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 A cell senses its own curves: New research from the MBL Whitman Center
29.04.2016 | Marine Biological Laboratory

nachricht A New Discovery in the Fight against Cancer: Tumor Cells Switch to a Different Mode
29.04.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Winzige Mikroroboter, die Wasser reinigen können

Forscher des Max-Planck-Institutes Stuttgart haben winzige „Mikroroboter“ mit Eigenantrieb entwickelt, die Blei aus kontaminiertem Wasser entfernen oder organische Verschmutzungen abbauen können.

In Zusammenarbeit mit Kollegen in Barcelona und Singapur verwendete die Gruppe von Samuel Sánchez Graphenoxid zur Herstellung ihrer Motoren im Mikromaßstab. D

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: Bewegungen in der lebenden Zelle beobachten

Prinzipien der statistischen Thermodynamik: Forscher entwickeln neue Untersuchungsmethode

Ein Forscherteam aus Deutschland, den Niederlanden und den USA hat eine neue Methode entwickelt, mit der sich Bewegungsprozesse in lebenden Zellen nach ihrem...

Im Focus: Faszinierender Blick in den Zellkern

Veröffentlichungen in Nature Communications zur DNA-Replikation

Vor jeder Zellteilung muss die Erbsubstanz kopiert werden. Die Startpunkte der DNA-Verdoppelung in Zellen von Menschen und Mäusen haben Wissenschaftler um...

Im Focus: Dauerbetrieb der Tokamaks rückt näher

Aussichtsreiche Experimente in ASDEX Upgrade / Bedingungen für ITER und DEMO nahezu erfüllt

Die ihrer Natur nach in Pulsen arbeitenden Fusionsanlagen vom Typ Tokamak sind auf dem Weg zum Dauerbetrieb. Alexander Bock, Wissenschaftler im...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

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

VDE|DGBMT veranstaltet Tagung zur patientennahen mobilen Diagnostik POCT

28.04.2016 | Veranstaltungen

Norddeutsche Herztage: 300 Experten treffen sich in Kiel

28.04.2016 | Veranstaltungen

Landwirtschaft und Lebensmittel - Analytische Chemiker: Wächter über Umwelt und Gesundheit

28.04.2016 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

SmartF-IT passt Produktionsprozesse flexibel an

29.04.2016 | Informationstechnologie

Neue Entdeckung im Kampf gegen Krebs: Tumorzellen stellen Betrieb um

29.04.2016 | Biowissenschaften Chemie

Fettreiche Ernährung lässt Gehirn hungern

29.04.2016 | Biowissenschaften Chemie