Seta

For other uses, see Seta (disambiguation).

Setae on the toes of a gecko

Seta (plural: setae) is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.

Animal setae

In zoology, most "setae" occur in invertebrates.

• Setae in annelids are stiff bristles present on the body. They help for example earthworms to attach to the surface and prevent backsliding during peristaltic motion. These hairs are what make it difficult to pull a worm straight from the ground. Setae in oligochaetes (a group including earthworms) are largely composed of chitin.^[1] They are classified according to the limb to which they are attached; for instance, notosetae are attached to notopodia; neurosetae to neuropodia.^[2]
• Setae on the legs of krill and other small crustaceans help them to gather phytoplankton.
• Setae in entomology are often called hairs or chaetae. They are unicellular and formed by the outgrowth of a single epidermal cell (trichogen). They are generally hollow and project through a secondary or accessory (tormogen) cell as it develops. The setal membrane is not cuticularized and movement is possible. This serves to protect the body.
• Setae on gecko footpads are small hair-like processes responsible for the animal's ability to cling to vertical surfaces.

Fungal setae

In mycology, "setae" refer to dark brown, thick-walled, thorn-like cystidia found in corticioid and poroid fungi in the family Hymenochaetaceae.^[3] Though mainly microscopic, the setae of some species may be sufficiently prominent to be visible with a hand lens.

Plant setae

In botany, "seta" refers to the stalk supporting the capsule of a moss, hornwort or liverwort, and supplying it with nutrients. The seta is part of the sporophyte and has a short foot embedded in the gametophyte on which it is parasitic. Setae are not present in all mosses, but in some species they may reach 15 to 20 centimeters in height.^[4]

Artificial setae

The development of adhesives that detach at will yet display substantial stickiness is of great importance for various technological fields.^[5][6]

See also

• Chaeta
• Synthetic setae
• Van der Waals force

References

1. ^ Hyman, H.L. (1966) "Further Notes on the Occurrence of Chitin in Invertebrates" Biological Bulletin, 130: 1-149. http://www.biolbull.org/cgi/reprint/130/1/94.pdf
2. ^ Butterfield, N. J. (1990). "A Reassessment of the Enigmatic Burgess Shale Fossil Wiwaxia corrugata (Matthew) and Its Relationship to the Polychaete Canadia spinosa Walcott". Paleobiology 16 (3): 287–303. doi:10.2307/2400789. JSTOR 2400789.  edit
3. ^ Kirk PM, Cannon PF, Minter DW, Stalpers JA. (2008). Dictionary of the Fungi (10th ed.). Wallingford: CABI. p. 116. ISBN 978-0-85199-826-8. 
4. ^ Raven, Peter H.; Evert, R.F. & Eichhorn, S.E. (2005): Biology of Plants (7th ed.). W.H. Freeman and Company.
5. ^ Engineers create new adhesive that mimics gecko toe hairs Physorg.com Jan 29, 2008
6. ^ Setae Research