Their special property turns out to increase their chance of being reproduced. That alone probably explains why they are found in so many species. If they happen by accident, they aren't likely to go away. And, they have all the right properties for making the occasional jump from one species to another. Taxonomy Fitting organisms into an organizing scheme is referred to as taxonomy .
Biologists use the Linnean scheme for giving names to species.
Vertebrate An animal with a nerve cord enclosed by a backbone made of vertebrae. Fish, amphibians, reptiles, birds and mammals are vertebrates. Email a comment.