Morphology and function of the forelimb in arboreal frogs: specializations for grasping ability?
Article first published online: 28 JUN 2008
© 2008 The Authors. Journal compilation © 2008 Anatomical Society of Great Britain and Ireland
Journal of Anatomy
Volume 213, Issue 3, pages 296–307, September 2008
How to Cite
Manzano, A. S., Abdala, V. and Herrel, A. (2008), Morphology and function of the forelimb in arboreal frogs: specializations for grasping ability?. Journal of Anatomy, 213: 296–307. doi: 10.1111/j.1469-7580.2008.00929.x
- Issue published online: 25 AUG 2008
- Article first published online: 28 JUN 2008
- Accepted for publication 29 April 2008Article published online 19 June 2008
- arboreal frogs;
- muscle morphology
Frogs are characterized by a unique morphology associated with their saltatory lifestyle. Although variation in the form and function of the pelvic girdle and associated appendicular system related to specialized locomotor modes such as swimming or burrowing has been documented, the forelimbs have typically been viewed as relatively unspecialized. Yet, previous authors have noted versatility in forelimb function among arboreal frogs associated with feeding. Here we study the morphology and function of the forelimb and hand during locomotion in two species of arboreal frogs (Litoria caerulea and Phyllomedusa bicolor). Our data show a complex arrangement of the distal forelimb and hand musculature with some notable differences between species. Analyses of high-speed video and video fluoroscopy recordings show that forelimbs are used in alternating fashion in a diagonal sequence footfall pattern and that the position of the hand is adjusted when walking on substrates of different diameters. Electromyographic recordings show that the flexors of the hand are active during substrate contact, suggesting the use of gripping to generate a stabilizing torque. Measurements of grasping forces in vivo and during stimulation experiments show that both species, are capable of executing a so-called power grip but also indicates marked differences between species, in the magnitude of forces generated. Stimulation experiments showed an increased control of digit flexion in the more specialized of the two species, allowing it to execute a precision grip paralleled only by that seen in primates.