Do spiders have a sense that can detect the presence of water?
I often find Hololena spiders (an outdoor variety) trapped in my bathtub or kitchen sink, unable to climb back out over the slippery surface. Do they get there by accident, or are they attracted to them by the presence of moisture?
Thanks for your response,
Spokane County Washington spiders
Thanks for contacting us with your question.
There is a great deal of information and misinformation out there, so this represents the best of what I've found. It may not be the last word on "spider-sense" however, so I encourage you to keep researching a fascinating subject.
Depending on the species and environment, spiders may get most of their water through their prey, but as you mentioned, they also drink water, particularly in dry environments, or if prey is scarce. In the wild, they will drink water droplets from vegetation, from sources like puddles, or from dew drop on their webs.
In our houses during the winter, spiders move around searching for prey, water, and male spiders will look for a mate. If they find a water source such as a sink or bathtub, they move toward the source, usually the drain. They often become trapped because they cannot climb the slick surfaces, and because they are trapped we encounter them there more often than in other parts of the home where they can run away.
Spiders don't have a special sense that tells them where to look for water, but they are able to detect it. They have sensory organs on their legs that are analogous to our senses of taste and smell, although this is an inexact comparison. If these sensors detect water, the spiders will move toward it. Other organs. including the hair on their legs, allow them to pick up vibrations. They seem to be able to interpret these vibrations, for instance rain hitting their web, vs. the vibrations of prey, or the deliberate 'web-strumming' of a potential mate.
If you relocated the spiders to your basement, they would search for prey, water and possibly a mate, until they found it or died. This might mean they would come back upstairs, find a way outdoors, or stay there if their basic needs were met. I could not find a source for how far away a spider can detect water. Anecdotally, some people that keep them as pets report that the spiders easily find water sources in their habitat.
I hope this helps answer your questions. Thanks again for contacting us!
I think a radio tag study would teach us a lot, and I would like to know where they go all the time. Short of that, I think you have a good plan. I know they will be happier outside when the weather warms and they can eat all the bad bugs they can find.