Although spiders are inevitably known for their capacity to spindle a silk web to catch prey, they apparently can release silk from their feet as well in order to maintain a grip on slippery surfaces. The spiders that are able to use this mechanism are tarantulas, specially the Chilean rose tarantula.
Biologist Claire Rind and her colleagues have studied spiders at Newcastle University and their most recent discovery, silk from feet, has left arachnologists from all over astounded that spiders can release silk from other ligaments of the body, not just the abdominal spinnerets. Tarantulas are simply too heavy to just rely on sticky foot hairs to keep their grip when they are climbing as other spiders do.
In order for tarantulas to release the silk from their feet, their body has to be vertical. Rind and her colleagues experimented with the spiders by observing their climbing behavior on slippery surfaces. The tarantula that was being studied was placed in a glass box lined with microscope slides. Then, the box was shaken around in order to ensure the spider to lose its grip. The spider was slipping on the glass but then maintained its grip and was able to hang on. The only part to touch the microscope slide was the feet of the Chilean rose because the slides had silk footprints that were observed under the microscope. To ensure that this phenomenon was correct, Rind also evaluated the molten exoskeleton where silk traces were identified. The spinnerets in the feet looked like nozzles among the setae.
Rind plans to continue her research and eventually discover if any other spider species are capable of secreting silk from their feet just as the Chilean rose does. She also hopes to distinguish if any other ligaments of the spider can use the same mechanism as the feet and the abdominal spinneret.
Berlin, J. Spider spigots. National Geographic. November 2011, Vol 220 Issue 5, page 25.
That is interesting; I did not know any spiders were capable of producing silk from their feet. It makes sense a heave spider would need the extra grip. The spider silk title caught my attention because I know the silk is actually very valuable for many uses. It actually has the tensile strength per square inch comparable to steel and is light weight and flexible. Potential uses are bullet proof amour protection, artificial ligaments, sutures, structures, vehicles, and others. The military spent tons of money on research and a farm in Canada can actually implement spider genes into goats. When female goats lactate, the mammary glands will actually produce spider silk. The experiment was a semi-success and the goats can produce the silk proteins and material, but unfortunately can not “spin” the silk like spiders so the silk material produced by goats is essentially useless for applications until this problem is solved (http://liz1812.tripod.com/gmgoats/id2.html).
ReplyDeleteThis article was interesting to me more for their testing method than the basic idea that some spiders are capable of producing silk from extremities.
ReplyDeleteI thought the box lined with microscope slides was an interesting twist to better enable them to focus on the distinct foot patterns of the spider. Knowing the silk extensions came from the feet but figuring out a way to adequately test it was interesting. The glass box allowed them to witness the silk extensions while collecting samples to observe later.
But I wondered why they looked at the molted exoskeleton of the Chilean rose in addition to the silk footprints if they knew it was capable of extending silk extensions for webbing from its abdominal spinnerets? It seems that silk traces would be obvious on the general exoskeleton with this capability. It seems that the only reason would be segments of the exoskeleton are hinged to allow ligament movement and the silk projections from the feet and the abdominal would be similar if the spider was actually capable of producing silk from their feet.
This is a very interesting blog post!
ReplyDeleteI am deathly afraid of spiders because I have a very adverse affect to spider bites (at least the few I have had to deal with, thankfully)
However, I wonder if they looked at Chilean rose spider in different climates, and observed whether or not the spider lost their grip. It would be interesting to see if the glass was cooler or warmer if it had an effect on how well, or how long the spider could hold on.
Also, is the web that comes out of the feet similar to the web that is released from the abdomen? Or is it perhaps the same web released only from there feet and then led down their abdomen? I wonder if the web from the spider's feet has something to do with the web spinning process. It is fascinating to think that a spider is able to release such a powerful substance for gripping and catching their prey.