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Archive for September 27, 2013

Spider Spinnerets

9-30-13 black and yellow sp. spinnerets2 IMG_4897Responses to yesterday’s Mystery Photo ranged from immediate deletion by a reader (due to the unappealing nature of the photo), to guesses including “bee butt,” “caterpillar mouthparts” and “deer tick.” Most responders, however, guessed correctly – the photograph was of the spinnerets of a Black-and-Yellow Garden Spider, Argiope aurantia.

Most spiders have six spinnerets — organs located on their abdomens from which silk is extruded. The individual spinnerets move independently yet in a highly coordinated manner. Each spinneret is dotted with many tiny spigots, through which various types and thicknesses of silk are extruded. The strong muscles that move the spinnerets also force liquid silk through the narrow spigots. This pressure, as well as external pulling by the spider, rearranges the liquid silk molecules into a solid but flexible thread. Although spider web silk is only about one millionth of an inch thick, weight for weight, it is stronger than steel (but not as strong as Kevlar). Unlike in the Mystery Photo, the spinnerets in this photograph are extruded and in use.

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