Activity: Taxonomy

  1. Notice that each bivalve species has three parts to its name. Consider the name Mercenaria mercenaria (Linnaeus, 1758):
    1. The first word (Mercenaria) is the genus name — it is always capitalized and italicized.
    2. The second word (mercenaria) is the species name — it is always italicized and in lower case. If the species is unknown, the species name is replaced by “sp.” (not italicized).
    3. The third part to the name is the taxonomic authority — a name and date (Linnaeus, 1758) of the person or persons who first described the species. Parentheses are present around the name and date if the species is now placed in a genus different from that originally used (in our example, Mercenaria mercenaria was originally described in the genus Venus). The taxonomic authority is often omitted in sentences, but it is important in scientific contexts because very common species names, such as albus = white, or variabilis = variable, have been used more than once, often in the same genus.

      A note about Common Names: In your classroom discussions, encourage your students to use the scientific names of the bivalves. Although common (non-scientific) names are often provided, and in general are easier for non-scientists to understand, they are not universal and are often misleading. This is especially true for invertebrates like bivalves; it is less of a problem for birds and mammals, which have had standardized common names for many, many years. So, whereas the name Black-Capped Chickadee can only mean one species of bird [Poecile atricapillus (Linnaeus, 1766)], the bivalve Mercenaria mercenaria (Linnaeus, 1758) is known variously as Hard-shelled Clam, Hard Clam, Northern Quahog, Cherrystone, Little-neck Clam, or Steamer Clam, depending on who is speaking and where they are from. This is further complicated by the fact that “Steamer” can also refer to Mya arenaria (Linnaeus, 1758), and “Quahog” to Arctica islandica Linnaeus, 1767. A similar case can be made about the word “mussel” — applied to marine mussels, freshwater mussels, and the invasive Zebra Mussels (each in a different family and genus).

      Common names are especially important to the field of environmental conservation, in which scientists must communicate effectively with governmental officials, who are often not scientists. If two groups of scientists call an endangered bivalve by two different common names, legislators will think either more than one species of bivalve is being discussed, or the scientists do not know what they are talking about. The American Fisheries Society has supported efforts, including publication of a checklist, to standardize names of American species of bivalves [1].

  2. Ask your students to do some research on the taxonomic authorities of bivalve species. Notice the varied professions that these people held (professor, geologist, museum curator, “naturalist”).

    For example, many bivalve species are credited to “Linnaeus, 1758.” This is the earliest date that you will ever see as a taxonomic authority, because taxonomists have designated this work — Systema Naturae, 10th edition (1758), by the Swedish naturalist Carolus Linnaeus (also known as Carl von Linné) — as the beginning of modern taxonomy. Linnaeus invented binomial nomenclature, which replaced long, wordy descriptions and provided a universally recognized name for each species. Because he was the first, Linnaeus is credited with the names of many of the most common bivalves, and in fact, many of the most common animals, including:

    • Hard-shelled Clam, Mercenaria mercenaria (Linnaeus, 1758)
    • King Scallop, Pecten maximus (Linnaeus, 1758)
    • Blue Mussel, Mytilus edulis Linnaeus, 1758
    • Green Sea Turtle, Chelonia mydas (Linnaeus, 1758)
    • White Shark, Carcharodon carcharias (Linnaeus, 1758)
    • Crow, Corvus corone Linnaeus, 1758
    • Gray Wolf, Canis lupus Linnaeus, 1758
    • Human, Homo sapiens Linnaeus, 1758

    Here is a list of other authors that your students might research. What species did they name?

    • Thomas Say
    • William Healy Dall
    • Johann Friedrich Gmelin
    • Michael Tuomey & Francis S. Holmes
    • Peter Simon Pallas
    • Jean Guillaume Bruguière
    • Angelo Heilprin

  3. The scientific names of organisms have meaning, often describing characteristics of the species. Ask your students to look up a scientific name of one of these bivalves in a Latin dictionary and compare that to the shell.

    • For example, edulis means “edible,” and maximus means “large.” So, Mytilus edulis is the “edible mussel,” and Pecten maximus is the “large scallop.”
    • Some species are named after people or places. So, Chesapecten jeffersonius is “Jefferson’s Chesapeake Scallop” and Crassostrea virginica is the “Virginia Oyster.”
  4. New species of bivalves are being described every year, if not every month or week. Ask your students to research new species recently described. Where have they been described from? What kinds of data (morphology, molecules, ecological traits) have been used to characterize the new species? Think about why these species have never been described until now.
  5. Create some new bivalve “species” out of paper and ask your students to name them, explain the meaning of each name, and list the key morphological features of each one.

See also the Activity Finding Nature’s Order: Classification.


  1. Turgeon, D. D., J. F. Quinn, Jr., A. E. Bogan, E. V. Coan, F. G. Hochberg, W. G. Lyons, P. M. Mikkelsen, R. J. Neves, C. F. E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. G. Thompson, M. Vecchione, and J. D. Williams. 1998. Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks, 2nd ed. American Fisheries Society, Special Publication 26, Bethesda, Maryland, 526 pp. + CD-ROM.