Excerpts from Jim Conrad's
Naturalist Newsletter

from the October 9, 2011 Newsletter issued from written at Mayan Beach Garden Inn 20 kms north of Mahahual, Quintana Roo, México
A MUD-TURTLE'S BARBELS

I don't pick up turtles, not wanting to upset them, but this week I was with some visitors who just had to see one at eye level, so they picked up a Red-cheeked Mud Turtle, KINOSTERNON SCORPIOIDES,  found crossing a road during a nature tour. You can see a nice close-up of the face below:

Red-cheeked Mud Turtle, KINOSTERNON SCORPIOIDES, face with barbels below

That picture very nicely shows four tiny, fingerlike, fleshy projections dangling from the turtle's throat area. Those are "barbels," which occur on many species of fish and turtles. A catfish's whiskers are barbels. When identifying fish and turtles, often the number and placement of barbels serve as good field marks.

You can imagine that barbels provide some kind of touch guidance as the turtle forages atop the mud in dark, muddy water, but it seems that they're capable of much more than that. Turtle barbels contain olfactory nerve endings, which means that the barbles are used for smelling. Turtles on dry land can smell odors as we do, but in water turtles with such barbels have this extra odor-sensing method. As the turtle scoots its chin atop submerged mud, through its barbels it's smelling what passes below it.