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Progradungula otwayensis (Gradungulidae) holding a snare made from silk spun from its cribellum

The cribellum is a silk spinning organ found in certain spiders. Unlike normal spinnerets, the cribellum consists of one or more plates covered in thousands of tiny spigots.[1] These spigots produce extremely fine fibers which are combed out by the spider's calamistrum, producing silk with a wooly texture. The fibers are so small in diameter that prey insects easily become entangled in them, without any glue needed. The spiders then bite them before they can escape.

The cribellum is a functional homolog of the anterior median spinnerets of Mesothelae and Mygalomorphae, which do not have a cribellum.

The presence or absence of a cribellum is used to classify araneomorph spiders into the cribellate and ecribellate (not cribellate) type. The distinction can be used to study evolutionary relationships. However, in 1967 it was discovered that there are many families with both cribellate and ecribellate members (Lehtinen, 1967). Today, it is believed that the precursor of all Araneomorphae was cribellate (symplesiomorphy), and that this function was lost in some araneomorph spiders secondarily (Coddington & Levy, 1991). Many of these still retain a colulus, which is thought to be a reduced cribellum, and is of unknown function. However, some "ecribellate" spiders seem to have evolved independently, without cribellate precursors (Foelix, 1979).



Cribellate families[edit]


Diatom cribellum[edit]

The outside layer of a diatom is also called a cribellum. It consists of a thin siliceous membrane covered with small pores.[2]


  1. ^ Foelix, Rainer F. (1996). Biology of Spiders (2 ed.). Oxford University Press. pp. 118–122. 
  2. ^ Gordon, Richard; Dusan Losic; Mary Ann Tiffany; Stephen S. Nagy; Frithjof A.S. Sterrenburg (February 2009). "The Glass Menagerie: diatoms for novel applications in nanotechnology". Trends in Biotechnology 27 (2): 116–27. doi:10.1016/j.tibtech.2008.11.003. PMID 19167770. 
  • Foelix, Rainer F. 1979. Biologie der Spinnen. Georg Thieme Verlag Stuttgart. ISBN 3-13-575801-X

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