Navigation Links
Tactile croc jaws more sensitive than human fingertips
Date:11/7/2012

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'.


'/>"/>

Contact: kathryn Knight
kathryn@biologists.com
44-078-763-44333
The Company of Biologists
Source:Eurekalert

Related biology news :

1. Ultrasensitive photon hunter
2. Sensitive test helps improve vaccine safety
3. Medbox Developing a Patent Pending Wall-Mounted Biometric Kiosk for Storage of Sensitive Medicine Samples and Supplies for Doctors Offices.
4. Ultrasensitive biosensor promising for medical diagnostics
5. Culturally sensitive research in United Arab Emirates pinpoints indoor air quality risks
6. Obese dogs at risk of health condition experienced by humans
7. National Heart Centre Singapore develops worlds first human heart cell model
8. A whale with a distinctly human-like voice
9. Pigs look healthy but test positive for flu at fairs; transmission seen between pigs and humans
10. Humans were already recycling 13,000 years ago
11. Relieving plant stress could eventually help humans relax
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/20/2016)... and GENEVA, Dec, 20, 2016   Valencell ... sensor technology, and STMicroelectronics (NYSE: STM), a ... of electronics applications, announced today the launch of ... for biometric wearables that includes ST,s compact ... Valencell,s Benchmark™ biometric sensor system. Together, SensorTile ...
(Date:12/16/2016)... -- The global wearable medical device market, in terms of value, ... 5.31 billion in 2016, at a CAGR of 18.0% during the ... ... medical devices, launch of a growing number of smartphone-based healthcare apps ... providers, and increasing focus on physical fitness. Furthermore, ...
(Date:12/15/2016)... Advancements in biometrics will radically ... wellbeing (HWW), and security of vehicles by ... vehicles begin to feature fingerprint recognition, iris ... monitoring, brain wave monitoring, stress detection, fatigue ... detection. These will be driven by built-in, ...
Breaking Biology News(10 mins):
(Date:1/21/2017)...   Boston Biomedical , an industry leader in ... stemness pathways, today presented data from two clinical studies ... American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium ... In a Phase Ib/II study of napabucasin – ... stemness pathways by targeting STAT3 – colorectal cancer (CRC) ...
(Date:1/20/2017)... 20, 2017 Stock-Callers.com explores the ... influenced the most recent performances of select equities. In ... RGLS ), Abeona Therapeutics Inc. (NASDAQ: ... ), and Sage Therapeutics Inc. (NASDAQ: SAGE ... View Research, global Biotech market size is expected to reach $604.40 billion by ...
(Date:1/20/2017)... NEW YORK , January 20, 2017 ... Health Organization, cancer is one of leading causes of ... in 2012. Although the number of cancer related deaths ... since 1990. Rising in incidence rate of various cancers ... According to a research report by Global Market Insights, ...
(Date:1/19/2017)... , Jan 19, 2017 Research and ... by Profiling Technology, Biomolecules, Cancer Type, Application - Global Opportunity Analysis ... ... forecasts that the global market is projected to reach $15,737 million ... 13% from 2016 to 2022. Omic technologies segment ...
Breaking Biology Technology: