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40940.  Tue Dec 20, 2005 4:16 pm Reply with quote

Why do narwhals have tusks?

Narwhals swim in icy Arctic waters and eat fish, squid, and shrimp. They grow to about 15 feet long and 3,500 pounds, and grow a spiraled but straight tusk, often more than half as long as their body length, out of their upper jaws and through their lips. Tusked narwhals are mainly male, though a few females grow them too.

Until recently, the function of the tusk has been a mystery, but now a dentist named Dr Martin Nweeia has used an electron microscope to examine it, and believes it to be a sensory organ. Unlike human teeth, the pathways to the sensitive nerves are not covered with enamel. Tiny tubules expose ten million nerve endings to the air and water. He believes that the narwhal uses its tusk to monitor temperature, pressure and salinity changes in its environment. This may help it avoid getting trapped in pack ice.

Narwhals often gently rub their tusks together, and Dr Nweeia says that given all the exposed nerve endings, the whales probably experience a "unique sensation."

43742.  Fri Jan 06, 2006 11:50 pm Reply with quote

Remember the Narwhals, don't dump your aluminium foil in the sea - OUCH!

43750.  Sat Jan 07, 2006 5:16 am Reply with quote

However, the matter is far from settled at it remains a highly contentious issue.

But if the tusk is so important for survival, how come female narwhals and a minority of male narwhals get by without them, asks marine biologist Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources in Nuuk. "Females and males often travel in separate groups far apart, and females are apparently doing just fine without the sensory advantages that Dr Nweeia claims the males have." He believes the purpose of the tusk is to establish hierarchy and dominance.

From issue 2531 of New Scientist magazine, 24 December 2005, page 6

43831.  Sat Jan 07, 2006 10:51 am Reply with quote

It may well be a way of establishing hierarchy and dominance, but maybe it also gives the tusked male narwhal a survival advantage, if it has the sensory properties Dr Nweeia claims? If so, then the percentage of male narwhals with tusks ought to be increasing. However, it could have a counter-evolutionary effect if it makes the tusk-bearing narwhal more likely to be hunted, I suppose.

47264.  Mon Jan 23, 2006 11:31 am Reply with quote

They've just auctioned a 1780s licensed Narwhal tusk with good provinance on Flog It!. £2,000 or so would appear to be the going rate.

Rory Gilmore
47273.  Mon Jan 23, 2006 11:47 am Reply with quote

Generally speaking, do the things used to establish heirarchy and dominance not actually have a use as well? Because, like, if a man was much stronger than me I may fear and obey him to an extent, but if he had a meaningless attachment to his body (a tattoo say) it wouldn't make a differance.

Last edited by Rory Gilmore on Mon Jan 23, 2006 11:53 am; edited 1 time in total

47274.  Mon Jan 23, 2006 11:52 am Reply with quote

What if he could stab you with his tattoo?

Rory Gilmore
47275.  Mon Jan 23, 2006 11:54 am Reply with quote

But he can't.

47391.  Tue Jan 24, 2006 7:15 am Reply with quote

Do large antlers on male deer have a practical use?

Or peacock tails?

47397.  Tue Jan 24, 2006 7:59 am Reply with quote

You mean you're not more afraid of someone if they have a tattoo on their arm? I am, and that's surely one of the points of them - to make someone look 'stronger' without them having to prove it. 'Decoration' is just a place-holder word for all the other things that are going on between wearer and the seer.

As well as showing seniority, antlers are very practical. They allow the wearer to match his body strength with that of another deer without either party being injured. They are enormously strong and springy, and the gap between them (where the skull is vulnerable) is always just less than the width of an antler, so the skull itself never gets hit.

As for peacock tails, they display an individual's strength - he still manages to 'make a living' even carrying around such an encumberance.

They have many purposes, some visual, some physical... Anything that gives the genes responsible a better chance of getting into the next generation will select for that characteristic.


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