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Mentat
X-Ray Wave
USA
1269 Posts |
 Posted - 02/24/2003 : 19:15:20
There are certain animals that are not said to have changed much, over the course of thousand of years - in which all of the other animals are supposed to have been evolving. An example is the shark. I was just wondering if anyone could think of some other examples, and maybe why their so perfect (IOW, what characteristics do they have, that make them so fit for survival?). The shark is obviously well fit for survival, but there are others.Any/all responses are appreciated.
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Edited by - Mentat on 02/24/2003 19:16:03
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STAii
X-Ray Wave
Jordan
1376 Posts |
Posted - 02/24/2003 : 20:40:03
I think turtles didn't change a lot over the last few thousand years.
That is because the turtle (first of all) has its shield (do you call it this way?) which protects it in various enviroments, therefore it does not need to evolve for each new enviroment.
I think that another reason may be the long life-cycle of the turtles, therefore having a smaller chance to actually evolve (i am not sure of this one ..)
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voyeur
Visible Light Wave
USA
577 Posts |
Posted - 02/24/2003 : 22:43:57
Mosquitos and cockroaches have been around for millions of years. There is also a fish called the coelacanth that was only known through fossils until one was caught early last century, the fossils are also millions of years old. There are probably a couple of things we haven't discovered yet. Maybe the stories of a brontosaur like dino in the congo (Mokele-mbembe) are true. There are also stories of something in south america that could be a giant sloth. The movie 'the lost world' is based on plateaus (tepui) in venezuala where sightings of dinosaurs have been reported.There are probably many reasons why a particular animal survives that long. Lack of competition in it's environment or it's better than any competition. It is symbiotic with it's environment. It is almost a perfect design like the shark (it was perfect until we came along). A high birth rate can be a good survival tactic under certain circumstances (which don't apply to us). There must be others.
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Phobos
PF Mentor
USA
1417 Posts |
Posted - 02/24/2003 : 23:30:47
We can cite many life forms that appear unchanged (based on casual observation) over long time periods. But they're still evolving. Even if gross anatomy is essentially the same (like the shark, etc.), there are many minute changes such may not be apparent. This can be physical (e.g., millimeter-level changes in the beaks of the finches on the Galapagos islands from year to year) to invisible changes like immune system or metabolism variations. And that's just alleles (expressed genes).Point is, the rate of evolution can vary. --------------------------
In the fabric of space and in the nature of matter, as in a great work of art, there is, written small, the artist’s signature. (from Sagan's "Contact")
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Another God
X-Ray Wave
Australia
1683 Posts |
Posted - 02/25/2003 : 11:41:34
The easiest way to see which critters have evolved over the last many many thousands years into essentially the same form as they were way back, is to look at designs which are essentially the same on all of the continents, yet couldn't physically spread over those distances in recent years.my best example would be the crocodile/alligator. They are on every continent that has their climate, and they are all very similar. Ants. Cockroaches. Prove me wrong, I might learn something.
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