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"The beginning of wisdom, as the Chinese say, is calling things by their right names."
When a fishkeeper sees a new fish, the first question most frequently asked is "what is the name of that fish". It is in the nature of most aquarists to want to classify and name every fish that he/she maintains or studies. In addition, biologists need to know the correct name of a fish when consulting work already carried out by others. Also, the use of the scientific name by all nationalities permits universal recognition.
Common names are not reliable; they are not consistent and are very loosely applied. The scientific name doesn't have to be used all the time, since short common names serve well for common animals and plants. However, to identify an organism unmistakably, the scientific name is necessary.
To this end a complicated scientific identification system has been developed to try to match the extraordinary complexity of nature. By using the scientific name of a fish you can be sure that everyone is talking about the same species. This is why name changing by taxonomists often irritates aquarists.
The current system owes its origin to the father of modern classification or taxonomy; a Swede named Carl von Linné (1707-1778). He is better known by the Latinised name that he adopted, Carolus Linnaeus. Linnaeus introduced the hierarchy from broadest to most specific which today with some amendment consists of a "kingdom", "phylum" or "division", "class", "order", "family", "genus", and "species".
Linnaeus devised a naming system for species that is still in use today. The complete species name is comprised of the generic (genus) name and the specific (species) name. The genus is named first and is capitalised followed by the species, which is not. Both the genus and species are often italicised. It is customary to add the name of the author of the species and the date of publication, for example, Melanotaenia angfa Allen, 1990. Brackets around the author's name, for example, Melanotaenia nigrans (Richardson, 1843) indicates that, although the original description is accepted, the generic name is no longer valid and has been changed since the species was first described.
Sometimes you will see the generic name of an organism with sp. or spp. after it, for example:
- Melanotaenia sp. means a species of the genus Melanotaenia;
- Melanotaenia spp. means species of the genus Melanotaenia (ie more than one).
This custom is followed when you can identify the organism (or organisms) to genus level only.
The words drawn upon for scientific names are mainly Latin or ancient Greek (both defunct languages and therefore not undergoing continual change) and the rules of Latin grammar apply. Scientific names are often based on the appearance of the species or include the name of people or places associated with the discovery. A scientific name is not accepted until it appears in print with a full description of the species.
The only taxonomic unit taxon (plural taxa) that actually exists in nature is the species. The species is the lowest taxonomic category and, indeed, is the only 'true' biological one; that is to say, the species is recognised as the living thing upon which natural selection operates. Species that are very similar are placed in the same genus. Similar genera are then placed in the same family and families are grouped into orders and classes. Above this the classification is subphylum and phylum (plural phyla) for animals, and division for plants. (Species is either singular or plural; specific is the adjectival form. Genus is singular, genera is plural, and generic the adjectival form.)
There is much argument and discussion amongst biologists as to what a species actually is. The classic definition of a "species" is related organisms that share common characteristics and are capable of interbreeding and producing fertile offspring. Ideally biologists study the genetics of the individuals, carry out cross-breeding experiments and search in nature for evidence of breeding between two populations before deciding a population represents a species. However, this has high practical difficulty and is only done occasionally.
Many consider appearance in separating species. "This fish looks exactly (or almost exactly) like that one, therefore both are likely to belong to the same species". This is a rather simplistic view of the species concept, which, in practice, is much more complex because a species may comprise several populations or varieties within a species.
The system of classifying species may seem very scientific. But in fact, the system involves much human judgment and there is dispute and uncertainty about it. It is a system in constant flux as new knowledge is discovered. Perhaps the most modern and significant means of differentiating species is through the increase in our knowledge of genetics. It is now possible to sequence and compare the genes in different species. However, whenever new knowledge is developed, there will always be realignments in the classification system and disputes will arise.
Rainbowfish taxonomy example:
Phylum - Chordata
Class - Osteichthyes
Order - Atheriniformes
Family - Melanotaeniidae
Genus - Melanotaenia
Species - trifasciata
© Copyright Adrian R. Tappin
Created July, 2005.
Updated January, 2007.
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