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For animals which lay eggs with shells, do most of them have the capability of laying unfertilized eggs? If so, do they follow some cycle like the menstrual cycle? If not, what determines whether they lay unfertilized eggs? Thieh ( talk) 00:42, 26 June 2014 (UTC)
All egg-laying animals initially produce unfertilized eggs in the hope that they will be fertilized. In the wild most of them get fertilized, but with birds such as chickens we artificially separate the males and females so that can't happen. I have read that chickens only keep laying if you keep removing the eggs so that they can't sit on a full clutch but I can't confirm that with a reliable source. It does say in our chicken article "Under natural conditions, most birds lay only until a clutch is complete, and they will then incubate all the eggs. Many domestic hens will also do this–and are then said to "go broody". The broody hen will stop laying and instead will focus on the incubation of the eggs (a full clutch is usually about 12 eggs)". There is an interesting discussion about laying unfertilized eggs here Richerman (talk) 09:48, 26 June 2014 (UTC)
Domestic chickens kept as layers have been selectively bred to produce lots of eggs. Also, they can only do so because the food we give them is designed to give them all the nutrients necessary for egg production - chickens kept for meat are given a different diet that is designed to produce muscle mass. Chickens tend to produce eggs during the summer months and stop laying as the days get shorter. To maximise production, commercially kept caged chickens are kept inside under artificial light with a fixed day length. If you think about other species such as fish or frogs they produce lots of eggs which are fertilized outside the body as they are laid - the chances are that some of these will not get fertilized. Queen Honey bees produce some unfertilized eggs and these develop into male drones. Richerman (talk) 16:00, 26 June 2014 (UTC)
I know this is slightly similar to the question about fridges above, but: In a hot room, not long ago, we had an air cooling machine, only it was located entirely inside the room, so no air could be transferred between it and the outside. The relevant articles are air conditioning#evaporative coolers, air conditioning#portable units and evaporative cooler, but there seems to be some confusion over terminology, since the first two sections I linked will both link to the article evaporative cooler. The first of those refers to models that exchange air with the outside; the second does not. I'm thinking about the second type. Am I right that it can only work for a brief period, because in a room full of people, the body heat will bring the temperature back to exactly the same equilibrium point, with a higher humidity? In other words, after the brief time for which the cooler works, the air should be just as hot, but more humid. Am I right? IBE ( talk) 05:18, 26 June 2014 (UTC)
In a closed, evaporative system, the dew point will rise in the room as the air saturates with water vapor and the air cools with the removal of latent heat. The higher the dew point, the lower the efficiency. Evaporative systems are usually open systems because the ambient air dew point is very low and doesn't rise. The difference between dew point and ambient temperature is similar to the temperature difference in a compressor-style air conditioner (the A/C temperature difference is constant and is affected by ambient temperature.) If you close off an evaporative cooler, the latent heat in the air that can be removed becomes less as the humidity/dew point rises. At the point where the dew point and air temperature are the same, the air is saturated and there is no more evaporative cooling. This temperature will be less than the the starting temperature and will happen as long as it's closed. Adding the heat of the motor/pump becomes a rate equation as to whether the system can add water as fast as the air can absorb it. -- DHeyward ( talk) 10:59, 27 June 2014 (UTC)
semicolon cancer? — Preceding unsigned comment added by 121.7.234.202 ( talk) 06:55, 26 June 2014 (UTC)
The excellent photo at the top of this BBC News page shows the inside of a Hippo's mouth very well. What are the interesting frilled structures to the left and right of the throat (just below the upper teeth) and what is their function? -- Dweller ( talk) 09:25, 26 June 2014 (UTC)
Geotechnical term. I believe it is limestone. However, I would feel more comfortable if this can be confirmed. Thank you 24.226.73.86 ( talk) 21:56, 26 June 2014 (UTC)
Science desk | ||
---|---|---|
< June 25 | << May | June | Jul >> | June 27 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
For animals which lay eggs with shells, do most of them have the capability of laying unfertilized eggs? If so, do they follow some cycle like the menstrual cycle? If not, what determines whether they lay unfertilized eggs? Thieh ( talk) 00:42, 26 June 2014 (UTC)
All egg-laying animals initially produce unfertilized eggs in the hope that they will be fertilized. In the wild most of them get fertilized, but with birds such as chickens we artificially separate the males and females so that can't happen. I have read that chickens only keep laying if you keep removing the eggs so that they can't sit on a full clutch but I can't confirm that with a reliable source. It does say in our chicken article "Under natural conditions, most birds lay only until a clutch is complete, and they will then incubate all the eggs. Many domestic hens will also do this–and are then said to "go broody". The broody hen will stop laying and instead will focus on the incubation of the eggs (a full clutch is usually about 12 eggs)". There is an interesting discussion about laying unfertilized eggs here Richerman (talk) 09:48, 26 June 2014 (UTC)
Domestic chickens kept as layers have been selectively bred to produce lots of eggs. Also, they can only do so because the food we give them is designed to give them all the nutrients necessary for egg production - chickens kept for meat are given a different diet that is designed to produce muscle mass. Chickens tend to produce eggs during the summer months and stop laying as the days get shorter. To maximise production, commercially kept caged chickens are kept inside under artificial light with a fixed day length. If you think about other species such as fish or frogs they produce lots of eggs which are fertilized outside the body as they are laid - the chances are that some of these will not get fertilized. Queen Honey bees produce some unfertilized eggs and these develop into male drones. Richerman (talk) 16:00, 26 June 2014 (UTC)
I know this is slightly similar to the question about fridges above, but: In a hot room, not long ago, we had an air cooling machine, only it was located entirely inside the room, so no air could be transferred between it and the outside. The relevant articles are air conditioning#evaporative coolers, air conditioning#portable units and evaporative cooler, but there seems to be some confusion over terminology, since the first two sections I linked will both link to the article evaporative cooler. The first of those refers to models that exchange air with the outside; the second does not. I'm thinking about the second type. Am I right that it can only work for a brief period, because in a room full of people, the body heat will bring the temperature back to exactly the same equilibrium point, with a higher humidity? In other words, after the brief time for which the cooler works, the air should be just as hot, but more humid. Am I right? IBE ( talk) 05:18, 26 June 2014 (UTC)
In a closed, evaporative system, the dew point will rise in the room as the air saturates with water vapor and the air cools with the removal of latent heat. The higher the dew point, the lower the efficiency. Evaporative systems are usually open systems because the ambient air dew point is very low and doesn't rise. The difference between dew point and ambient temperature is similar to the temperature difference in a compressor-style air conditioner (the A/C temperature difference is constant and is affected by ambient temperature.) If you close off an evaporative cooler, the latent heat in the air that can be removed becomes less as the humidity/dew point rises. At the point where the dew point and air temperature are the same, the air is saturated and there is no more evaporative cooling. This temperature will be less than the the starting temperature and will happen as long as it's closed. Adding the heat of the motor/pump becomes a rate equation as to whether the system can add water as fast as the air can absorb it. -- DHeyward ( talk) 10:59, 27 June 2014 (UTC)
semicolon cancer? — Preceding unsigned comment added by 121.7.234.202 ( talk) 06:55, 26 June 2014 (UTC)
The excellent photo at the top of this BBC News page shows the inside of a Hippo's mouth very well. What are the interesting frilled structures to the left and right of the throat (just below the upper teeth) and what is their function? -- Dweller ( talk) 09:25, 26 June 2014 (UTC)
Geotechnical term. I believe it is limestone. However, I would feel more comfortable if this can be confirmed. Thank you 24.226.73.86 ( talk) 21:56, 26 June 2014 (UTC)