Evolution Research - General Evolution News

New research suggests that manatees' tactile sense is so finely tuned that the animals may experience 'touch at a distance' - an ability to 'feel' objects and events in the water from relatively far away.

In recent studies marine biologists Roger Reep and Diana Sarko at the University of Florida in Gainesville found that the giant mammals are covered with special whiskerlike hairs that act as sensors.

'We discovered that [manatees] have what are called tactile hairs all over their bodies, unlike most mammals, which just have whiskers on their faces,' said Reep, from the university's College of Veterinary Medicine.

Together these tactile hairs form a kind of sensory array, the biologists say, possibly allowing manatees to detect changes in current, water temperature, and even tidal forces.

...In a separate study (*see below) Reep and Sarko also found that manatees have more brain space dedicated to the sense of touch than other mammals do.

The research, published last month in the journal Brain, Behavior and Evolution, found that brain regions associated with touch are "especially large" in manatees - as large as or larger than in animals known to be particularly sensitive feelers, like star-nosed moles (**see below).

"That just reinforced our idea that [manatees] really are relying on their sense of touch to be able to navigate their world," Sarko said.

Full National Geographic article at "Manatees Have "Long-Distance" Sense of Touch, Experts Say"

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*"Somatosensory Areas of Manatee Cerebral Cortex: Histochemical Characterization and Functional Implications"

Abstract

A histochemical and cytoarchitectural analysis was completed for the neocortex of the Florida manatee in order to localize primary sensory areas and particularly primary somatosensory cortex (SI). Based on the location of cytochrome oxidase-dense staining in flattened cortex preparations, preliminary functional divisions were assigned for SI with the face represented laterally followed by the flipper, body and tail representations proceeding medially. The neonate exhibited four distinct patches in the frontoparietal cortex (presumptive SI), whereas juvenile and adult specimens demonstrated a distinct pattern in which cytochrome oxidase-dense staining appeared to be blended into one large patch extending dorsomedially. This differential staining between younger versus older more developed animals was also seen on coronal sections stained for cytochrome oxidase, myelin, or Nissl bodies. These were systematically analyzed in order to accurately localize the laminar and cytoarchitectural extent of cytochrome oxidase staining. Overall, SI appears to span seven cytoarchitectural areas to which we have assigned presumptive functional representations based on the relative locations of cytochrome oxidase-dense staining.

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**Star-nosed mole - see the second part of New Research Shows Larval Fish Use Smell to Return to Coral Reefs (Video): "Moles, Shrews Can Smell Prey While Underwater"

A post on Manatees from Tuesday, August 29, 2006: "Manatee Bones Lead Stanford Scientist to New Insight on Evolution"

Technorati: new, research, manatees, tactile, sense, feel, mammals, sensors, hairs, sensory, array, current, water, temperature, study, brain, touch, behavior, evolution, star, nosed, moles, national geographic, cerebral, cortex, flipper, body, tail, manatee, mole, insight

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