Managing an odd number of limbs is more difficult.
Some marine invertebrates, such as starfish, have an odd number of rays — most often five. However, these are more like body parts than actual limbs. In terrestrial vertebrates, limbs evolved from paired organs, specifically from the pectoral and pelvic fins of fish.
Nevertheless, even in terrestrial creatures with different limb origins, the number of limbs always remains even. This is likely related to the difficulties of managing an odd number of limbs. However, in vertebrates, there are cases of an odd number of legs. This rare anomaly can be caused by various factors, such as genetic mutations, disruptions in embryonic development, or the influence of certain parasites.
