I***i
发帖数: 14557 | 1 http://www.newscientist.com/blogs/shortsharpscience/2012/12/spi
Spider builds giant decoy of itself
(Image: Phil Torres)
Hanging out in the jungles of Peru can be a dangerous pastime for a spider -
how do you dodge predators while casting your web in the open? A newly
spied type of Cyclosa spider has come up with a solution - hide behind a
giant, fake version of yourself.
Naturalist Phil Torres describes how he spotted the spider bodyguard while
trekking near the Tambopata Research Center in Peru.
"From afar, it appears to be a medium-sized spider about an inch across,
possibly dead and dried out, hanging in the centre of a spider web along the
side of the trail," he says. "Step in even closer and things start to get
weird - that spider form you were looking at is actually made up of tiny
bits of leaf, debris and dead insects."
Upon closer examination, Torres spotted a tiny, 5-millimetre spider hiding
behind its doppelganger.
Cyclosa mulmeinensis is already known to build decoy objects on its web, but
these tend to look like blob-like prey pellets and egg sacs. The newly
described decoys look more like a spider, complete with eight dangly legs.
To build their body doubles, the spiders gather leaf fragments, plant parts,
prey remains, egg sacs and other handy detritus. Then they arrange the
debris along specialised silk strands called stabilimenta to create the
shape and legs.
The results of such decoys are counter-intuitive - surely it's like covering
yourself in a giant fake steak before parading in front of the local lion
pride? But although such decoys tend to attract predators to webs by making
them more conspicuous, they may draw away enough attacks from the spider
itself to make them worthwhile.
Torres says that some Cyclosa species have a higher survival rate against
potential predators, such as paper wasps, because the wasps attack the
highly visible debris in the web rather than the spider itself.
Torres hopes to collaborate with spider specialists to determine if the
arachnid's unique behaviour could indicate the discovery of a new species of
Cyclosa. | I***i
发帖数: 14557 | 2 http://blogs.smithsonianmag.com/smartnews/2012/12/spider-builds
Spider Builds Fake Spider Decoy
Deep in the Peruvian Amazon, a spider is at work building an elaborate, fake
decoy of itself. In its web, it busily goes to working crafting its doppelg
änger out of leaves, debris and dead prey insects, including multiple
spidery legs, a head and abdomen, Wired reports.
The new spider, thought to be a member of the genus Cyclosa, might build
these decoys as part of a defense mechanism to confuse or distract predators
. Spiders already make impressive geometric webs, scientists reason, so
building other designs isn’t such a leap.
Researchers exploring a floodplain in the forest first learned of the spider
when the spotted what they thought was a dead spider caught in a web. It
looked flaky, writes Wired, like a fungus-covered arthropod corpse. But the
would-be corpse began twitching, and then the researchers noticed a second,
smaller spider about an inch above the decoy, shaking her web. The
researchers said it “blew their minds.”
Arachnologists soon confirmed that the finding was unique, though more field
observations will be needed before the specimen can be confirmed as a new
species to science. Other members of Cyclosa are known for building decoys,
but those already known to science tend to be clumpy and not nearly as
anatomically precise as these examples.
So far, the research team has found around 25 of the clever little spiders.
They have no idea if the species is locally restricted or found for miles
within the forest. For now, however, the spider mission is on hold. The
researchers lack the necessary permits to collect more animals, so until
that paperwork comes through in January, arachnologists will be holding
their breath. | i*****s
发帖数: 15215 | | e****o
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