http://54962754.qzone.qq.com Sat, 28 Nov 2009 16:48:07 GMT Qzone zh-cn Copyright (C), 2005-2008, Tencent Tech. Co., Ltd. Sat, 04 Jul 2009 11:58:57 GMT http://54962754.qzone.qq.com/blog/1246708737 http://news.bbc.co.uk/earth/hi/earth_news/newsid_8100000/8100876.stm

The secrets of ant sleep revealed
Matt Walker
Editor, Earth News

A fire ant worker: awake and alert.
Queen ants dozily dream, while workerants are forced to get by taking power naps, the first study of thesleeping habits of ants has revealed.
Queen fire ants fall into relatively long, deep sleeps and kip for an average of nine hours every day.
By contrast, workers sleep just half as much and get to rest by taking hundreds of short power naps.
This division of rest may help explain why queens live for years, while worker ants typically only live for months.
It also ensures that enough worker ants are awake at any one time to protect and serve the colony.
DebyCassill of the University of South Florida in St Petersburg, US teamedwith colleagues Skye Brown and Devon Swick of the same university, andGeorge Yanev of the University of Texas in Arlington, US to study thesleeping patterns of the fire ant Solenopsis invicta.
"I decided to see just how lazy the queens really were," says Cassill.
The large number and short naps by workers means that jobs in the nest never go unattended
Entomologist Deby Cassill
She and her colleagues raised a colony of fire ants in theirlaboratory, and created an artificial chamber containing three queens,30 workers and 30 large larvae. They placed a glass cover over the topof the chamber, allowing the ants to be continuously filmed from above.
Because fire ants generally live underground, the researchersexpected that their sleep patterns would not be determined by light anddark cycles. And that is what they found.
Workers fell asleepat irregular intervals, and not at the same time. But the sheer numberof incredibly short naps they took was striking.
On average, asingle worker ant would take 250 naps each day, with each one lastingjust over a minute. That equates to 4 hours and 48 minutes of sleep aday.
That also meant that 80 per cent of the workforce was awake and active at any one time.
"Thelarge number and short naps by workers means that jobs in the nestnever go unattended," says Cassill. "There is always a worker availablewhen the need arises. When work is slow, workers sleep more."
Equally striking was the contrast between the sleeping habits of the workers and of the queens they served.
Queen dreams
Thequeens fell asleep at far more regular intervals than their subjects.In fact, the queens even synchronised their naps, with all three queensdozing together.
"It's very cosy," says Cassill. "The synchronyof queens occurs because, like hound dogs, they pile atop each otherwhen they sleep. When awake, they separate."
On average, eachqueen would fall asleep 90 times a day, sleeping for just over 6minutes at a time. That equates to over nine hours of sleep each day.
Queens also slept in two distinct ways


This footage shows the queen ants sleeping while the worker ants scuttle around her, occasionally taking short naps.
Sometime they would just doze, with their antennae half raised andtheir mouths agape. When dozing, the queens could be easily roused byone another or by their workforce.
But often the queens would fall into much deeper sleep, with their antennae retracted and mouths closed.
Intriguingly,Cassill's team gathered evidence suggesting that the queen ants dreamwhen sleeping deeply. Frequently, the queens would quiver their foldedantennae when sleeping deeply.
This "rapid antennal movement(RAM) might be an analog to the rapid eye movement in vertebrates," theresearchers write in the Journal of Insect Behavior.
Disposable workers
The function of sleep is still unknown.
But for ants, the lack of rest for the workers seems to help ensure the queens get to live a peaceful existence.
"Workersare a disposable caste whose job is to buffer the queen and her royaloffspring from agents of death like exposure, starvation and predators.It is the workers who engage in the high risk behaviour, thus the queenlives a long life."
"Amazingly, queens can live six yearsbefore they die of old age. Whereas workers live six months to a yearand then die of old age or some accident during foraging," saysCassill.
The queens of other ant species can live even longer, reaching up to 45 years. ]]> http://54962754.qzone.qq.com/blog/1246708737#comment 134222337 Sat, 04 Jul 2009 11:58:57 GMT http://54962754.qzone.qq.com/blog/1246708737 http://54962754.qzone.qq.com/blog/1233817465 呵呵，舍我其谁。 ]]> http://54962754.qzone.qq.com/blog/1233817465#comment 134218240 Thu, 05 Feb 2009 07:04:25 GMT http://54962754.qzone.qq.com/blog/1233817465