/The Conscientious Marine Aquarist

Taxonomy: Scientific Classification

Bob Fenner

What makes a Nudibranch so?

Wait! Don't touch that dial! I know what you're thinking. Another wanna be pet-fish ichthyologist taking up precious paper space to try his hand at the world's most boring subject? Nay, nay nay! I promise, this section, will not be only practical and informative, but chock-full (yes, that's how it's spelled) with entertainment value.

Let's take this subject, taxonomy. What!? Another tax? No; you remember, classification. Kingdoms, Orders, Families, Species, blah, blah, blah. What's it to you? Well, if you stick with me, I'll show you how taxonomy will help you thrill, amaze and impress your friends, and (gasp!) make money.

The principal purpose of classification is to take a whole bunch of data: facts, ideas, methods and attitudes, that might seem almost totally unrelated and put them together in a system to make them more useful/useable. How's this work with your livestock? Example: You might know that the Percula clownfish (Amphiprion ocellaris et al.) are sensitive to metal medications and contamination. Knowing that maroons (Premnas biaculeatus) are also members of the same sub-family, Amphiprionae might/would/should lead you have a notion that these species might share similar tolerances, foods, diseases... & so they do! As a matter of fact, should you be so inclined to delve into the literature you'd definitely be impressed with this sub grouping of the damsels. There are about two genera with about twenty nine described species so far. They're all obligate symbionts with certain species of anemones; synchronous hermaphrodites with males becoming larger females with age and need... susceptible to Glugea infections...

Now, isn't easier to just remember that Perc's and sebaes, maroons, tomato clowns, and other related species share family habits and conditions than committing so much ROM (read-only-memory) in your brain for each species separately? Of course! In fact, the related families of fishes in the same Order, the Perciformes (= perch-like fishes), with such notable aquarium species as marine angels and butterflyfishes (Chaetodontidae), the basses (Serranidae), Hawkfishes (Cirrhitidae), and many more

all have structural and useful life-history characteristics in common. And you wondered how anyone could possibly remember so much of this stuff!

And the brain-space savings don't stop here. The "higher taxonomy of fishes involves groups greater than the family level. You will be amazed.

For now, let's get on with a discussion of taxonomy itself. I'll give you a brief historical approach, putting in concepts not generally covered in pet-fish periodicals. Keep in mind the utility of this tool, and enjoy!

Taxonomy or systematics is the science of classifications. There are two divisions: Numerical, which reorders groups along arbitrary lines; such as the Dewey Decimal System; and Biological, which deals with the classification of whole organisms.

It seems that all forms of life on this planet evolved from one, or at most, several common progenitors about three billion years ago. It is, therefore, easy to see why every living thing bears so much in common. According to how much life forms have in common taxonomists place them into more and more definitive groups, e.g. family, genus, species... The study and representation of these relationships is termed phylogeny (Latin for "branch origin") a/the story of life's evolutionary "coming down"...with time organisms radiate in form and function to fill and empty certain ecological niches.

Who's on First?:

Archelaus of Miletus in the sixth century B.C. gets credit by some for coming up with fundamental concepts like species and the sense of need for using one "good" name for each type. But it's Aristotle (384-322 B.C.) with his cadre of graduate students, who generally grasp the credit for the ruminants of scientific classification. Aristotle was aware of the differences between fishes and aquatic mammals (e.g. Cetaceans like dolphins & whales). Many people who followed did not know this. He accurately described some 118 species of fishes from the Aegean Sea, but had little idea of the mutability of local names, or evolution.

A few others, who came later in the "ancient" world made further recordings of what they recounted as types of organisms. Pliny, Aelianus, Authinecus... In the sixteenth and seventeenth centuries Belom (1518-64, Rondelet (1507-57, Salviani (1513-72) and Ray and Willoghby (publ. 1686) were noted chroniclers of fish-naming.

The real "birth" of modern taxonomy has it's point of origin the tenth edition of Systema Naturae, (1758) by Carolus Linnaeus (Karl von Linne), the "father" of modern taxonomy. Linnaeus gets the big credit for innovations like the "two-word naming" (binomial nomenclature) of species and arrangement of categories like classes, orders, and families (taxa, singular taxon).

What this all means is that, when you're out and about, collecting fishes and trying to determine whether you've got a new species or not, you've got to go back all the way to the year

1758 and search the pertinent literature to determine whether or not you've found something new.

Similarly, around the world, folks who study structure, biochemistry, genetics, behavior et al. are trying to make sense of higher/greater similarities of these organisms and grouping these assemblages into larger and smaller genera, families, orders... You start to see that this is a very human, read that artificial enterprise. One subject to change with new and better data.

The fishes themselves don't arrange themselves in the "families" we put them into; and the folks in Natural History Museums, Zoos, Aquaria, learning institutions and private investigators who do the studies and the lumping/splitting are mere mortals like us. These classifications are mere useful fabrications for ranking and ordering related information. With perhaps as many as forty thousand valid species to be counted, scientific classification goes a long way to, on the one hand, work-out the phylogenetic relationships of organisms and their implications, and on the other hand, keep track of all the disparate information about our fishes. For real spiffy specifics on the minutiae of naming check out Leibel and Ford's pieces cited below.

Further Reading & Where I Lifted This Stuff:

Ford, David. 1981. Understanding Basic Aquarium Science & Calculations. Freshwater & Marine Aquarium (FAMA) 4(5)

Leibel, Wayne S. 1985. Of Pickled Fish & Ichthyological Sleuthing: A Primer for the Advanced Aquarist Part 1: The Whys and

Wherefores of Scientific Nomenclature. FAMA January Issue

Nelson, Joseph S. 1976.Fishes of the World. John Wiley & Sons.

Sterba, Gunther. 1966. Freshwater Fishes of the World. The Pet Library Ltd. English Translation

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