Manatees

From the NYT, courtesy of Reid: manatees may have smooth brains, but that doesn't mean they have dull senses. It is a long article and you should read it all, but here is an example.

"In research over the last five years, Dr. Reep and his colleagues have shown that manatees have 2,000 facial vibrissae of varying thickness, 600 of them in the so-called oral disk, a circular region between mouth and nose that the manatee uses much like an elephant’s trunk, to grasp or explore objects. Each facial vibrissa is linked with 50 to 200 nerve fibers. An additional 3,000 vibrissae are spaced less densely over the rest of the body.

(Snip)

"In testing, Buffett, Hugh and other captive animals have proved just how acute a manatee’s tactile sense can be. Using the bristles on the oral disk and the upper lips, manatees can detect minute differences in the width of grooves and ridges on an underwater panel. A manatee tested by a team of researchers in Germany could distinguish differences as small as 0.05 millimeters, as well as an elephant performing the same task with its trunk, and almost as well as a human. Hugh and Buffett did even better, outperforming the elephant and, in Buffett’s case, the human.

(Snip)

"A sensory modality that is so important should be prominently represented in the brain. And, confirming an observation first made by a German scientist in 1912, Dr. Reep’s research team has identified large clusters of cells called Rindenkerne in sensory processing areas in the deep layers of the manatee’s cerebral cortex. These clusters, the researchers suspect, are the manatee equivalents of the cell groupings called barrels found in other whiskered species like mice and rats, regions that process sensory information from the vibrissae.

"Even more tantalizing is that, in the manatee, these clusters extend into a region of the brain believed to be centrally involved with sound perception.

“Either these things have nothing to do with the hair at all, or the more exciting possibility is that perhaps somatic sensation is so important that the specialized structure is overlapping with processing going on in auditory areas,” Dr. Reep said."

Read it all.