Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Tactile croc jaws more sensitive than human fingertips

08.11.2012
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 http://jeb.biologists.org.

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'.

IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org/content/215/23/4217.abstract

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 jeb.biologists.com 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 permissions@biologists.com

kathryn Knight | EurekAlert!
Further information:
http://www.biologists.com

More articles from Life Sciences:

nachricht Nesting aids make agricultural fields attractive for bees
20.07.2017 | Julius-Maximilians-Universität Würzburg

nachricht The Kitchen Sponge – Breeding Ground for Germs
20.07.2017 | Hochschule Furtwangen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Molekulares Lego

Sie können ihre Farbe wechseln, ihren Spin verändern oder von fest zu flüssig wechseln: Eine bestimmte Klasse von Polymeren besitzt faszinierende Eigenschaften. Wie sie das schaffen, haben Forscher der Uni Würzburg untersucht.

Bei dieser Arbeit handele es sich um ein „Hot Paper“, das interessante und wichtige Aspekte einer neuen Polymerklasse behandelt, die aufgrund ihrer Vielfalt an...

Im Focus: Das Universum in einem Kristall

Dresdener Forscher haben in Zusammenarbeit mit einem internationalen Forscherteam einen unerwarteten experimentellen Zugang zu einem Problem der Allgemeinen Realitätstheorie gefunden. Im Fachmagazin Nature berichten sie, dass es ihnen in neuartigen Materialien und mit Hilfe von thermoelektrischen Messungen gelungen ist, die Schwerkraft-Quantenanomalie nachzuweisen. Erstmals konnten so Quantenanomalien in simulierten Schwerfeldern an einem realen Kristall untersucht werden.

In der Physik spielen Messgrößen wie Energie, Impuls oder elektrische Ladung, welche ihre Erscheinungsform zwar ändern können, aber niemals verloren gehen oder...

Im Focus: Manipulation des Elektronenspins ohne Informationsverlust

Physiker haben eine neue Technik entwickelt, um auf einem Chip den Elektronenspin mit elektrischen Spannungen zu steuern. Mit der neu entwickelten Methode kann der Zerfall des Spins unterdrückt, die enthaltene Information erhalten und über vergleichsweise grosse Distanzen übermittelt werden. Das zeigt ein Team des Departement Physik der Universität Basel und des Swiss Nanoscience Instituts in einer Veröffentlichung in Physical Review X.

Seit einigen Jahren wird weltweit untersucht, wie sich der Spin des Elektrons zur Speicherung und Übertragung von Information nutzen lässt. Der Spin jedes...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: Das Proton präzise gewogen

Wie schwer ist ein Proton? Auf dem Weg zur möglichst exakten Kenntnis dieser fundamentalen Konstanten ist jetzt Wissenschaftlern aus Deutschland und Japan ein wichtiger Schritt gelungen. Mit Präzisionsmessungen an einem einzelnen Proton konnten sie nicht nur die Genauigkeit um einen Faktor drei verbessern, sondern auch den bisherigen Wert korrigieren.

Die Masse eines einzelnen Protons noch genauer zu bestimmen – das machen die Physiker um Klaus Blaum und Sven Sturm vom Max-Planck-Institut für Kernphysik in...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Operatortheorie im Fokus

20.07.2017 | Veranstaltungen

Technologietag der Fraunhofer-Allianz Big Data: Know-how für die Industrie 4.0

18.07.2017 | Veranstaltungen

DFG unterstützt Kongresse und Tagungen - September 2017

17.07.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

1,4 Millionen Euro für Forschungsprojekte im Industrie 4.0-Kontext

20.07.2017 | Förderungen Preise

Von photonischen Nanoantennen zu besseren Spielekonsolen

20.07.2017 | Physik Astronomie

Bildgebung von entstehendem Narbengewebe

20.07.2017 | Biowissenschaften Chemie