Taxonomy of the Animal Kingdom: The ICZN Code (Part III)

We've come a long way in understanding how zoological nomenclature works. Understanding it is one thing, and appreciating it is another. Today we look at the ICZN Code, the one that started it all.

One More To Go.....

Hiya everyone! This is the final part of our three-part series on the taxonomy of the animal kingdom. It's been a long one, and I hope that everyone's been enjoying the (albeit lengthy) explanations on how it works! Fret not, we're already at the end.

This final part simply discusses a little on the ICZN Code. The rest will be a complete summary, as well as a lil' pop quiz for y'all to try. Make me proud!

The ICZN Code

Alright alright. I've been throwing this term around so many times already, it's getting annoying. What is the ICZN? In short, it is the International Code of Zoological Nomenclature. Not to be confused by its publisher, the International Commission on Zoological Nomenclature. (Also ICZN!)

The code is a generally accepted criteria/ruleset that governs and regulates a few things:

- How names are established with utmost accuracy under the concept of binomial nomenclature.

- How names must be manipulated in the case of conflicts (where names clash).

- How scientific literature must cite names.

Basically, the ICZN Code ensures that in the naming of all known animals, continuity and universality are key retaining factors. This ensures that there is no doubt or conflict when naming animals, and that it should generally be understood anywhere in the world.

Do focus on the word naming here. The code only regulates and enforces the raw naming of an entity, but does not suggest whether an identified entity should or should not be recognized as an animal/organism.

Fundamental Principles of the ICZN Code

The ICZN Code retains several principles to ensure the fairness and universality of everyone who works with the code. There are six of them as of today:

*In accordance to keeping it short, each principle will only be briefly discussed on.

The Principle of Binomial Nomenclature

- This principle states that the scientific name of a taxon under the rank "species" must be named in accord to the rule of binomial nomenclature/two parts.

- The name of a species must be of 2 parts, a generic name and a specific name.

- In the case of a subspecies, the name of a subspecies must be of 3 parts, a trinomen: A generic name, a specific name and a subspecific name.

The Principle of Priority

- This principle states plainly that the correct scientific name given to a taxon is the oldest (established earlier) known and available name given to it.

- You can see how this is priority, as (obviously) priority is given to of course, the earliest available name applied.

The Principle of Coordination

- This principle states that when a name is established for a taxon of any rank, that assigned name will be established together with the person and date at which he/she established that name.

- Alongside that, this will be the same for all ranks within that assigned taxon's group.

- Sound a bit confusing? To put it in an example: Carl Linnaeus, a zoologist, discovered the species Giraffa camelopardalis in 1758. This makes it in full: Giraffa camelopardalis Linnaeus, 1758. As well as that, the genus name for this species also makes it Giraffa Linnaeus, 1758. This goes on and on for all taxa under this group.

The Principle of the First Reviser

- Remember the principle of priority? Well, if in any case it cannot be applied to a name conflict, the first person who settles and solves the conflict becomes the first reviser.

- The first reviser will then have priority to decide what is the correct solution to deciding the name during a conflict in naming.

- Example: Linnaeus establish 2 species: Strix scandiaca and Strix noctua. He gave them both different descriptions. Later on, this turned out to be false because they were actually the same species. The first reviser who corrected this then got to decide whether it would be named Strix scandiaca or Strix noctua. He later decided it to be Strix scandiaca.

The Principle of Homonymy

- To put it simply, this principle states that each taxon name must be unique, and cannot be used more than once.

- Likewise, the principles of priority and the first reviser apply here, to ensure fairness!

The Principle of Typification

- Without going into detail, this principle embodies the type-genus and type-species concept, that any named taxon must have a name-bearing type to it, that can act as a reference when naming taxon in the same group.

And there we have it! Quite simple isn't it? I didn't go into too much detail, as it was simply too much. Now, we'll do a recap on binomial nomenclature and end with a fun quiz!

The ABCs of Zoological Nomenclature

A step-by-step guide to understanding how the nomenclature system works!

Part 1: The 8 Principle Taxonomic Ranks

Easy as it goes! Starting from the most general category, with each category getting more specific as it goes down:

- Domain

- Kingdom

- Phylum

- Class

- Order

- Family

- Genus

- Species

Part 2: Nomenclature Guidelines

There are 4 categories of importance in the guidelines set for zoological nomenclature:

A: Names above the family group (Not strict)

B: Family-group names (Type genus concept + Suffixes)

C: Genus-group names (Type species concept)

D: Species-group names (Binomial nomenclature + Trinomial nomenclature)

Each category involves different concepts and rules when deciding on a name.

A. Names above the family group

- This involves all taxonomic ranks above the rank of family.

- There is not much in terms of restrictions when it comes to assigning a name for any of the ranks.

B. Family-group names

- Not strictly speaking, under the rank of family also exists a multitude of sub-ranks. For each of these sub-ranks, they have to adhere to a fixed suffix set for each of them. In order from general to more specific, followed by their respective suffix:

- Superfamily: -oidea

- Epifamily: -oidae

- Family: -idae

- Subfamily: -inae

- Infrafamily: -odd

- Tribe: -ini

- Subtribe: -ina

- Infratribe: -ad or -iti

C. Genus-group names

- A genus-group name only comes in one part/name. It is defined by it's type species.

- The type species of a genus is the defining species which represents and acts as the root name of all other species within its own genus. An example is:

Type Species: V. vulpes

- V. vulpes is the scientific name for the red fox. As it is the type species for its genus, the genus will be called Vulpes!

- A comparison would be the arctic fox, V. lagopus. It is not the type species for its genus, so the genus is not called Lagopus. It however, is still under the same genus as V. vulpes.

D. Species-group names

- A species names comes in 2 parts, whereas a subspecies (more specific) comes in 3 parts. The general structure for naming each is pretty simple:

Species (Binomial) Name: Generic name + Specific name

- And by substituting the generic/genus and specific name for that taxon:

Example (Genus Vulpes): Vulpes + Vulpes = Vulpes vulpes

As for the subspecific name:

Subspecies (Trinomial) Name: Generic name + Specific name + Subspecific name

By substitution again, we take an example from the Sunda Island tiger:

Example (Genus Panthera): Panthera + Tigris + Sondaica = Panthera tigris sondaica

With this in mind, let's jump into the quiz!

Quiz Time!

This quiz consists of 3 simple questions, each testing how well you know your ABCs. No pressure, just do it to test yourself... for fun! The answers for each will be listed at the very bottom :P

Question 1. Subspecies Breakdown

Subspecies in question: Rhinoceros sondaicus annamiticus, the Javan rhinoceros.

- State the subspecific and specific name, as well as the genus that this animal falls under.

Question 2. Type Species Identification

Scenario: There are 5 species under the genus Panthera. Which is most likely to be the type species for the genus Panthera? Select one.

- Panthera tigris

- Panthera uncia

- Panthera onca

- Panthera pardus

- Panthera leo

Question 3. Taxonomic Rank Structure

Scenario: Drosophila melanogaster, the common fruit fly, is the type species of the sub-genus Sophophora. Based on the options given for each taxonomic rank, identify the following: (Pick one for each category)

A. Genus of D. melanogaster

- Sophophora

- Dorsilopha

- Drosophila

B. Family of D. melanogaster

- Drosophiloidae

- Drosophilidae

- Drosophilinae

C. Subfamily of D. melanogaster

- Drosophilina

- Drosophilini

- Drosophilinae

D. Order of D. melanogaster

- Procolophonomorpha (Parareptiles)

- Lepidoptera (Insects)

- Diptera (True flies)

E. Class of D. melanogaster

- Aves (Birds)

- Diplopoda (Arthropods with 2 pairs of jointed legs)

- Insecta (Insects)

F. Phylum of D. melanogaster

- Arthropoda (Arthropods)

- Tardigrada (Water bears)

G. Kingdom of D. melanogaster

- You should know this by now.... :D


(Psst, don't let me down! Get 'em all right!)

1. Subspecies Breakdown

- Subspecific name: Annamiticus

- Specific name: Sondaicus

- Genus: Rhinoceros

2. Type Species Identification

- Panthera pardus

3. Taxonomic Rank Structure

A: Drosophila

B: Drosophilidae

C: Drosophilinae

D: Diptera

E: Insecta

F: Arthropoda

G: Animalia (Kingdom Animalia, remember?)

And There We Have It...…

Here is a cute GIF for you to destress... because why not :,)

And yes, there we have it! We've reached the end of this series on the taxonomy of the Animal Kingdom. I've said this countless times before, but I really hope that each and every one of you, no matter how little, have understood the basics on how to name an animal (scientifically :P).

By understanding, it's amazing how the little things that you see in your everyday life can change. After extensively understanding how the nomenclature works, even on a surface level, every time I see a pet in my friends' and family's homes, I often wonder what their scientific name is, and what rank they fall under. Every little bit of extra knowledge goes a long way, and it's satisfying when you know you can apply it to your everyday life, even if its insignificant :)

Until next time.... adios!