It may be hard to imagine but taxonomy, the science of classifying organisms, is going through big changes. Most of us think that once an organism has been classified it’s over, done, finished! Not necessarily.

For centuries taxonomists, the scientists who classify organisms, have used observable characteristics including:

• Morphology – the structure of an organism
• Reproduction – the process by which an organism reproduces itself
• Function – the use or action of specific body parts
• Habitat – the environment in which an organism lives
• Behavior – response to specific stimuli
• Heredity – acquired genetic traits

Recent advances in DNA and RNA sequencing have resulted in major reevaluating of past classifications. Micro-organisms previously grouped by structure, habitat, and reproduction are now being split into new groups or lumped together in groups that seem to have little in common, other than their DNA or RNA.

In the past century, the process of classification hasn’t changed much. Organisms are still “keyed” into the taxonomic hierarchy based on how closely related they appear to be. This taxonomic hierarchy begins with Domain or Kingdom and proceeds through Phyla, Class, Order, Family, Genus, and species.