Frog tongue acts as muscle-powered adhesive tape

Abstract

Frogs are well known to capture fast-moving prey by flicking their sticky tongues out of the mouth. This tongue projection behaviour happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2000 frames per second through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure-sensitive adhesives, and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nanoscale fibres underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, to the best of our knowledge, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues.

Diffusible iodine‐based contrast‐enhanced computed tomography (diceCT): an emerging tool for rapid, high‐resolution, 3‐D imaging of metazoan soft tissues

“…(); [22] Kleinteich et al. (); [23] Kleinteich & Gorb (); [24] Kleinteich & Gorb (); [25] Lautenschlager et al. (); [26] Metscher, ; [27] Metscher (); [28] Pauwels et al.…”

“…), and in a wide variety of post‐embryonic bony fishes (Metscher, ; Kleinteich et al. ), amphibians (Kleinteich & Gorb, ,b), reptiles (Tsai & Holliday, ; George & Holliday, ; Holliday et al. ; Gignac & Kley, ; Tsai & Holliday, ), birds (Düring et al.…”

Hunting with sticky tape: functional shift in silk glands of araneophagous ground spiders (Gnaphosidae)

“…The bottom of the container was removed and replaced by a clear glass slide, which was set in a custom-built 3D-printed frame containing lateral tunnels, in which the lenses of a gooseneck lamp were inserted. This induced frustrated reflection in all strands of silks contacting the glass surface (see Kleinteich and Gorb, 2015, for details). Additional lighting was applied from below the glass slide.…”

Peer Review #1 of "Digital dissection of the pelvis and hindlimb of the red-legged running frog, Phlyctimantis maculatus, using Diffusible Iodine Contrast Enhanced computed microtomography (DICE μCT) (v0.1)"

“…We will use both traditional and emerging 3D techniques to study the musculoskeletal anatomy of this 'multifunctional' frog in detail. Using aqueous iodine to increase the radiopacity of the soft tissues, diffusible iodine contrast enhanced computed microtomography (DICE μCT) allows anatomical analyses to be conducted non-destructively (Metscher, 2009a;2009b;Herdina et al, 2010;Vickerton et al, 2013;Gignac & Kley, 2014;Lautenschlager et al, 2014;Herdina et al, 2015;See Gignac et al, 2016 for a full review) and has emerged as a powerful functional morphology tool to visualise intricate musculoskeletal anatomy across diverse systems (For example: Jeffery et al, 2011;Baverstock et al, 2013;Düring et al, 2013;Cox & Faulkes, 2014;Lautenschlager et al, 2014;Holliday et al, 2013;Gignac & Kley, 2014;Kleinteich & Gorb, 2015;Klinkhamer et al, 2017, Bribiesca-Contreras & Sellers, 2017, for a comprehensive review).…”