http://www.collembola.org/slides/setaea04.htm - Last updated on 2001.09.05 by Frans Janssens

Fig.4. Setae with a negative shaft diameter gradient. Janssens, F. © 1999.

Negative proximodistal shaft diameter gradient The negative proximodistal gradient of the diameter of the shaft can be linear or non-linear. A linear gradient results in a conic shaft profile. A non-linear gradient produces a curved shaft profile. A negative curvature produces the biconcave shaft profile of the more narrowing threadlike (filiform) setae. A positive curvature makes the biconvex shaft profile of the more broadening spinelike (spiniform) setae.