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Physics, Astronomy & Cosmology / Re: Does planet size determine life form size?

« on: 03/02/2012 08:19:39 »

Nice rhetoric Don_1. Just sone additional comments:

A dinosaur (Sauroposeidon) might have weighed 60 tons. But since these huge animals disappeared with the demise of the dinosaurs, one has to wonder if perhaps the Elephant is the largest practical size for a terrestrial creature, since the only bigger animals which have fared so well are those which are aquatic.

The fact that we don't see animals with the size of dinosaurs has nothing to do with practical size, but rather with the Oxygen percentage in our atmosphere. In the dinosaur era it was much higher than it is now, so in Earth's ecological system, O₂ concentration is a limiting factor to the size of land animals.

A planet with the gravity field of Jupiter might be unable to support life due to the size an animal would need to be to be strong and resilient enough to survive the crushing effect of both the atmosphere and the gravity itself. Too small and bone/cell strength might be insufficient, but as size increases to accomodate greater strength, so the need for still greater strength increases.

You're only thinking of our known Calcium-based skeleton now. Who's to say that animals who evolve under higher gravity pressure don't evolve with a skeleton made of sturdier materials?

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Physiology & Medicine / Why Do I Sometimes Miss A Word From A Written Sentence ?

« on: 15/11/2011 06:18:39 »

Simple answer: Your brain is much faster than your hands.

Your tongue is also faster than your hands, that's why you'll never have this happen when you speak, only when you write.

Try to do this experiment: Notice what word is in your head while typing a sentence. You'll notice that the word in your head is often a couple of words further along the sentence than the one you are typing at that moment

So it's easy for your hands to skip a word sometimes. This isn't dyslexia in my opinion..

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Chemistry / A Chemicals Point Of View !

« on: 17/12/2009 11:59:55 »

Pentacene: The first picture of a molecule's anatomy. Made bij an Atomic Force Microscope with a CO molecule at the tip.

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Plant Sciences, Zoology & Evolution / Why is natural selection so much slower than human-led selection?

« on: 15/09/2009 08:57:03 »

SOOOOOooooh,

on topic: Natural selection is much slower than human selection because natural selection occurs at random, and human selection has some reasoning and purpose behind it.

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Plant Sciences, Zoology & Evolution / How do cold-blooded species cope in cold water?

« on: 18/08/2009 10:23:00 »

For an important chemical reaction, poikilotherms [cold-blooded animals] may have four to ten enzyme systems that operate at different temperatures. As a result, poikilotherms often have larger, more complex genomes than homeotherms [warm-blooded animals] in the same ecological niche. Frogs are a notable example of this effect.

Because their metabolism is so variable, poikilothermic animals do not easily support complex, high-energy organ systems such as brains or wings.[citation needed] Poikilothermic animals do not use their metabolisms to heat or cool themselves. For the same body weight, poikilotherms need half to 1/10 of the energy of homeotherms, and thus eat half to 1/10 of the biomass.

source: http://en.wikipedia.org/wiki/Poikilotherm

So to answer your question: They have specialized enzymatic systems.