Why are most living beings symmetrical in external appearance ? Are there any asymmetrical creatures ?

Question

Most of the livings beings look like can be cut into more or less equal halves.For example: Nose is on the middle and not on a side. Is symmetry a feature of on of our ancestors that we chose inherit ? If so who ?
Or is this symmetry deceptive but we are actually assymetric ?

Answer 1

I think it ties in with evolution and DNA. Copying errors with DNA can easily lead to duplication, but it's hard for them to lead to triplicates. The original split into left-and-right halves must have happened wayyyy long ago.

As for asymmetrical creatures, the fiddler crab comes to mind. Its ancestors probably were symmetrical at some point, but evidently there were evolutionary advantages to having one huge claw.

In a sense, all of us are asymmetrical inside when you start looking at the layout of internal organs. The heart is on the left side, and so forth.

Answer 2

I disagree with your premise. I think that all living beings are asymmetric. Im more precise though, because I think that one half of the nose is different from the other.

The "duh" answer is genetics.

My hypothesis is that there is a high-yield of function for a simple mathematical reflective symmetry, and so a little extra dna & tools leads to a whole lot more functionality.

Answer 3

Yes. But not permanantly. A flatfish is asymetrical during the stage that its eye begins to move to the other side of its body to join the other eye. Quite strange, no?

Answer 4

The flounder. A fish who lays on it's "side" which had it's "lower" eye flop up on it's "Upper" side so it could see better. A freaky thing, it is.

Answer 5

If you look closley we are different in minor ways but obviously we evolved this way because it works n the long run.

Answer 6

Atmospheric pressure I think