Unless you see the spider, which is unlikely, you won't be able to tell exactly who spun that web.
In this moment, you really only want to know two things: “IS IT ON ME?!” and “WHAT KIND OF SPIDER WAS THAT?!” And if you walk into one, you instantly become a karate master. The glob of silk that binds or anchors strands emerges from the spigot as a liquid.Spider webs are intricate marvels of engineering, beautiful and strong. Strands usually are flat or cylindrical as they emerge and are of surprisingly uniform diameter.
Silk probably changes to a solid in the spigot or as a result of tension forces. Threads of silk from the orb weaver Nephila have a high tensile strength and great elasticity. Silk may have evolved from an excretory product. Epigastric silk glands of male spiders produce silk that emerges through spigots in the abdomen between the book lung covers and provides a surface for the sperm to be deposited upon during sperm induction. Primitive spiders (suborder Mesothelae) have only two types of silk glands, but orb weavers have at least seven, each of which produces a different kind of silk e.g., aciniform glands produce silk for wrapping prey, ampullate glands produce the draglines and frame threads, and cylindrical glands produce parts of the egg sac. Abdominal pressure forces the silk to flow outward, although the rate of flow is controlled by muscular valves in the ducts. Ducts from the glands traverse structures called spinnerets, which open to the outside through spigots. The silk is produced by different types of glands in the abdomen.
Spider silks that have been studied are proteins called fibroin, which has chemical characteristics similar to those of insect silk. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Īlthough silk is produced by some insects, centipedes, and millipedes and a similar substance is produced by mites, pseudoscorpions, and some crustaceans (ostracods and amphipods), only the spiders are true silk specialists.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
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