Q. Dear Twig: How many kinds of clams are there?
A. Well, "clam," in general, means a bivalve mollusk. That's a mollusk with a two-part shell. If you lump all the bivalve mollusks on Earth all together — the clams, mussels, oysters and scallops — they add up to about 15,000 species.
In Ohio, my home, the clams/mussels go by such weirdly excellent common names (as opposed to their weird, less-excellent, but-more-accurate scientific names) as fluter, creeper, peewee ("That's my name! Don't wear it out!"), sheepnose, blue ham, pancake, hogshell, ring pink, pink pigtoe (ree!), Ohio pigtoe (ree, ree!), snuffbox, slopbucket, fatmucket, heelsplitter (ooch!), monkeyface (oop!), strange floater, purple wartyback and orange-foot pimpleback.
I tip my cap to this bivalve biodiversity! But also I see that it needs our help. Some 70 percent of America's freshwater mussels are declining, endangered or extinct. Which stinks. I give that a blue-ham salute.
P.S. Dive into OSU clam info! http://www.biosci.ohio-state.edu/~molluscs/OSUM2/index.htm.
Notes: The Web site is by the Division of Molluscs, Museum of Biological Diversity, part of Ohio State's Department of Evolution, Ecology and Organismal Biology. Sources also included the U.S. Fish and Wildlife Service, http://www.fws.gov/news/mussels.html; the University of Vermont ("Fun With Freshwater Mussels"), http://www.uvm.edu/%7epass/tignor/mussels/; the Freshwater Mollusk Conservation Society, http://ellipse.inhs.uiuc.edu/FMCS/; and Field Guide to Freshwater Mussels of the Midwest by the Illinois Natural History Survey, http://www.inhs.uiuc.edu/cbd/collections/mollusk/fieldguide.html. FYI: "Mollusk" is sometimes spelled "mollusc," especially in England.
"Smart Stuff with Twig Walkingstick," published by The Ohio State University College of Food, Agricultural, and Environmental Sciences — specifically, by the Ohio Agricultural Research and Development Center (OARDC) and Ohio State University Extension, the research and outreach arms, respectively, of the College — is a weekly column for children about science, nature, farming and the environment. It's written at a 4th-grade reading level. For details, to ask Twig a question, and/or to receive the column free by mail or e-mail, contact Kurt Knebusch, CommTech, OSU/OARDC,1680 Madison Ave., Wooster, OH 44691, email@example.com, (330) 263-3776. Online at http://extension.osu.edu/~news/archive.php?series=science.