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Press release No. 19/2016, 2016-01-26 | zur deutschen Fassung | RSS | print version | Search

The frog as an acrobat


We are aware of over 6,600 species of frog worldwide. Most of them are amazing jumpers. Around a quarter of all frog species live in trees and bushes. Until now, it was largely unknown as to how these tree-dwelling frogs managed to jump to and land safely on thin branches and twigs. A student, together with scientists from Kiel University, has now been able to document for the first time, how these creatures perform genuine feats in order to jump and land on thin twigs. Their research findings are reported in the current edition (January 23) of the "Journal of Comparative Physiology A".

"When they jump, they stretch out all four legs, a front or back leg sticks to the twig and they swing round like an acrobat swings round a bar. The other alternative is a belly flop", says Nienke Bijma, Biology student and main author, to describe the landing techniques of the South American Amazon milk frog (Trachycephalus resinifictrix). For her Bachelor's thesis, she used a high-speed video camera to film the animals landing onto a thin stick, then evaluated the recordings. "We discovered that the frogs travelled through the air at an average speed on 1.34 metres per second. When they land, the sticky pads on the tips of the frogs' toes hold up to 14 times their body weight", added co-author Dr Thomas Kleinteich, who was also involved in the study within the Functional Morphology and Biomechanics (chair: Professor Stanislav Gorb).

The team placed particular emphasis on documenting movement procedures that were as natural as possible. Previous work on this topic was only concerned with how ground-dwelling frogs landed on flat surfaces. The acrobatic feats of tree-dwelling species remained undiscovered, according to Bijma and Kleinteich. In the experiment in Kiel, the frogs had to make it to a bar measuring one centimetre in diameter, from a distance of 25 centimetres - which is still around four times their body length. Child's play for these animals, as Kleinteich knows: "It doesn't seem to matter which of the frog's extremities sticks to the twig first. Once it has made contact with the twig, even one sticky pad on the frog's toes is strong enough to hold the animal securely." Further research will show the extent to which the creatures are able to actively control their landing.

Author/Copyright: Functional Morphology and Biomechanics

Original publication:
“Landing on branches in the frog Trachycephalus resinifictrix (Anura: Hylidae)”. Nienke N. Bijma, Stanislav N. Gorb, and Thomas Kleinteich. Journal of Comparative Physiology A 2016. http://link.springer.com/article/10.1007/s00359-016-1069-0

Photos/material is available for download:
Please pay attention to our ► Hinweise zur Verwendung

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The Amazon milk frog lives in trees in the South American rainforest.
Photo/Copyright: Functional Morphology and Biomechanics

Image to download:
www.uni-kiel.de/download/pm/2016/2016-019-1.jpg

Click to enlarge

Close-up image of the frog's toes. The tips of the toes have sticky, disc-like pads.
Photo/Copyright: Functional Morphology and Biomechanics

Image to download:
www.uni-kiel.de/download/pm/2016/2016-019-2.jpg

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Drawing of the various landing techniques: (A) landing on the stomach; (B) front leg sticks, swing over a twig; (C) front leg sticks, swing under a twig; (D) back leg sticks
Credit/Copyright: Nienke Bijma

Image to download:
www.uni-kiel.de/download/pm/2016/2016-019-3.jpg

Click to enlarge

The Amazon milk frog in motion.
Photo/Copyright: Functional Morphology and Biomechanics

Image to download:
www.uni-kiel.de/download/pm/2016/2016-019-4.jpg


Contact:
Dr Thomas Kleinteich
Functional Morphology and Biomechanics, Kiel University
email: tkleinteich@zoologie.uni-kiel.de
phone: +49 (0)431 880 4509



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