Knowra Evolution of spiders Evolution of spiders The evolutionary history of spiders traces their origin from arachnid ancestors, their diversification into major lineages, and the development of traits such as silk production and specialized venom.
Arachnid : An arthropod in the subphylum Chelicerata, including spiders, scorpions, mites, and harvestmen. Spiders evolved within this broader group of eight-legged chelicerates.
Spinneret : A spider appendage that extrudes silk from glands through tiny outlets called spigots. Spinnerets are the specialized structures that distinguish spider silk systems from earlier silk-producing forms.
Megarachne servinei : A large Carboniferous fossil initially interpreted as a giant spider, later identified as a eurypterid. Its reclassification illustrates how fragmentary fossils can distort reconstructions of spider history.
Orb web : A roughly circular capture web made of radial and spiral silk lines by many spiders. Orb webs show how specialized silk architecture evolved as a prey-capture strategy.
Uraraneida : An extinct group of Paleozoic arachnids with silk-producing structures but no true spider spinnerets. These fossils illuminate forms close to the origin of spiders and silk use.
Spider silk : A protein fiber produced by spiders, with properties suited to webs, draglines, egg cases, and other uses. Its diverse roles have shaped spider behavior and ecological opportunities.
Mesothelae : A living spider suborder whose members retain segmented abdomens and posteriorly placed spinnerets. These spiders preserve features that help compare early-diverging lineages with more derived spiders.
Spider web : A structure made from spider silk, used for prey capture, shelter, reproduction, or movement. Webs are among the most visible outcomes of silk's evolutionary diversification.
Attercopus : An extinct Permian arachnid genus known from fossils bearing silk-producing structures but lacking modern spinnerets. Its fossils provide early evidence of silk production before modern spider anatomy appeared.
Chelicera : A paired anterior appendage in chelicerates, modified in spiders into fangs and associated structures. Spider chelicerae house or support the venom-delivery apparatus central to prey capture.
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