Main content
Course: How we organize life to study them? - Class 11 > Unit 2
Lesson 1: Nomenclature and taxonomyBinomial Nomenclature
How organisms are named scientifically.
This article enumerates the rules of scientifically naming living organisms.
Key terms
| term | meaning |
|---|---|
| Binomial nomenclature | System of scientifically naming organisms with two words |
| Genus | The taxonomic category above species |
| Species | The most basic taxonomic category consisting of individuals who can produce fertile offspring |
The need for scientific naming
Which is the biggest land animal in the world? The answer is easy - the elephant. However, not everyone calls it the elephant. It is called haathhee in Hindi, da xiang in Chinese, aane in Kannada, slon in Russian, and the list goes on. For scientific communications, we need a common system of naming organisms, so that everyone calls an organism by the same name regardless of their region or language.
Binomial Nomenclature
Carolus Linnaeus, a Swedish Botanist of the 18th century, came up with a simple solution, the system of binomial nomenclature. As the name suggests, this system of naming consists of two words for each organism. The first word is the name of the genus, while the second word is the species. Both words are italicized, and the first letter of the first word is capitalized.
Let us take the example of the elephant again.
The scientific name of the Asian elephant is Elephas maximus. Here "Elephas" is the name of the genus, and "maximus" is the species.
The African bush elephant is a different organism altogether, its scientific name being Loxodonta africana.
What if we are hand writing the scientific names? Since we cannot italicize words while writing by hand, we underline the words separately:
Sometimes, to save time, the is shortened to the first letter, followed by a fullstop:
L. africana
The generic and the species names have been traditionally derived from Latin, but there can be other sources too, including classical Greek, and even names of places and people.
Sometimes, the species name is not specified, and the unspecified species is indicated by the abbreviation "sp.", which is not italicized. For example, there is another species of the African elephant called the African forest elephant. Its scientific name is Loxodonta cyclotis. This means that it belongs to the same genus, Loxodonta, as the African bush elephant.
If we just want to talk about the genus Loxodonta without specifying the species, we can write Loxodonta sp.
The naming of plants follows the same rules as animals and other organisms. Often, for plants, the name of the scientist is added in an abbreviated form after the scientific name. For example, the scientific name for the mango tree is Mangifera indica L., where "L." stands for Linnaeus, the person who created this name.
Scientific names of common organisms
The following table gives the scientific names of some organisms.
| Common name | Scientific name |
|---|---|
| Sore throat bacterium | Streptococcus sp. |
| TB bacterium | Mycobacterium tuberculosis |
| Malarial parasite | Plasmodium sp. |
| Amoebiasis pathogen | Entamoeba histolytica |
| Bread mold | Rhizopus sp. |
| Mildew | Cladosporium sp. |
| Rose plant | Rosa sp. |
| Tomato plant | Solanum lycopersicum |
| Silk moth | Bombyx mori |
| Giant panda | Ailuropoda melanoleuca |
To summarize, these are the rules of writing scientific names.
- There are two words, hence this system of naming organisms is called binomial nomenclature.
- The first word is the name of the genus, and the second word is the species name.
- Both the words are italicized.
- The two words are underlined separately when hand-written.
- The first letter of the genus name is capitalized, everything else is in small letters.
- The genus name may be abbreviated to just the first letter.
- Sometimes, the name of the species is replaced by "sp.", which refers to all the species under the genus.
- For plants, the binomial scientific name is often followed by an abbreviated form of the name of the scientist who named the plant.
Want to join the conversation?
How much have Asian elephant numbers declined in the last three generations?(2 votes)
why can't hybrid offspring animals breed with other hybrid offspring animals?.(1 vote)
it's because they can't produce sex cells / eggs / sperm. this is because when two different species form a hybrid, the chromosomes of the hybrid don't really line up because of the huge difference in their parents. so, they can't breed with the others.
edit: just found out female ligers can mate with lions (not usually, though), because only the male ligers are sterile. i suggest you go read about it :)(1 vote)
I've seen some binomal names followed by a var. "something". Example Amanita muscaria var regalis. Is this var category really a level below species again?(1 vote)