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Question of the Week / QotW - 11.12.11 - Do fish enjoy reproducing?

« on: 11/12/2011 14:46:13 »

Not everything we do requires that we derive pleasure out of it. For example, not too many people get great pleasure out of breathing, yet we do so anyway. it can be hard to sometimes put a line between pleasure and some sort of biological instinct but we can look at some breeding practices and see that not all creatures find it "pleasurable".

• Many animals die right after mating. Reproducing takes a lot of energy, so there can be an advantage if a creature can give everything it's got to the next generation. Salmon and most octopuses fall into that class.
• Some animals allow themselves to be consumed by there mates. Spiders are an excellent example. A nitrous snack for the female can ensure that she has enough energy to lay her eggs. Plus as long as the female is munching on the male, she's not mating with someone else.
• For the title of least pleasurable mating practice, look no further than the male grouper fish.  Male grouper fish are born immature and never fully developer. They can't even eat. Their sole task is to locate a female group who is 30 to 100 times his size and bite her and hold on. Soon their jaws and mouths disappear and blend into the female. Their body organs deteriorate, and all that's left of the male is his reproductive organs hanging off The female's body.
  
  When scientists first started investigating groupers, they realized all they saw were females and never a male. And all the females had these "tumors" all over them. Only later did they understand that those tumors were the remains of various males.
  
  Scientists speculate that this mating practiced probably developed because groupers are not that common in the deep sea.  It would be highly unlikely for a male and female to meet up when the female is breeding. Therefore, a male becomes part of the female and his sperm are there whenever the female is ready to breed.

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Physics, Astronomy & Cosmology / Re: Can jumping upwards enable you to survive in a falling lift (elevator)?

« on: 10/08/2007 04:19:00 »

Since the lift is falling at the same speed as you are, you'd find it pretty hard to jump. Bending your knees won't bring your body any closer to the floor, but would probably cause your legs to lift off the floor. You simply couldn't bend down to jump.

If somehow you did manage to propel yourself upwards (maybe pushing on the railing on the side), you'd have to be strong enough to be able to fling yourself several stories off the ground (Imagine being able to push yourself off a railing and jumping 6 to 12 meters in the air). If you could do that, you'd probably be Superman, so you would merely fly out of the falling lift, race downward at the speed of light and stop the lift from falling to the ground. Even better, you'd orbit backwards around the earth -- causing time to go backwards -- and post a note on the lift the day before that it's out of order.

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General Science / Why do my bike tyres go flat when I don't use it?

« on: 30/07/2007 04:23:23 »

All tires leak air. Rubber is composed of long elastic fibers, and there are gaps between the fibers where air escapes. That's why a rubber helium balloon will quickly lose its ability to float after a day or two while a mylar balloon will stay up for a week or more.

When you put a bike in the garage for a few months, the tires leak air, and no one is topping up the tire when they notice it is low. By the time you take it out of the garage, it is completely flat. If you constantly are riding the bike, you're constantly topping off the tire whenever you notice it is a bit low, and that tire never goes flat.

Therefore, when you constantly ride a bike, the tire never seems to go completely flat. But, when you don't ride it after a while, it goes completely flat.

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Physiology & Medicine / why does the left side of the brain control the right side of the body??

« on: 01/05/2007 02:18:44 »

I have a theory. Vertebrates differ from other creatures like insects in their location of their nervous system. Vertebrates' spine is along the back, but insects have a network of nerves on their bellies. A recent study in Cell magazine (synopsis is here: http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&SESSION=&RCN=27545) locates the common ancestor as the lowly marine worm.

The question becomes how did the nervous system switch from the front of the creature to the back. Detlev Arendt of the European Molecular Biology Laboratory in Heidelberg (who produced the paper in Cell) has a theory. Imagine a filter feeding worm that eventually became the ancestor to all vertebrates. Dr. Arendt envisions this creature half buried in the sea floor with its belly and nervous system protected by boney plates. One day, this creature leaves the safety of the sea floor to swim around -- upside down. Since the creature is in water, up and down has no real significance, so it simply adopted to its new posture where its former belly became its back and its back, its belly. (see http://www.economist.com/science/displaystory.cfm?story_id=9033083 in the Economist near the end of the article).

If this happened, and the creature turned its head 180 degrees in order to adjust to this body plane, then the right side of the body is now controlled by the left side of the head and the left side of body is controlled by the right side of the head.