Welcome to Introduction to Scientific Names


In more technical literature, an organism is typically referred to by its scientific name. In contrast with common names, a scientific name is the same in any language and provides a unique name for an organism such that two people can be sure that they are referring to the same organism.  This is not so with common names, e.g., "bream" refers to one kind of fish in some parts of the country, but completely different fish in other parts of the country. Following is an introduction to scientific names.  Because many scientific names are constructed from Latin or Greek roots, you may find this guide to root words a useful tool for understanding scientific names.

The Problem

With so many species on this planet, it is essential to have a way to keep track of all of them, hence scientific names.  As some of you may recall from a biology course, it was Carl Linnaeus who gave us our current system of “binomial nomenclature”.  While you may curse it at times, consider what it replaced, namely a system where one species might have a name consisting of a single word, while another might bear a whole phrase as its name, something along the lines of “the fish with little yellow spots on a blue body”, except in Latin.

The old approach was haphazard and cumbersome, and so Linnaeus sought to clean it up.  Every species would get a name consisting of two words: the first word was the genus, and the second word was a specific epithet, and that couplet would together uniquely identify the species. This approach reflected the idea of hierarchical structure, namely that a family consisted of potentially a number of genera, and so each of these was to be named, and that a genus consisted of potentially a number of species and so the specific epithet would narrow the identification down to just one species within that genus.

So the problem was solved.

Getting to the roots

But wait, two simple words do not provide a lot of flexibility nor descriptive power, and there are so many organisms on this planet (10 million plus and counting). So, simple words would not do the trick; instead each word tended to be a compound structure composed of one, two or more combining forms, called roots. A typical root is micro-, meaning small. There are many roots that describe sizes and/or shapes of attributes or characters.  The eye is a typical fish character and the root opthalm is a Greek root meaning eye.  By combining micro with opthalm  we get micropthalmus which means small eye, and is a rather nice description of a particular cichlid from Central America, i.e., Theraps micropthalmus, which appears to have an unusually small eye compared to similar species.     

While it can be difficult to master so many fish names, it is much easier to master a list of roots and then recognize how longer words are put together.  

In fact, you probably already know lots of roots and use them from time to time without really appreciating their origin. This is particularly common when dealing with aches and pains and other medical conditions. For example, once you know that arthritis is inflammation (-itis) of the joints (arthr-), then bronchitis is simply inflammation of the bronchii (lungs), and laryngitis is inflammation of the larynx (voicebox). Add to this the knowledge that -pod means legs and it is an easy next step to see that arthropod means jointed legs. A quick look at a lobster reveals that it fits nicely into the category of arthropods, a group of animals characterized by their many jointed legs.

By building up a mental network of combining forms (or roots), a person can understand a huge amount of scientific and medical terminology and still have some brain-space left over for other subjects.

Where  do these roots come from?

Some of these roots derive from ancient Latin or Greek and some from other languages (increasingly so in the scientific names of organisms). Latin derived from Greek and Greek derived from the earlier Phoenician language. Because of these multiple ancient and confusing origins there are sometimes alternative ways of saying essentially the same thing, e.g., nephric and renal both mean "pertaining to the kidney" but the first is Greek and the second is Latin.  

Other roots are modifications of the names of people, places, or worse yet, other things (see below).

Because of the diverse origins of these words, while many biologists will speak of the "Latin name" of an organism, it is more appropriate to speak of the scientific name of an organism, rather than its Latin name.

The science of  names

The science of naming biological things is called taxonomy. Taxonomy is far from simple. In fact, there is an entire, very complicated, book devoted to all the rules that must be followed when giving an organism a name. It is called the International Code of Zoological Nomenclature. It is revised periodically and the latest edition, the Fourth, was published in 1999. The book reads much like a lengthy legal document, detailing all the possible cases and considerations. Keep a copy handy if you ever have trouble sleeping!

As stated, the full name of a species is given as two words: its genus (always capitalized) followed by the specific epithet (never capitalized), e.g., Urusus americanus, the black bear. Although the use of italics in print means, by convention, that the italicized word is a Latin word, scientific names are traditionally printed in italics, regardless of whether the name is derived from Latin or not, e.g., Lepomis macrochirus is printed in italics even though the specific epithet, macrochirus -- meaning large hand -- is derived from Greek.
Scientific names have traditionally been based on Latin or Greek roots, although more recently, roots from other names are allowed and being used, e.g., Oncorhynchus kisutch. The root Onco is Latin for hooked and rhynchus is Latin for beak, i.e., hooked beak. kisutch is a Russian word. Oncorhynchus is the generic name for Pacific salmonids, and is very appropriate, given the hooked beaks Pacific salmonids have when breeding. Oncorhynchus kisutch refers to the coho salmon which is found on both sides of the Pacific Ocean, in North America and in Russia.
The Endings

Because the root may have a gender associated with it, the specific epithet is supposed to agree with the gender of the root (where possible). This may cause the specific epithet to change if an organism is moved from one genera to another. So for example, the convict cichlid (one of my favorite study animals) used to be called Cichlasoma nigrofasciatum. But, when the species was moved to the genus Archocentrus, the specific epithet had to change to nigrofasciatus, so the fish is now called Archocentrus nigrofasciatus. Notice the change from um to us on the end of nigrofasciatus.  

This change is really important because some people may not realize that nigrofasciatus and nigrofasciatum are the same animal.


An ideal scientific name helps the reader know something about the organism being discussed, e.g., the specific epithet, leptocephalus tells you that the animal has a slender (lepto-) head (-cephalus). Other scientific names incorporate a person's name, a location or some other combination of letters. If you are unfamiliar with the name it can be frustrating to try to interpret these names if you do not recognize that they are not traditional Latin or Greek roots.  

For example, Pseudotropheus barlowi is the name for a golden yellow fish found in East Africa; however, barlowi does not mean yellow. Rather, it pays homage to George Barlow, a famous ichthyologist and former PCCA member who spent much of his career trying to understand the prominent gold color found in some fishes. Similarly, Bufo californicus (the Arroyo toad) comes from California. The specific epithet of Tomocichla asfrasci, a beautiful fish from Panama, is actually an acronym for the Association of French Cichlid Aquarists, the group that sponsored the research that discovered the fish. Such names are discouraged but nonetheless they do exist.

Sometimes names are not terribly appropriate. This may occur when the person describing an animal (i.e., writing the formal description) is not all that familiar with the animal in life. The describer may be working solely from preserved specimens. For example, in the name of the fish Archocentrus septemfasciatus, the specific epithet means seven striped. Unfortunately, the animal involved only shows its seven stripes very, very rarely, namely when it is highly stressed, as it might well be when dropped into formalin!  The rest of the time, this fish typically shows no stripes at all, and when it is breeding it shows three spots.  Perhaps a better name would have been Archocentrus trimaculatus, however, once an animal is named, provided the rules have been followed, the name sticks and cannot be changed just because the name is not appropriate. One of my favorites is Labidochromis coeruleus. The specific epithet means blue, but the fish is a bright, golden yellow.  Oops!  

Similarly, Hypomesus transpacificus (the Delta smelt) suggests a fish found across the Pacific, i.e., on both sides of the Pacific ocean. Unfortunately, the name was given before it was recognized that the smelt found in Asia is completely different from (and only distantly related to) the Delta smelt which, in contrast to its grandiose name, is found only in the upper estuary of San Francisco Bay, a very restricted habitat indeed.  

The bottom line is that scientific names are often useful, but they can also be misleading.

Making scientific names

The simplest way to make a name out of a root is to add the suffix "a", "us" or "um" to the end of the root (depending on the gender), e.g., for a spotted animal, use maculata, maculatus or maculatum.  

Often, however, one root is not enough to clearly identify the organism and you want to elaborate. So, you might combine two roots, e.g., eight spotted, becomes octomaculatus. This combines the root oct- with the root maculat- and the suffix us. To put the roots together we add an "o" in between (other times we might use an "a" or an "I" depending on the root). The "o" or "I" is called the combining vowel.

Note that there are other possible suffices besides "a", "us" and "um"; these are the ones you will see most often in scientific names.

When you are combining these parts together, we try not to mix languages within a word. For example, we say hepatic meaning "pertaining to the liver", not hepatal. The root hepat/o is Greek and the suffix meaning "pertaining to" in Greek is -ic. While the suffix -al also means "pertaining to", it is Latin.

It gets harder if there are both Greek and Latin roots for the same structure, e.g., nephr/o is Greek while ren/o is latin.  So we would say renal but never renic and we would say nephric but never nephral.  

Besides suffixes, roots and combining vowels, you may see prefixes. A commonly used prefix is a, meaning "without", as in asexual which means "without sex".

Just to mess with you -- actually it is more a matter of easing pronunciation -- some prefixes change when placed in front of certain letters. This is called assimilation. For example, the prefix syn (= fused or together) when added to the root -pathy (= suffering) becomes sympathy not synpathy. Perhaps most intriguing is the word assimilation which is created by combining ad and similation, and is in fact an example of assimilation, i.e., it is NOT written adsimilation.

Scientific names at higher taxonomic levels

There are fewer rules for names at higher taxonomic levels, largely because these names do not really mean much.  However, there are a few conventions. For example, the names of biological families of animals always end in idae, e.g., Cichlidae is the name of the family containing the cichlid fishes. Notice that the family name is capitalized, but not italicized. You may refer to the members of the family by removing the "ae" and adding "s" and not capitalizing, e.g., cichlids are wonderful aquarium fishes.  

        inae – subfamily, e.g., Cichlasominae
        idae – family, Cichlidae
        oidea – suborder, e.g., Labroidea
        iformes – order, e.g., Perciformes


I do not think it matters exactly how you pronounce these words. In fact, I think it is difficult to argue that there is a correct pronunciation for words formed from the composite of various languages, some of which are no longer spoken. For example, Oncorhynchus kisutch is a combination of Latin and Russian and it seems unnecessary to switch accents halfway through the name.  

Far more important than the exact pronunciation is that you annunciate all the parts such that a listener has some hope of understanding the roots. Too often, beginners, when confronted with a lengthy scientific word, speed through it in hopes that if it is said quickly, any mispronunciations will not be noticed. However, in speeding through, the hasty orator often leaves out or alters some of the roots, thereby changing the meaning of the word. For example, antilocapra means "antelope goat" (antilo- = antelope; -capra = goat). If you say the word too quickly and drop the lo part, it sounds like anticapra which would be "opposite of goat". The species Antilocapra americana is the Pronghorn which indeed does look like a cross between an antelope and a goat found in western North America  and so it is important to pronounce all the syllables. Because of this danger, I appreciate when people say scientific names slowly and clearly, annunciating each part.

That said, there are conventional ways of pronouncing these words, often learned by hearing a mentor. Once learned, it is difficult to change one's pronunciation of a particular word. Micropterus punctulatus (the spotted bass, a kind of sunfish native to the central United States but now found in California)  is pronounced by some as Microp-terus. This is fine but it may confuse the listener because the roots that make up the word are micro- and -pterus which literally mean "small-wing". The p in terus is silent. There is no Latin root microp-. I prefer to pronounce each root, i.e., Micro-pterus, so that the origins and meaning of the word are clear.


To learn more about Latin and Greek roots and scientific names, there are numerous books on those topics. One little book that I find particularly useful is a classic little pocketbook by D.J. Borror,

    Borror, D.J. (1988) Dictionary of Word Roots and Combining Forms. Mayfield Publishing, Mountainview, California. 134pp.

It costs around $11 and simply lists hundreds of Greek and Latin roots and their associated meanings.