Technoquest

Q) Do fish sweat? If not, how do they keep cool?

A) Fish do not sweat, unlike mammals, which live surrounded by air and cool themselves by evaporating moisture that they've sweated from their skin. Fish have no such means of maintaining a constant body temperature and their blood is usually at the same temperature as their surroundings. Although the temperature range tolerance of some fish (such as rock pool dwellers) is remarkable, most fish will die if the water becomes too hot, too cold, or changes temperature too suddenly. This is why care is needed when transferring fish into a new aquarium - so that they have sufficient time to adapt to the temperature of their new surroundings.

Q) Why don't electric eels electrocute themselves?

A) The reasons for electric eels' immunity to their shocks are not fully understood. Electric eels produce a current that runs from tail to head in the fish and in the opposite direction in the surrounding water. It is thought that they are protected from a short circuit by the insulating properties of their skin and the tissue surrounding the nerves. But it has been observed that if their skin is broken, the fish do show signs of distress from the effects of their own electric discharge.

Q) Why do you get a headache between your eyes at the top of your nose when you drink something cold?

A) All headaches are essentially caused by changes in blood flow in the head. As blood vessels open up and close they can trigger pain receptors. Headaches induced by eating something cold are officially called ice-cream headaches. When you eat something, cold blood rushes to the cold area to heat it up. To warm your mouth blood is diverted from the forehead and as the blood vessels there swell up, they trigger the pain receptors - giving a sharp pain at the top of the nose.

Q) Why are there only two sexes?

A) The presence of two sexes in a population is the most evolutionary stable of all systems. Three possible sexes would soon be reduced to two if a mutation occurred in one of them, allowing it to reproduce with only one of the others. The third sex would then die out. Quite why there are two sexes and not one is still a mystery, but in a changing environment two sexes are better at shuffling the gene pool to keep one step ahead of the latest disease.

Q) How much water does a tree drink?

A) Trees take in water at their roots and then lose it by evaporation through their leaves. A mature deciduous tree is thought to "drink" 50,000 litres of water in a year. On a warm windy day a tree can take up 2,000 litres of water - that's about 6,000 drink cans of fluid a day. It is estimated that 60 per cent of the water falling on a beech wood is returned to the atmosphere through the trees.

Q) Bird body temperatures are usually around 40 degrees centigrade - but they produce sperm at 35 degrees centigrade, so how do they keep their testes cooler than the body?

A) They don't! Birds only produce sperm at night when their body temperature drops by about 4-5 degrees centigrade. To stop it overheating the next day, they shunt the sperm into a kind of external lump called the cloacal projection - which outside the body is kept a little cooler at about 4- 5 degrees below body temperature.

Q) Why do we stretch?

A) There are several hypotheses about why we stretch. Firstly, when we are tired stretching uses muscles that draw the rib cage up and out - allowing the lungs to expand more fully - drawing in more oxygen. Stretching is also often accompanied by yawning, which is another strange phenomenon. No one knows the true reason for yawning - but it could also be to take more oxygen deep into the lungs. When we have just woken up, stretching may also be a way of warming the muscles ready for action by increasing the blood supply to them.

Q) If you can't get sunburnt through glass - by sitting in a car, for example - how can you get a tan from a sun-bed when the UV lights have glass around them?

A) Sun-beds have specially designed glass which doesn't have any iron impurities in it. Car windows deliberately have about 0.1 per cent iron metal in the glass to stop the plastic inside the cars from deteriorating. These metals reflect the UV light frequencies rather than transmitting them through the glass.

Questions and answers are provided by Science Line. You can use its Dial-a-scientist service on 0345 600444.

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA special investigation by Andy McSmith
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Design, Marketing and Media Manager

£27000 - £29000 per annum: Recruitment Genius: This is an opportunity to join ...

Recruitment Genius: HR Assistant

£17447 per annum: Recruitment Genius: This organisation is a leading centre fo...

Recruitment Genius: Trainee Case Handler

£15000 - £18000 per annum: Recruitment Genius: A Trainee Case Handler is requi...

Recruitment Genius: Junior Sales Apprentice

£15000 - £19000 per annum: Recruitment Genius: This is an opportunity to join ...

Day In a Page

Not even the 'putrid throat' could stop the Ross Poldark swoon-fest'

Not even the 'putrid throat' could stop the Ross Poldark swoon-fest'

How a costume drama became a Sunday night staple
Miliband promises no stamp duty for first-time buyers as he pushes Tories on housing

Miliband promises no stamp duty for first-time buyers

Labour leader pushes Tories on housing
Aviation history is littered with grand failures - from the the Bristol Brabazon to Concorde - but what went wrong with the SuperJumbo?

Aviation history is littered with grand failures

But what went wrong with the SuperJumbo?
Fear of Putin, Islamists and immigration is giving rise to a new generation of Soviet-style 'iron curtains' right across Europe

Fortress Europe?

Fear of Putin, Islamists and immigration is giving rise to a new generation of 'iron curtains'
Never mind what you're wearing, it's what you're reclining on

Never mind what you're wearing

It's what you're reclining on that matters
General Election 2015: Chuka Umunna on the benefits of immigration, humility – and his leader Ed Miliband

Chuka Umunna: A virus of racism runs through Ukip

The shadow business secretary on the benefits of immigration, humility – and his leader Ed Miliband
Yemen crisis: This exotic war will soon become Europe's problem

Yemen's exotic war will soon affect Europe

Terrorism and boatloads of desperate migrants will be the outcome of the Saudi air campaign, says Patrick Cockburn
Marginal Streets project aims to document voters in the run-up to the General Election

Marginal Streets project documents voters

Independent photographers Joseph Fox and Orlando Gili are uploading two portraits of constituents to their website for each day of the campaign
Game of Thrones: Visit the real-life kingdom of Westeros to see where violent history ends and telly tourism begins

The real-life kingdom of Westeros

Is there something a little uncomfortable about Game of Thrones shooting in Northern Ireland?
How to survive a social-media mauling, by the tough women of Twitter

How to survive a Twitter mauling

Mary Beard, Caroline Criado-Perez, Louise Mensch, Bunny La Roche and Courtney Barrasford reveal how to trounce the trolls
Gallipoli centenary: At dawn, the young remember the young who perished in one of the First World War's bloodiest battles

At dawn, the young remember the young

A century ago, soldiers of the Empire – many no more than boys – spilt on to Gallipoli’s beaches. On this 100th Anzac Day, there are personal, poetic tributes to their sacrifice
Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves

Follow the money as never before

Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves, reports Rupert Cornwell
Samuel West interview: The actor and director on austerity, unionisation, and not mentioning his famous parents

Samuel West interview

The actor and director on austerity, unionisation, and not mentioning his famous parents
General Election 2015: Imagine if the leading political parties were fashion labels

Imagine if the leading political parties were fashion labels

Fashion editor, Alexander Fury, on what the leaders' appearances tell us about them
Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

The architect of the HeForShe movement and head of UN Women on the world's failure to combat domestic violence