Notices |
Hello!
Either you have not registered on this site yet, or you are registered but have not logged in. In either case, you will not be able to use the full functionality of this site until you have registered, and then logged in after your registration has been approved.
Registration is FREE, so please register so you can participate instead of remaining a lurker....
Please note that the information requested during registration will be used to determine your legitimacy as a participant of this site. As such, any information you provide that is determined to be false, inaccurate, misleading, or highly suspicious will result in your registration being rejected. This is designed to try to discourage as much as possible those spammers and scammers that tend to plague sites of this nature, to the detriment of all the legitimate members trying to enjoy the features this site provides for them.
Of particular importance is the REQUIREMENT that you provide your REAL full name upon registering. Sorry, but this is not like other sites where anonymity is more the rule.
Also your TRUE location is important. If the location you enter in your profile field does not match the location of your registration IP address, then your registration will be rejected. As such, I strongly urge registrants to avoid using a VPN service to register, as they are often used by spammers and scammers, and as such will be blocked when discovered when auditing new registrations.
Sorry about all these hoops to jump through, but I am quite serious about blocking spammers and scammers at the gate on this site and am doing the very best that I can to that effect. Trust me, I would rather be doing more interesting things with my time, and wouldn't be making this effort if I didn't think it was worthwhile.
|
Herps In The News Local or national articles where reptiles or amphibians have made it into the news media. Please cite sources. |
11-13-2012, 06:04 AM
|
#1
|
|
Croc Jaws More Sensitive Than Human Fingertips
Quote:
Shannon Fischer
for National Geographic News
Published November 8, 2012
They may be lethal, leathery, and literally armored to the teeth, but crocodiles and alligators, it turns out, are sensitive types. Their snouts, in fact, are even more touch-sensitive than human fingertips, a new study says.
Part of the crocodilian reptile order, alligators have some 4,000 of tiny, raised black spots, or domes, on their heads, particularly along their jaws, inside their mouths, and between their teeth. Crocodiles have a similar setup, plus a liberal sprinkling over the rest of their bodies, bringing their total to about 9,000.
Scientists have known about these bumps—called integumentary sensory organs, or ISOs—for more than a century. But for a long time their purpose was a mystery.
Perhaps, some biologists suggested, the domes have a waterproofing purpose. Or maybe they detect faint electrical fields given off by prey—or salt, to alert crocs to unsafe drinking water.
In 2002 an alligator study seemed to crack the mystery. Croc dots, it revealed, could detect ripples from even a single drop of water-and therefore even very weak prey movements. (See "Rare Pictures: Crocodile Attacks Elephant.")
Until now, though, a couple of big questions continued to intrigue scientists: How did the domes work—and just how sensitive are they?
Feeling the Unfeelable
Vanderbilt University student Duncan Leitch took it upon himself to solve the mysteries. The results of his croc research appear today in a Journal of Experimental Biology report coauthored with his advisor, biologist Ken Catania.
After taking a croc-handling course (pro tip: poke an unruly croc on the nose—especially sensitive due to those dots), Leitch ordered relatively small alligators from refuges and crocodiles from commercial breeders.
Examining domes on 18 American alligators and 4 Nile crocodiles, he found that the spots contained touch receptors tuned specifically to pressure and vibration, plus a host of raw nerve endings. (Related: "Crocodiles Have Strongest Bite Ever Measured, Hands-on Tests Show.")
The domes didn't respond to salt or electricity, but they did respond to the touch of von Frey filaments—hairlike, standardized wires used to gauge sensation levels. In fact, some of the domes turned out to be so sensitive they could detect pressures too small to measure via the filaments.
"My professor and I didn't believe at first that they could be that reactive," Leitch said. "We closed our eyes and tried to tickle each other with [the filaments] on our fingertips, and neither of us could even feel it."
Later, using croc carcasses, the researchers stained the dome nerves with dye and traced them back to the brain. They turned out to be tied into a system stemming from the trigeminal nerve—associated with biting, chewing, and swallowing. Go figure.
Why So Touchy?
The new croc-sensitivity study "is really valuable," said Kent Vliet, co-chair of the Association of Zoos & Aquariums' Crocodilian Advisory Group.
"This was exactly what I had hoped somebody would do with ISOs, in terms of really looking at the distribution and the electrophysiology, because that's really the way to answer these questions about function in a tiny sense organ like this."
But why would alligators and crocodiles need such supersensitive skin? Leitch has his suspicions.
He's certain the animals use their mouths to feel for and snap up food (he videotaped crocodiles doing exactly that).
And mother crocodilians also use their mouths to help their young out of their shells and to hold the offspring between their jaws for protection. "That definitely would require a great deal of sensitivity," he said.
(Also see "Robot Revolution: New Material Sensitive as Human Skin.")
Future studies, Leitch hopes, will map out how the bumps' sensations are represented in the reptiles' brains—and perhaps uncover why crocodiles have bumps on their whole bodies, whereas on alligators, only the snouts have domes.
And, given his apparently undiminished enthusiasm, he may be just the guy to find out.
"What's interesting to me is that such a scaly animal, one that's so heavily armored, could have a sensitivity that rivals or surpasses our tactile abilities," Leitch said. "But they have all these little tactile areas that are so exquisitely sensitive—it seems really amazing."
|
http://news.nationalgeographic.com/n...nsitive-touch/
|
|
|
Join
now to reply to this thread or open new ones
for your questions & comments! FaunaClassifieds.com
is the largest online community about Reptile
& Amphibians, Snakes, Lizards and number one
classifieds service with thousands of ads to look
for. Registration is open to everyone and FREE.
Click Here to Register!
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -4. The time now is 04:45 AM.
|
|