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 Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Die Quanten-Schnüffelnase

Der Laser, der zugleich ein Detektor ist: An der TU Wien wurde ein mikroskopisch kleiner Sensor entwickelt, mit dem man gleichzeitig verschiedene Gase nachweisen kann.

Wir Menschen erschnüffeln unterschiedliche Gerüche und Düfte durch chemische Rezeptoren in unserer Nase. Doch für den technischen Nachweis von Gasen greift man...

Im Focus: „Molekül-Selfie“ enthüllt den Aufbruch einer chemischen Bindung

Wissenschaftlern des Institute of Photonic Sciences (Barcelona) ist es gelungen, die Position aller Atome eines Moleküls zu verfolgen während der Aufbruch einer der chemischen Bindungen ein einzelnes Proton freisetzt. Hierzu wurde ein am Heidelberger Max-Planck-Institut für Kernphysik entwickeltes Reaktionsmikroskop verwendet [Science, 21. Oktober 2016].

Man stelle sich vor, die einzelnen Atome eines Moleküls ließen sich während einer chemischen Reaktion beobachten: Wie sie sich umlagern, um eine neue Substanz...

Im Focus: Elektronik mit Licht beschleunigen

Wissenschaftler am MPQ haben mit ultrakurzen Laserpulsen die schnellsten jemals erzeugten elektrischen Ströme in Festkörpern gemessen. Die Elektronen führten in einer Sekunde achtmillionen Milliarden Schwingungen aus, ein absoluter Rekord für die Steuerung von Elektronen in Festkörpern.

Die Leistungsfähigkeit von modernen elektronischen Geräten wie Computern oder Mobilfunkgeräten wird durch die Geschwindigkeit bestimmt, mit der die...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Innovative Lösungen für multifunktionale Werkstoffe und effiziente kurze Prozessketten

IPF Dresden präsentiert sich im Science Campus der Kunststoffmesse 2016

Auf der weltgrößten Kunststoffmesse K 2016 vom 19. bis 26. Oktober 2016 in Düsseldorf präsentiert sich das Leibniz-Institut für Polymerforschung Dresden e. V....

Alle Focus-News des Innovations-reports >>>



im innovations-report
in Kooperation mit academics

Experten treffen sich am 27. Oktober zum siebten „NORTH Regio Day on Infection“ in Braunschweig

20.10.2016 | Veranstaltungen

Sicherheit und Vertrauen in der vernetzten Welt

20.10.2016 | Veranstaltungen

Fachtagung „55. Heidelberger Grand Round“ mit internationalen Krebsexperten

20.10.2016 | Veranstaltungen

Weitere VideoLinks >>>
Aktuelle Beiträge

Die Quanten-Schnüffelnase

21.10.2016 | Energie und Elektrotechnik

Sterilkonnektoren der nächsten Generation

21.10.2016 | Biowissenschaften Chemie

Neuer Mechanismus hinter der Wirkung von Hautkrebs-Medikament Imiquimod entschlüsselt

21.10.2016 | Biowissenschaften Chemie