Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 


Tactile croc jaws more sensitive than human fingertips

Armoured in elaborate scales, the skins of crocodiles and alligators are much prized by the fashion industry. But sadly, not all skins are from farmed animals.

Some are from endangered species and according to Ken Catania from Vanderbilt University, USA, sometimes the only way to distinguish legitimate hides from poached skins is to look at the distribution of thousands of microscopic pigmented bumps that pepper crocodiles' bodies.

Adding that the minute dome organs are restricted to the faces of alligators, Catania puzzled, 'What are the organs for?' Explaining that they have been proposed to detect subtle shifts in water salinity and shown to sense ripples in water, Catania says, 'We suspected that there might be more to the story', so he and Duncan Leitch teamed up to take a closer look at the small structures. The duo discovered that the bumps are tactile and even more touch sensitive than human fingertips. They publish their discovery in The Journal of Experimental Biology at

Observing the skin of American alligators and Nile crocodiles with scanning electron microscopy, Leitch could see that each dome was surrounded by a hinge depression. And when he sliced through a series of domes to identify the sensory receptor structures beneath, he found sensitive free nerve endings near the dome surface, and laminated corpuscle structures – which are vibration sensitive – and dermal Merkel complexes – which respond to sustained pressure – in the lowest skin layer.

Next, Leitch stained the nerve structures leading from the skin through the reptile's jaw and painstakingly traced the sensitive trigeminal nerve as it branched to the domes. 'The innervation of these jaws was incredible!' exclaims Catania. The entire jaw was infiltrated with a delicate network of nerves. 'There was a tremendous number of nerve endings and each of the nerve endings comes out of a hole in the skull', Leitch adds. Referring to the animal's combative lifestyle, he suggests that this arrangement protects the delicate trigeminal nerve fibres – carried inside the skull – from damage during attacks while maximising the nerve endings' sensitivity at the surface.

But none of these observations answered the question of which system the domes relay sensory information to. Recalling that the domes had been proposed to detect salinity changes and even electric fields, Leitch gently bathed the limbs of Nile crocodiles in brackish water while carefully recording the electrical activity in the spinal nerve, but couldn't detect a signal. And when he repeated the experiments while applying a weak electric field to the water, there was no response again. However, when Leitch gently touched one of the sensory domes with a minute hair designed to test human touch sensitivity, he discovered that the domes around the animals' teeth and jaws were even more touch sensitive than human finger-tips. And when he filmed crocodiles and alligators going about their business in the aquarium at night, he was impressed at how fast the animal's 50 ms response times were. 'As soon as they feel something touch, they snap at it', recalls Catania.

So, why do such well-armoured animals require such an exquisite sense of touch? Leitch suggests that this sensitivity allows the animals to distinguish rapidly between unpalatable pieces of debris and tasty prey while also allowing mother crocodiles to dextrously aid their hatching young by extracting them from the egg with their jaws. The pair is keen to understand how these sensory areas map onto the forebrain. Explaining that massive regions of the human brain are dedicated to processing touch sensory information, Catania says, 'Crocodilians are not an ancestor to humans, but they are an important branch that allows us to fill in key parts of the evolutionary puzzle for how sensory maps in the forebrain have evolved'.


REFERENCE: Leitch, D. B. and Catania, K. C. (2012). Structure, innervation and response properties of integumentary sensory organs in crocodilians. J. Exp. Biol. 215, 4217-4230.

This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT

kathryn Knight | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Understanding a missing link in how antidepressants work
25.11.2015 | Max Planck Institute of Psychiatry, München

nachricht Plant Defense as a Biotech Tool
25.11.2015 | Austrian Centre of Industrial Biotechnology (ACIB)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Follow Me: Forscher der Jacobs University steuern Unterwasser-Roboter erstmals durch Zeichensprache

Normalerweise werden Unterwasser-Roboter über lange Kabel von Booten oder von Land aus gesteuert. Forschern der Jacobs University in Bremen ist nun ein Durchbruch in der Mensch-Maschine-Kommunikation gelungen: Erstmals konnten sie einen Unterwasser-Roboter mit Hilfe von Gesten navigieren. Eine spezielle Kamera half dabei, die Zeichensprache in Befehle umzusetzen. Die Feldtests fanden im Rahmen des EU-geförderten Projektes CADDY „Cognitive Autonomous Diving buddy“ statt.

Archäologische Untersuchungen im Ozean und vergleichbare komplexe Forschungsprojekte unter Wasser sind auf die Unterstützung von Robotern angewiesen, um in...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser-Prozesssimulation erstmals auch als App verfügbar

Die Simulation von Prozessen bei der Lasermaterialbearbeitung ist in den letzten Jahren immer besser geworden. Die Software kann heute relativ gut voraussagen, was am Werkstück passiert. Leider ist sie hochkomplex und erfordert viel Rechenzeit. Durch eine clevere Vereinfachung können Experten vom Fraunhofer-Institut für Lasertechnik ILT erstmals eine Simulationssoftware anbieten, die Prozesse in Echtzeit rechnet und auch auf Tablets oder Smartphones läuft. Mit der schnellen Software lassen sich teure Versuche einsparen und noch besser optimale Prozessparameter finden.

Eine verlässliche Simulation von Laserprozessen war bislang eine Sache für Experten. Mit ausgefeilten Software-Paketen und viel Zeit auf Computerclustern...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantensimulation: Magnetismus besser verstehen

Heidelberger Physiker imitieren mit ultrakalten Atomen das Verhalten von Elektronen in einem Festkörper

Einen neuen Ansatz zur Erforschung des Phänomens Magnetismus haben Wissenschaftler der Universität Heidelberg entwickelt. Mithilfe von ultrakalten Atomen nahe...

Alle Focus-News des Innovations-reports >>>



im innovations-report
in Kooperation mit academics

Schlafmedizin-Jahrestagung: Beginnt die Schule zu früh? Steht Deutschland zu früh auf?

24.11.2015 | Veranstaltungen

Verantwortung der Internet-Giganten – Brauchen wir eine Politik und Ethik der Algorithmen?

24.11.2015 | Veranstaltungen

Computerphysik: Experten treffen sich an Universität Leipzig

23.11.2015 | Veranstaltungen

Weitere VideoLinks >>>
Aktuelle Beiträge

Neue Einsichten in die Funktionsweise von Antidepressiva

25.11.2015 | Biowissenschaften Chemie

Online-Landkarte der Plattform Industrie 4.0

25.11.2015 | Energie und Elektrotechnik

Pflanzenverteidigung als Biotech-Werkzeug

25.11.2015 | Biowissenschaften Chemie