Cribellum

For other uses, see Cribellum (disambiguation).

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 get away.

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 found out that there are many families with both cribellate and ecribellate members (Lehtinen, 1967). It is today 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).

Only about 180 genera in 23 families (1991) still contain cribellate members, although the diverse Australian cribellate fauna is still mostly undescribed. However, that fauna may be an example of high diversity in Australian animals that are only relicts in other regions of the world, like the marsupials (Coddington & Levy, 1991).

Cribellate taxa are not very speciose, and for nearly all cribellate-ecribellate sister clades the cribellate lineage is less diverse (Coddington & Levy, 1991), for example:

• Haplogynae: cribellate Filistatidae ca. 100 species, all others (mostly ecribellate): ca. 3,000 species
• Uloboroidea ca. 320 species, Araneoidea: ca. 11,000 species

Cribellate families

22 families of araneomorph spiders (Agelenidae, Amaurobiidae, Amphinectidae, Austrochilidae, Ctenidae, Deinopidae, Desidae, Dictynidae, Eresidae, Filistatidae, Gradungulidae, Hypochilidae, Miturgidae, Neolanidae, Nicodamidae, Oecobiidae, Psechridae, Stiphidiidae, Tengellidae, Titanoecidae, Uloboridae, Zoropsidae) contain at least some cribellate spiders (Griswold et al. 1999). While some of these families are entirely cribellate, others contain both cribellate and ecribellate species.

Diatom cribellum

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

References

1. ^ Foelix, Rainer F. (1996). Biology of Spiders (2 ed.). Oxford University Press. p. 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. 

• Lehtinen, P.T. (1967). Classification of the Cribellate spiders and some allied families, with notes on the evolution of the suborder Araneomorpha. Ann. Zool. Fennici 4: 199-467.
• Foelix, Rainer F. 1979. Biologie der Spinnen. Georg Thieme Verlag Stuttgart. ISBN 313575801x
• Coddington, J.A. & Levi, H.W. (1991). Systematics and Evolution of Spiders (Araneae). Annu. Rev. Ecol. Syst. 22: 565-592.
• Eberhard, William G. and Pereira, Flory. 1993. Ultrastructure of cribellate silk of nine species in eight families and possible taxonomic implications (Araneae: Amaurobiidae, Deinopidae, Desidae, Dictynidae, Filistatidae, Hypochilidae, Stiphidiidae, Tengellidae). Journal of Arachnology 21(3): 161-174. PDF
• Huber, B.A. (1994): Spermophore morphology reveals a new synapomorphy of Oecobius and Uroctea (Araneae, Oecobiidae). Journal of Arachnology 22: 73-74. PDF
• Griswold, C.E., Coddington, J.A., Platnick, N.I. and Forster, R.R. (1999). Towards a Phylogeny of Entelegyne Spiders (Araneae, Araneomorphae, Entelegynae). Journal of Arachnology 27: 53-63. PDF

External links

• The Spider - Web and Silk (description and pictures)
• Cribellate silk vs. sticky silk
• The Evolution of Web Usage in Spiders

This spider–related article is a stub. You can help Wikipedia by expanding it.v · Categories: Spider anatomy Spider stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать курсовую Jesse Fell Beten (mythology) Look at other dictionaries: cribellum — ● cribellum, cribella ou cribellums nom masculin (latin cribellum, petit crible) Plaque criblée des araignées cribellates, située en avant des filières, et par où sort une soie gommeuse, étirée par les calamistra en fils destinés à retenir les… …   Encyclopédie Universelle Cribellum — Cri*bel lum (kr?b?l l?m), n. [L., a small sieve, dim. of cribrum sieve.] (Zo[ o]l.) A peculiar perforated organ of certain spiders ({Ciniflonid[ae]}), used for spinning a special kind of silk. [1913 Webster] …   The Collaborative International Dictionary of English Cribellum — Cribellate Spinnen (Cribellatae) sind Echte Webspinnen, die dank besonderer Organe in der Lage sind, Fangwolle ohne Leimtröpfchen für ihre Spinnennetze herzustellen. Sie unterscheiden sich grundlegend von den ecribellaten Spinnen, die Leimfäden… …   Deutsch Wikipedia cribellum — n. [L. cribrum, sieve] 1. (ARTHROPODA: Chelicerata) In spiders, a sieve like, transverse plate, usually divided by a delicate keel into two equal parts, located in front of the spinnerets; the modified anterior median spinnerets. 2. (ARTHROPODA:… …   Dictionary of invertebrate zoology cribellum — noun /kɹɪˈbɛləm/ A spinning organ having many fine pores, situated in front of the spinners in some spiders …   Wiktionary cribellum — [krɪ bɛləm] noun (plural cribella lə) Zoology (in some spiders) an additional spinning organ with numerous fine pores, situated in front of the spinnerets. Derivatives cribellate adjective Origin C19: from late L., dimin. of cribrum sieve …   English new terms dictionary cribellum — cri·bel·lum …   English syllables cribellum — …   Useful english dictionary Cribrarula cribellum — Scientific classification Kingdom: Animalia Phylum: Mollusca Class: G …   Wikipedia posterior cribellum — (ARTHROPODA: Chelicerata) In Arachnida, the posterolateral spinnerets in Stenochilidae …   Dictionary of invertebrate zoology 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”