Snails, highly valued by teachers, are blacklisted
The long arm of the federal law has reached out to Denise Geistfeld's kindergarten class at Franklin Elementary School in Mankato.
Every spring for eight years, Geistfeld has led her class through a unit on scientific observation that, for two weeks, focused on a common land snail called Helix aspersa. The kindergartners watched how the marshmallow-sized snails moved and ate, raced them against one another, compared them to pond snails and recorded observations in a snail journal.
The snails are "a fabulous, fabulous thing — they're the meat of the unit," says Geistfeld. Other teachers apparently agree: The University of California at Berkeley and the Smithsonian Institution, the developers of two science curricula that use snails, estimate their lesson plans are used in about a third of the nation's 17,000 school districts.
But last summer, the U.S. Agriculture Department banned the interstate transport of Helix aspersa, throwing school science into disarray and setting off a last-minute search for a substitute that has at least as much personality as the snail. So far, the news isn't good.
As teachers tell it, the land snail is an ideal creature for small children to study. It's squish-resistant, large enough that children can easily see its eyes and breathing tube, and active enough, in its own way, to keep them engaged. It's translucent: Whatever it eats can be seen passing into its digestive tract. A light shone on its shell reveals its beating heart. And it defecates in color: orange after eating a carrot, green after spinach, and pink after the Tums tablets it is fed to keep its shell hard.
"Snails will do something meaningful in a 50-minute class period," says Teri Dannenberg, a Berkeley curriculum developer.
Berkeley's curriculum writers began including snails in lesson plans about 15 years ago. Third graders see how many paper clips snails can pull (typically, the equivalent of 10 times their weight), and middle schoolers study how snails adapt to their environment.
The snails were "a very cool unit," says Mary Harris, whose third-graders at Oak Ridge Elementary School in Eagan, Minn., studied snails last spring using the Berkeley lesson plans: "Those little creatures have such a personality."
Environmentalists and farmers, however, aren't so enchanted.
French immigrants apparently introduced Helix aspersa to California in the 1800s. The ravenous, fast-breeding organism took hold, infesting the state's citrus crop and threatening its nursery plant industry. The snail is now "a major pest beyond the hope of eradication," says Steven Lyle of the California Agriculture Department. As it inches east, state agriculture departments everywhere are wary.
David Hanken, a USDA permit specialist, says he doesn't know how the snails are getting into other states, but he suspects one reason is that teachers are turning them loose. Suppliers tell teachers to destroy them by tossing them into a freezer, but "some teachers have issues with killing things," Hanken says.
Because only the interstate transport of snails is banned, schools that find their own can still study them. Marcie Snowden asked her kindergartners at Summit Charter School in Cashiers, N.C., to bring snails from home. "I have no clue what kind they are," she says, but they're the same snails she kills during her summer job as a landscaper.
Most districts need hundreds of snails, though, and aren't located in Helix aspersa territory. Berkeley at first advised teachers to show their kindergartners a video about snails. That's what Geistfeld in Mankato plans to use. "It will be fine," she says, with an air of resignation.
But a video defeats the purpose of the curriculum, which is to provide hands-on science lessons. So Dannenberg, the curriculum writer, suggested that teachers ask their suppliers for Madagascar hissing cockroaches, Bess beetles or slugs.
But school districts "won't allow anything called a cockroach," Dannenberg says. The Bess beetle is nocturnal and has no aquatic equivalent. "They're not as dynamic" as a snail, she insists. A slug, aside from its considerable aesthetic issues, "is hard to entice" to move, she adds, and besides, "they don't poop pink."
Meanwhile, the USDA's Hanken also is searching for alternatives and has posted a Mollusk Decision Matrix on the department's Web site. The matrix lists seven snails and the states where each is common enough that the USDA may allow suppliers to ship in still more for classroom use. So far, Mesodon thyroidus, or the whitelip globe snail, seems acceptable in 31 states, and Hanken has shipped a colony to Dannenberg for curriculum trials.
But unlike Helix aspersa, there's no infestation of Mesodon thyroidus anywhere, and thus no ready supply. It could take years for suppliers to collect and breed all the snails that the classrooms need, says Hanken.
"We have the snail candidates; now we have to find people to supply them to us," says Dannenberg, urging teachers to hold on. She promises news by this fall.