An Amazing Sense: Touch at a Distance!

Many say that the legend of the mermaids, half woman, half fish, was triggered by sailors that saw from a distance and for the first time the manatees or sea cows.

But if diving in manatees' water you see one of these huge "mermaids" approaching to give you what it looks like a kiss, do not panic!

Researchers have recently found a unique sense of touch in these animals: they can "touch at a distance"-an ability to "feel" objects and events in the water from relatively far away.

Biologists at the University of Florida in Gainesville had discovered that the manatees' brain area dedicated to touching is "especially large", even larger than in animals known to be particularly sensitive feelers, like star-nosed moles. Recently, the same team discovered that these marine relatives of the elephants are covered with special sensory hairs all over their body. "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 Roger Reep, from the university's College of Veterinary Medicine.

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

"As for a manatee puckering up for a diver, that's just the animal's way of collecting information by spreading out the hairs around its mouth to sense what it's approaching." explained biologist Diana Sarko. "Those facial hairs are actively exploring the environment around them," she said.

This bizarre sense explains how manatees are able to make long and convoluted migrations in murky waters, where vision is of no use (in fact, they have poor eyesight). "One example is the impressive journey made by manatees in a mazelike network of waterways called Ten Thousand Islands near Naples, Florida", said Reep.

"When you go out there for the first time in a boat and you don't know the area, you get lost in about two minutes," Reep said.

But sea cows make daily journeys through the watery labyrinth, leaving the rivers each morning to forage in the large beds of sea grass offshore before swimming back at night. "And so the question is, how do they know where they're going?" Reep said.

"We're talking about relatively dark water, and we already know manatees don't have very good visual acuity anyway."

"So one of the possibilities here is that they're able to use their tactile hairs that are all over their bodies to detect the movement of water and tell them where they are in the environment, and that they're using [their sensory hairs] as a navigational tool."

"When a hurricane is coming, they get out of the area, so you do have to wonder what kind of sense they have and what they're able to detect," said Sarko. "But we wish we knew so much more about their capabilities when it comes to using these hairs."

Researchers at Mote Marine Laboratory in Sarasota are assessing with two captive manatees how these animals explore the environment with their specialized hairs. "By doing studies like that, you start to build up some real insight into what kind of intelligence [the manatees] are constructing with this information," Reep said.

With such a sensory ability, the researchers are puzzled why manatees cannot detect their greatest danger, the boats, which killed by collision 86 manatees in Florida in 2006, the second highest toll ever recorded for such deaths. Biologists believe this danger is so new for the animals, that they did not have the time to adapt. "It is such an evolutionarily novel phenomenon that I think they haven't been able to adapt to it yet", said Sarko. "But as research reveals more about manatees' abilities, science may help conservation efforts evolve to better protect the animals," she said.

"Our overriding goal is to be able to understand [manatees] a little bit better and to understand how they perceive their environment," Sarko said.

"By doing that, since they haven't been able to adapt that well to us, maybe we can adapt to them a little bit better."

Photo credit: Blake de Pastino/NGS