Because evolution is not about “best” or “most organized” but about “good enough.”
There isn’t an advantage to having an addition set. It would cost more energy to create. And there isn’t a disadvantage to having the number of sets they currently have.
This is a tough one and there’s no proof either way, but the only answer I could find that makes sense is that:
Centipedes embryos grow in segments from the head back. But crucially, it’s in pairs of segments. So the total number of segments is always a multiple of 2, i.e. even.
Why is it always an odd number of pairs of legs then? Most likely, the head segment is included in this growth, and the mandibles are genetically derived from legs. Include the jaws and it’s always even.
Centipedes gestate in two segments at once. This means it would be an even number, since each segment has one pair of legs. But it is believed that one of the claws they use for hunting is a modified segment, meaning the first pair of segments developed only has one pair of legs attached. That makes it always odd.
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Because evolution is not about “best” or “most organized” but about “good enough.”
There isn’t an advantage to having an addition set. It would cost more energy to create. And there isn’t a disadvantage to having the number of sets they currently have.
This is a tough one and there’s no proof either way, but the only answer I could find that makes sense is that:
Centipedes embryos grow in segments from the head back. But crucially, it’s in pairs of segments. So the total number of segments is always a multiple of 2, i.e. even.
Why is it always an odd number of pairs of legs then? Most likely, the head segment is included in this growth, and the mandibles are genetically derived from legs. Include the jaws and it’s always even.
Centipedes gestate in two segments at once. This means it would be an even number, since each segment has one pair of legs. But it is believed that one of the claws they use for hunting is a modified segment, meaning the first pair of segments developed only has one pair of legs attached. That makes it always odd.
Why do you only have an odd number of pairs of legs??