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Introduction to Taxonomy

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What is taxonomy?

The countless living organisms on Earth are divided into categories based on their evolutionary ancestry, common characteristics, and shared genetics. The science of classifying organisms is called taxonomy. The first modern taxonomic system was developed by Carl Linnaeus. His system, which was published in the work Systema Naturae in 1758, contained eight levels of division that could be used to categorize any organism and is still used today. These levels of division begin with the broadest category (Domain) and end with the narrowest (species).


Domain

Broadest division, contains the greatest number of organisms

Kingdom


Phylum


Class


Order


Family


Genus


Species

Narrowest division, contains the smallest number of organisms


At the domain level, there are three categories into which organisms can be divided: Eukarya, Archaebacteria, and Eubacteria. The six kingdoms are Archaebacteria (in the domain Archaebacteria), Eubacteria (in the domain Eubacteria), Plantae, Animalia, Protista, and Fungi. Most of the organisms observed in underwater video footage are in the Domain Eukarya and the kingdom Animalia, and they have fallen into approximately ten phyla thus far: Porifera, Cnidaria, Echinodermata, Arthropoda, Chordata, Annelida, Mollusca, Ctenophora, and Bryozoa. In the benthic marine environment, most of the observed animals are members of Porifera, Cnidaria, and Echinodermata. Starting with the class division, there are over twenty different categories, with each becoming increasingly specific until a single species designation is left. On the following page are two animals with their scientific classifications.

A groundhog eating grass in a lush green setting.
Figure 1. Marmota monax
Red, spiky fish with a frown sits on dark rocks underwater. I
Figure 1. Chaunacops coloratus

Groundhog Domain: Eukarya

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Rodentia

Family: Sciuridae

Genus: Marmota

Species: Marmota monax

Anglerfish Domain: Eukarya

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Order: Lophiiformes

Family: Chaunacidae

Genus: Chaunacops

Species: Chaunacops coloratus


These two animals are of the same domain, kingdom, and phylum. The first difference in their taxonomy is found at the class level. Organisms that are in the same group at a lower taxonomic level are more closely related.


Naming System

Organisms are named using binomial nomenclature, a two-part naming system with a genus name and species epithet. There are several rules that must be followed when giving the scientific name of an organism.

  1. The genus name is written first. Ex: Chaunacops.

  2. The species epithet is written second. Ex: Chaunacops coloratus.

  3. The genus name is capitalized, while the species name is not. Ex: Chaunacops coloratus.

  4. The genus and species names are both italicized. Ex: Chaunacops coloratus.

  5. If the scientific name is used multiple times in a document, the entire name must be used first. Subsequently, the genus name may be shortened to the first letter and a period, unless it is placed at the beginning of a sentence. Ex: Chaunacops coloratus (first mention); C. coloratus (subsequent mentions). 

Organisms present in video footage cannot always be identified to the species level. They can be classified by their class, order, family, or genus instead. However, because the use of a genus name by itself refers to all species included within that genus, the genus name is followed by “sp.,” an abbreviation for species, to designate an organism that could only be identified to the genus level. Similarly, “cf.” and “nr.” can be used between the genus and species names to demonstrate a degree of uncertainty with regards to the species name.


Activity 1: Taxonomic Key

Use the WoRMS (http://www.marinespecies.org/index.php) and MBARI (http://dsg.mbari.org/dsg/home) databases to make a Google Sheets spreadsheet with the major taxonomic classifications (kingdom, phylum, class, order, family, genus, species) for each assigned animal. 


  1. Open the “Taxonomy Lab Images” Google Drive Folder. Observe the select images of the assigned individuals. 

  2. Open the WoRMS (http://www.marinespecies.org/index.php) or MBARI (http://dsg.mbari.org/dsg/home) search platforms. Type the scientific name into the search bar. Select the entry for the individual and observe the taxonomic classification. 

    1. Delete the “sp.”, “cf.”, or “nr.” from the Scientific Name before searching the individual if present. 

    2. When entering the scientific name in WORMS, the given name may be followed by a last name and year, indicating the scientist who initially described the animal.

Figure 3. WoRMS taxonomy website
Figure 3. WoRMS taxonomy website

  1. Make a copy of the Google Sheet  “Taxonomic Key Template.” Within each row, fill in the taxonomy for the individual, using only the taxonomic classifications in the template. For instance, in the entry for Coryphaenoides longicirrhus, only enter the kingdom, phylum, class, order, family, subfamily, genus, and species. 

Figure 4. Detail of taxonomy from WoRMS website.
Figure 4. Detail of taxonomy from WoRMS website.
Figure 5. Detail of taxonomy from MBARI Deep-Sea Guide.
Figure 5. Detail of taxonomy from MBARI Deep-Sea Guide.

  1. Only list the taxonomy to the rank denoted in the image title. If an individual is not classified to the species level, put two hyphens (--) in the data entry box for each box within the row beyond the given classification.

  2. Continue to fill out the template for each assigned individual. 

    1. An example of the template can be found here.

You will upload your spreadsheet to the learning management system your institution uses and/or provide a printout to your instructor.


Activity 2: Taxonomy Tree

Make your own taxonomy tree!  Research different animals using the links listed below.  Choose one animal that interests you that is identified down to at least the genus level.  Use the WoRMS guide (link in (e.) below) to investigate that organism’s taxonomy.  Then, design a tree with taxonomic identification as is displayed in Figure 5 above.  Include a picture of the organism with its taxonomic information.  Write a short 300-350 word summary of what we know about the organism (or group that the organism belongs to).  You will turn the document in to your instructor and/or upload it to the learning management system your institution uses.


Research links

  1. NOAA’s Benthic Deepwater Animal Identification Guide V3: can search by phylum and class/family; has images.

  2. MBARI’s Deep-Sea Guide: can search by name. 

  3. HURL’s Animal Guide: can search by name or by phylum. 

  4. Project MINUET’s Animal ID Guide: can search by any classification level; has images.

  5. WoRMS (World Register of Marine Species): can search by any classification level.

  6. For more guidance in identifying and distinguishing between organisms, reference this guide.











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