Phylogeny of The Genus Pterophyllum

The Origins of Taxonomy:
Classification has been around on earth ever since people paid attention to organisms. One primeval system that was developed was based on "harmful" and "non-harmful" organisms. Then, the beloved Aristotle was the first to form a useful system of classification during the 300s BC. His was first based on whether the organism had red blood or didn't have red blood. Then he subdivided organisms such as plants by physical characteristics such as size and features. This system is somewhat crude by today's standards, yet it lasted over 2,000 years. Eventually, as communication improved and science had advanced to a reasonable point, modern classification started to develop.

The most popular founder was the Swedish naturalist Carolus Linnaeus in the 1700s. He developed the system by which organisms are classified based on the unique characteristics that they had. He also invented the binomial nomenclature for naming. Linnaeus agreed with scientists that his work was somewhat crude, but it's purpose and general concepts were continually applied. Over time, as evolutionary studies were extrapolated, the classification system has become more advanced showing different groups and links. And as time goes on, classifications continue to change and are ever-growing. 

Introduction:
One of the most interesting fields of interest in the study of Biology is taxonomy. Although there are other fields out there such as ecology and embryology, taxonomy is easy to comprehend, restricted to a small set of structural information, and is good to know as reference. Taxonomy, also called systematics, is the study of the classification of all living organisms. The current method of taxonomy was started by Carlous Linnaeus which features organisms arranged into groups within groups within groups, on and on until an organism is defined within it's own species or individual group. This orderly classification helps scientists in a number of ways. One is that it keeps them clearly in sync with other scientists because of the existence of a universal system. It also helps scientists in identifying evolutionary links between certain species.

How it works:
Originally, when Linnaues founded taxonomy, organisms were divided based on sole visible physical characteristics. Now they're separated based on any unique and defining features mainly external physical features and secondarily based on other features such as feeding habits. Each organism is based on binomial nomenclature. This is in which an organism has two words to it's name. The first name is the genus and the second name is the specie. For example, humans are scientifically called Sapiens - genus Homo, species Sapiens. The words that make up the names for the individual groups of taxonomy are based on the Greek or Latin language. This makes for a universal language throughout the world. Otherwise an English scientist mentioning a "cat" to a Chinese person would be misunderstood because of language differences. There are international commissions out there that help filter and record an updated listing of the classifications. Some names are based on the equivalent characteristics of the organism in Latin, or they could have no meaning at all and are just named after their founder.

Kingdom: This it the largest unit of classification. Initially it was thought that there were only two kingdoms, plants and animals. Eventually microscope and other tools helped clarify the existence of other organisms. Now, there are a total of 5 kingdoms. Animalia - the largest with over 1 million named species, fish, humans; Plantae - 350,000 species, trees, grass; Fungi - 100,000 species, mushrooms, lichen; Protista - 100,000 species, green, golden, brown, and red algae, flagellates; Monera - 10,000 species, blue-green algae or cyanobacteria.

Phylum/Division: The next most specific unit of classification. This further divides the kingdom into 20 or so divisions based on very distinct and defining characteristics. For example, within the Animal Kingdom, a major division is the chordates that are animals with notochords. This includes humans, fish, mammals, etc. Flowering plants are defined into the antrophyta division of the Plant Kingdom.

Class: This further classifies the organism. It separates them into categories that make them very similar in terms of certain basic features. For example the class mammalia includes all animals that breast-feed, which includes humans, cows, dolphins, etc. Another class would be reptilia which includes cold-blooded and scaled animals.

Order: Organisms of the same order are more similar that that of the same class. A lot of obvious evolutionary connections can be drawn from looking at the order; only a few features separate the organisms as a breaking in the evolutionary chain. One example is that within the class Mammalia, carnivores are separated into the order Carnivora while Insect-eaters are separated into the order Insectivora.

Family: Even more specific, the animals within this share a very close similarity between each other. Most will probably have the same behavior patterns, feeding habits, and general functions. An example is the Cat Family (Felidaes) which all have whiskers, sharp claws, and include animals such as Lions and Cats.

Genus: This is the part that makes up the first word of the binomial nomenclature of an organism. All the organisms within their genus may look very similar to each other. And although it is at most times not healthy, organisms of the same genus may breed with each other.

Species: The most specific unit of classification is the species. The species makes up all the organisms and their apparent ancestors and descendants. Members of the species are much similar to their parents and can freely breed with other members of the same species without much complication.