silk to transfer their sperm, and they also use it for "...tactile cue during courtship (Sturm, 1956)". This webpage (from NY State University) explains that male silverfish will deposit a spermatophore on a silk thread that is vertically suspended, and the spermatophore is later picked up by a female.

Silks are semi-crystalline solids in which protein chains are associated by intermolecular hydrogen bonding within ordered crystallites, and by entanglement within unordered regions. By varying the type of protein secondary structure within crystallites and the overall degree of molecular order within fibers, arthropods produce fibers with a variety of physical properties suited to many purposes. We characterized silk produced as a tactile stimulus during mating by the grey silverfish (Ctenolepisma longicaudata) using Fourier transform infrared spectroscopy, polarized Raman spectroscopy, gel electrophoresis and amino acid analysis. Fibers were proteinaceous-the main component being a 220 kDa protein-and were rich in Gln/Glu, Leu, and Lys. The protein structure present was predominantly random coil, with a lesser amount of beta-structure. Silk fibers could readily be solubilized in aqueous solutions of a mild chaotrope, sodium dodecyl sulfate, indicating protein chains were not cross-linked by disulfide or other covalent bonds. We conclude that entanglement is the major mechanism by which these silk proteins cohere into a solid material. We propose silks used as short-term tactile cues are subject to less stringent requirements for molecular order relative to other silks, allowing the random coil structure to be favored as an adaptation promoting maximal entanglement and adhesion.

The linked paper contains several references that should be useful if you want to look deeper into how silverfish use silk.

From what I've seen, they don't use silk for climbing. Silverfish can usually climb rough surfaces, but not smooth surfaces, which is why they are often found trapped in sinks, bathtubs etc.

  • $\begingroup$ This species seems to be different to the one we have in the UK and is more an American variant according to Wikipedia. However, it seems strange that a species would develop silk glands simply for such an undefined function - even one related to reproduction. $\endgroup$ – Lefty Mar 24 '15 at 14:41
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    $\begingroup$ @Lefty Since the paper seems to claim that the ability of produce silk covers the entire order of Thysanura (along with bristletails, spiders etc), it is unlikley to be specific to their particular study species. To use silk for courtship and sperm transfer is hardly "undefined", since reproduction is essential in the life history of a species. $\endgroup$ – fileunderwater Mar 24 '15 at 14:44
  • $\begingroup$ No, these papers are more interested in the structure of the silk, not the lifestyle of the Silverfish. The only thing it does is to confirm that they do indeed produce silk for the purpose of reproduction - although to transfer sperm packets, not as a "tactile stimulus" in your extract. I'm interested in their reluctance to climb and whether the silk is used in the moulting process. $\endgroup$ – Lefty Mar 24 '15 at 17:27
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    $\begingroup$ @Lefty in that case, please edit your question so the actual question being asked is clearer. $\endgroup$ – terdon Mar 24 '15 at 18:59
  • $\begingroup$ It seems pretty clear to me, just read the question text rather than the title. $\endgroup$ – Lefty Mar 24 '15 at 20:01

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