http://www.collembola.org/doc/furcae.htm - Last updated on 2010.01.25 by Frans Janssens
Checklist of the Collembola: Furcae

Components of the furca

The furca comprises a basal segment, the manubrium, provided apically with two arms, the dentes. Each dens terminates in an apical segment, the mucro.


Dicyrtomina saundersi, ventral aspect, furca in unlocked, extended position
Krebs, C. © 2007.

Positions of the furca
Orchesella cincta, ventral aspect,
furca in locked position
Hall, K. © 2005.

Entomobrya intermedia, ventral aspect,
furca in locked position
Valentine, B. © 2007.11.30.

Dicyrtomina saundersi, ventral aspect,
furca in locked position
Valentine, B. © 2008.11.24
In this postion, the furca is 'spring loaded' and held in place by the retinaculum, ready to 'fire off'. When released by the retinaculum, the furca will hit the substrate and project the animal into the air.
 


Dicyrtoma fusca, ventral aspect, furca in unlocked, extended position
Hall, K. © 2005.
In this postion, the furca has been released by the retinaculum and the furca has been swinged backwards. During the jump in the air, the furca is normally brought back in forward position by strong longitudinal abdominal muscles, up to the point it is relocked by the retinaculum, reloading the furca as such effectively for a new jump.


Dicyrtoma saundersi, furca in unlocked, extended position
Baas, A.H. © 2007.11.22.
The furca is extended due to exhausting of the specimen, e.g. after a series of jumps.
 
 
 
 
 

Tetrodontophora bielanensis,
furca in locked position
Deml, M. © 2008.04.21.
The furca is locked in place by the retinaculum.