Archive for September, 2008

Please welcome back Eileen with another excellent post.

What do you call the fizzy, carbonated drinks sold in cans and bottles and out of vending machines by companies like Coca-Cola and Pepsi? Soda? Pop? Cola?

What about the athletic shoes made by companies like Nike and Reebok? Sneakers? Trainers? Tennis shoes?

Or, more importantly for aquarists like us, what type of fish was “Dory” in the Disney movie Finding Nemo? If you say Blue Tang, Hippo Tang, Palette Tang, Regal Tang, Flagtail Surgeonfish, or Pacific Blue Surgeonfish, you aren’t wrong.

Just like people from different areas can’t agree on what to call their drinks or shoes, aquarists have lots of different opinions on what to call the fish and invertebrates in our aquariums. These “common names” are just nicknames that we as hobbyists use to identify the animals that we keep. So how do we know that we’re all talking about the same fish when we talk to other hobbyists that might even come from another country or speak another language? Do we pull out a portable DVD player and point to the screen every time?

Enter the Binominal Nomenclature System…the dreaded “scientific names” that we see written in italics in every aquarium guide and identification book we read. No matter what language we speak or what part of the world we are from, every picture of that bright blue fish with the black markings and yellow tail will undoubtedly say the same thing under it….Paracanthus hepatus. Understanding how this system works and how we can use it to our benefit is helpful to every level of aquarist.

A Brief History

This system of classifying and naming every plant and animal discovered started with a family of scientists in the 16th century but didn’t truly begin to gain in popularity and use until a 18th century Swedish botanist by the name of Carolus Linnaeus began to assign a two-part name to every plant, animal or mineral that was discovered. The names were created based on the animals appearance or behavior as they observed it at the time. Even now, some of Linnaeus’s original classifications still stand even though many have been amended as knowledge about the organisms has increased.

One things that hasn’t changed is the Latin Linnaeus used to start his naming system. Latin was already a dead language by the time Linnaeus started using it. No one spoke it in everyday life and only those who were educated in universities had a working knowledge of it. This unpopularity and relative uselessness of the language was what actually made it perfect for scientific use. Using a language that wasn’t used every day means that it won’t change a whole lot. Think back to any classic English works that you might remember like Shakespeare and then think back to a magazine or newspaper that you read last week (or like this blog you’re reading right now, for that matter). Do they sound the same? Language changes and evolves through time but using a language that essentially hasn’t been used since the time of Caesar and the gladiators means that it isn’t going to go through a whole lot more evolving. Latin is also not a national language of any country around the world, then or now, so it is more likely to be accepted by everyone while if the naming system was based on a specific country’s national language, any countries who aren’t too fond of that nation aren’t as likely to use and accept it.

How It Works

 Every creature on Earth is classified into one of 3 Kingdoms – Bacteria, Archaea, and Eukarya (this last Kingdom was adopted in the 1990s to combine four other Kingdoms -Animalia, Plantae, Fungi, and Protista). From there, the classifications are broken down further into a Phylum, Class, Order, Family, Genus and Species. Aquarists and hobbyists primarily use the last of these ranks – Family, Genus, and Species – so that is what we’ll focus on here.

The Family is one of the first ranks where it usually becomes obvious that all the fish in the group are all related. In some of the higher ranks, the similarities may be so vague that it might be hard to tell how two things are related just by looking at them. A Family (usually ending in -ae, by the way) would include all of the fish we commonly know as Tangs or Surgeonfish, for example, although we can still see that a Yellow Tang (Zebrasoma flavescens) is visibly different in body shape from a Hippo Tang (Paracanthurus hepatus). We can tell that if we have a fish with a scalpel-like spine at the base of its tail, a generally teardrop-shaped body, a mouth designed for algae grazing and a flattened body is probably in the Family Acanthuridae with other tangs and Surgeonfish, even if we don’t know yet if it is in the genus Zebrasoma, Acanthurus, Paracanthurus, or Naso.

After the Family, the genus (“genera” in the plural form) is the next level of classification and where we start getting very specific about the identification of an organism as it applied to the aquarium hobby. The genus is the first part of the two-word scientific name. In Rhinecanthus aculeauts, most commonly known as the Picasso Triggerfish, “Rhinecanthus” is the name of the genus which also includes the Bursa Trigger, Huma Huma Trigger, and Rectangle Trigger. At this level, we still can’t point to a fish and know exactly what it is from the genus it is in, but aquarists can typically make some important generalizations about a fish by becoming familiar with the genera commonly available in the aquarium trade. By looking at the genus of a triggerfish, we can usually tell if it is probably going to be a super-aggressive powerhouse (Balistes, Balistoides, Rhinecanthus) or if it will be a more docile, Reef-safe addition (Xanthichthys, Melichthys, Odonus). Genera can lead to some confusion however; as our knowledge of organisms grows, the genus classification is the most likely level to change. This is especially seen in African cichlids. Genera are being added and modified regularly as fish that were once thought of as color variations of the same fish are being classified as new species altogether.

Check back on Wednesday for the conclusion of Eileen’s article.