Darwin Day

February 12, 2011

Tags: Darwin

Charles Darwin was born 202 years ago today.

Although spiders don't figure much in On the Origin of Species, Darwin--an inveterate bug hunter--delighted in their variety and behaviors. He records some of his observations on "Aeronaut Spiders" in The Voyage of the Beagle:

"On several occasions, when the 'Beagle' has been within the mouth of the Plata, the rigging has been coated with the web of the Gossamer Spider. One day (November 1st, 1832) I paid particular attention to this subject. The weather had been fine and clear, and in the morning the air was full of patches of the flocculent web, as on an autumnal day in England. The ship was sixty miles distant from the land, in the direction of a steady though light breeze. Vast numbers of a small spider, about one-tenth of an inch in length, and of a dusky red colour, were attached to the webs...."

You can read on by going to the December 6, 1833, section of Chapter VIII.

Evolution is in the air today.

Hoisting

February 11, 2011

Tags: Olios, Pellenes, Sparassidae, Salticidae

The "conchicolous habit"--hermit crabs have it, some bees and wasps have it, but a few spider species lift shell dwelling to new heights: they use silk to hoist their prefab homes into the air. A BBC crew working in Madagascar has finally caught the efforts of one of these species, Olios coenobitus, on film.



O. coenobitus is in the family Sparassidae, the huntsman spiders. At least one other species, Pellenes nigrociliatus, a jumping spider (family Salticidae), has also been found living in suspended snail shells, in Poland. Neither of these spiders can produce the stretchy silk used in the catching spirals of orb weavers and their descendants. In fact, few spiders in either of these families make any kind of web. Their hoisting ropes consist of major ampullate dragline silk, the super-strong silk araneomorph spiders use to rappel. In the lab, these spiders have been observed to lift shells more than 20 times their own body weight.

It might seem inconceivable that the same strange behavior would evolve in two species of spider that aren't terribly closely related. But it looks strange only to us humans. An empty shell isn't so different from the burrows spiders dig themselves or the crevices in bark they often occupy. And spiders frequently use silk to suspend killed prey and egg sacs. They pull on silk threads all the time to bring them under tension. We'll probably never know exactly how this feat evolved, but many spiders already had the tools and behaviors needed to accomplish it. Looked at that way, it's surprising this behavior hasn't evolved more often. But then again, even these spiders' closest relatives get along fine without it. In evolution, "good enough" is good enough.

Read how the film was made here.

Recent Reviews

February 5, 2011

Tags: reviews

We're thrilled with the most recent reviews of Spider Silk from BioScience, the Quarterly Review of Biology, and Choice, the leading review journal for academic librarians. Choice deemed Spider Silk an "Editor's Pick," calling it "wonderfully entertaining." Please take a look at excerpts from these reviews at our press/links page.




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"...a compelling introduction to evolution in action through the lens of spiders and their silks."

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