What am I? Taxonomic Ranking Explained
If it has been awhile since high school biology, or maybe you never even took biology at all, you may be confused about all of this genus, species stuff. What does it all mean? How does it fit together? Here is taxonomic rank explained.
All living organisms are 'ranked' on various levels going from the broadest to the most specific. This ranking system is known as the taxonomic rank or taxonomic hierarchy. It enables us to understand the specific features that a chosen organism has, and compare that organism to others in the same category or closely related categories. The more rank levels that two creatures have in common, the more similar they are.
With the improvement of DNA analysis and genome mapping, some surprises have been revealed, which has caused slight adjustments to the traditional placement of creatures within the ranking system. Overall, however, the system remains largely useful for biologists and zoologists pursuing knowledge about a particular species.
The broadest category is the domain. There are generally considered to be three domains of life, although some scientists suggest that viruses should be a fourth category. The three existing domains are Archaea, Bacteria and Eukarya. Archaea and Bacteria both consist entirely of single-celled (prokaryotic) organisms, and differ in their chemical compositions. Eukarya contains all multi-celled (eukaryotic) organisms.
The next rank down from domain is kingdom. There are 5 kingdoms - Animalia, Plantae, Fungi, Protista and Monera. However, there is debate about the proper number of kingdoms and what should be placed in which kingdom.
Below kingdom is phylum. The Animalia (animal) kingdom contains 35 phyla, where the Plantae (plant) kingdom contains 12. One of the phyla for Animalia is Chordata. The chordates have 'hollow dorsal nerve cords.' In other words, some form of a nerve system running along their back. Humans are chordates, as seen by the existence of our spinal cord.
Below phylum comes class. Humans are members of the class Mammalia. Mammals are, amongst other things, characterised by their possession of mammary glands. Mammary glands are used to produce milk to feed their young.
Order comes after class. There are many orders for Mammalia. Humans are members of the order Primate, characterised by the presence of opposable thumbs and large brain to body ratio.
Next is family. The Primate order begins to get very complicated, but essentially is split into multiple families. Humans are in the family Hominidae.
Below family is genus. Humans are in the genus Homo. The other extant (still living) genera from the Homindae family are Pongo (orangutans), Gorilla (gorillas) and Pan (chimpanzees).
Finally, we have reached species. Humans belong to the sapiens species. Therefore, we are Homo sapiens. Humans are the only existing member of our genus, as all other Homo groups were our ancestors or contemporaries from millions of years ago and have long gone extinct. One helpful way to remember the order of the ranking system is the phrase: Dear King Phillip Came Over From Greece Singing... Kingdom, Phylum, Class, Order, Family, Genus, Species. Feel free to come up with other fun ways to remember!
