Posted on 09/27/2006 7:16:29 PM PDT by PatrickHenry
Discovery could have implications for evolutionary origin of spider silk
Researchers have found for the first time that tarantulas can produce silk from their feet as well as their spinnerets, a discovery with profound implications for why spiders began to spin silk in the first place.
Adam Summers, a UC Irvine assistant professor of ecology and evolutionary biology, was among the team of scientists who made the discovery using zebra tarantulas from Costa Rica. The team found that the tarantulas secrete silk from spigots on their legs, allowing them to better cling to surfaces. Until now, spiders were only known to spin silk from spinnerets located on their abdomen and to use the silk to form webs for protection and capturing prey rather than for locomotion.
The findings are published in the current issue of Nature.
If we find that other spiders in addition to these tarantulas have the ability to secrete silk from their feet, this could represent a major change in our evolutionary hypothesis regarding spider silk, Summers said. It could mean that silk production actually originated in the feet to increase traction, with the diversity of spinneret silk evolving later.
The researchers placed tarantulas on a vertical glass surface. Though ground dwelling, these spiders can normally hang on to vertical surfaces by using thousands of spatulate hairs and small claws. However, the scientists noticed that when the spider started to slip down the surface, it produced silk from all four pairs of legs, allowing it to adhere to the glass for more than 20 minutes. The silk secretions were clearly visible on the glass. Using scanning electron microscopy, the scientists also were able to see the openings on the legs that resemble the silk-producing spigots on spider abdominal spinnerets.
The next step, according to Summers, is to investigate whether the silk produced by the feet is the same as that produced by the spinneret. Many spiders can produce seven different kinds of silk. Scientists will look at the genes involved in silk production from the feet, compare them to the gene family that leads to spinneret silk production, and be able to better determine whether silk was originally used for traction, or whether that was a secondary usage that came later.
Collaborating on the study were Stanislav Gorb of the Max Planck Institute for Metals Research in Germany; Senta Niederegger of the Friedrich Schiller University of Jena in Germany; Cheryl Hayashi of UC Riverside; Walter Votsch of the Max Planck Institute for Developmental Biology in Germany; and Paul Walther of the University of Ulm in Germany.
Well, bless my soul.
If I didn't go and leave out the whole point.
The devotion threads have *strict* enforcement of no flaming, etc.
Hence my "irreverent" vs. "dysgnostic" line.
If we agreed that there would be a similar enforcement of no troll, spamming, etc., on science threads within that Forum, we could have some higher-quality discussion.
OTOH, FWIW, many of the threads by NeverDem or SunkenCiv seem to do fine without harsh moderation--maybe that's because they are on a wide range of topics. Maybe crevo threads are just like waving a flag in front of a bull...? Or in your language, "deny anything that contradicts their religious beliefs."
I wouldn't mind so much if more of them were like [names deleted]. But [other names deleted] seem to repeat the same lines ad infinitum, ad nauseum.
I used to think that it was because they were stubborn, or hadn't read the rejoinders. But lately I am coming to the conclusion that some of them are using their posts (as you implied) as a technique to disrupt the threads.
Such tactics only belong on DU, not on FR.
Cheers!
Those folks are called trolls.
(Good night all.)
Looking at "My Comments" shows that post #2 (my ping to the list) was in "News", and so was #3; but from #3 on it's all in "Chat." I don't know why those two posts show up like that for me, but there they are.
There was no cause at that very early stage to toss this thread into the dumpster, except: (1) the mod doesn't like spiders; (2) the mod doesn't like me; (3) the mod is furious at how many people are voting "No" in the evolution poll; or (4) all of the foregoing.
Becky
Here's another that going up the side of the house last year.
Becky
Had the same thought. So Stan Lee was right.
(Except that SM's webs were a gadget-created in the earliest versions of the genre.)
@
The Magnificent Spider captures its prey by deception At night it spins a short line of silk with a sticky globule of silk at the free end - the bolas. This sticky silk globule may contain pheromones that mimic the scent of a certain female noctuid moth species, attracting unwary male moths within range (known as "aggressive mimicry"). The Magnificent Spider is very sensitive to vibrations, twirling its thread when it senses the approach of a moth's beating wings. The moth eventually flutters close enough to be hit by and become stuck to the globule. The spider then pulls up the strand, bites and immobilises the moth, and either eats it straight away or stores it for later, wrapped in silk. These spiders can also be induced to respond to the vibrations of plucked guitar strings.
Bingo!
You can expect to receive your prize... sometime in the future.
That doesn't explain the tarantula's preference for knee-highs.
<< FR used to be more accommodating to science. >>
The sidebar poll on teaching ID in science classes speaks for itself. FR is no friend to science.
I used to live in W. Tx....so many, Oh, So many.
...like the two-legged Congresscritters.
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