Beans don't jump – do they?

During evenings after work in late summer, Tom Kramer can usually be found in an upstairs room of his home in northwest Houston. There his two cats – Shadow and Chloe – drop by from time to time to help him count his beans.

Mr. Kramer's beans, however, are not the edible type. They aren't the baked or green variety, either. Nor are they coffee beans or jelly beans.

In fact, Kramer's beans aren't really beans at all.

During a winter business trip to Mexico six years ago, "memories of Mexican jumping beans came to mind," he says. "So I decided to find some of these little marvels of nature for my kids as a gift."

He spent an unsuccessful day looking through various shops. But he eventually found an elderly shopkeeper who informed him that jumping beans were available only in late summer. Disappointed, he returned to his family in Houston, beanless.

"But I couldn't quit talking about the 'magic' beans that jumped," Kramer admits. His family hadn't heard of them before. "The kids thought I was nuts!"

Fortunately, Kramer's wife visited San Antonio a little later and found some jumping beans in a local store. "He was able to save face with the kids by proving that Mexican jumping beans really did exist, and that he was not crazy," she says.

So what, exactly, are Mexican jumping beans?

Just as the peanut is not really a nut, and the pineapple is not an apple, jumping beans are not true beans. They are actually the seedpods of a desert bush with the scientific name of Sebastiana pavoniana. It grows in the Mexican states of Sonora and Chihuahua.

"It's a small shrub with shiny green leaves," says Tom Van Devender, a research scientist at the Arizona-Sonora Desert Museum in Tucson. "Its Mexican name is brincador, meaning 'jumper,' in reference to the insects within the seeds that cause them to move erratically about."

Each spring, female moths deposit their eggs on the shrub's flowers. When the tiny insect larvae hatch, they burrow into the young flower capsules. There they chomp away inside the developing seed, leaving the undamaged seed wall – the "bean" – as their protective fortress.

Once the invading caterpillar has carved out some living space, it begins to construct a web inside the seed. Before long, each "bean" comes to life, as the yellowish-white larva uses the web to fling itself against the walls of its chamber, producing erratic jumping movements.

Exactly why the larvae do this is a bit of a mystery to scientists. Possibly they are trying to move the seedpod into the shade to avoid being roasted in the hot desert sun.

It is an exaggeration to say that the beans actually "jump." They really scoot, roll, or tumble just a tiny bitevery so often. But even that was enough to impress the Kramer kids and their friends when they first saw them.

And that gave Mr. Kramer an idea. He recognized there was a new generation of kids who had never experienced these curiosities of nature. So he created an Internet site, www.beansthatjump.com, which offers the beans and tells all about them.

This is the place to discover that you shouldn't shake or drop your jumping beans, but you should give them a "drink" of water each week.

The beans typically remain active for three to five months.

Jumping-bean production is affected by weather conditions in Mexico, such as drought, and some years the harvests are poor.

"But this should be a good year," says Kramer.

While he does most of the work of marketing, packaging, and shipping the beans himself, he does have some part-time assistants: the family cats.

They have always displayed a feline fascination for the brownish-colored beans, especially when they mysteriously rattle in their plastic cases while they're awaiting shipment.

So Kramer put the curious kitties to work.

If a bean shows no signs of activity, it may not be alive. So he sets aside these possible duds for Shadow and Chloe to "inspect."

If any of these beans show signs of movement, the watchful cats begin playing with them and Kramer returns those beans to the live bin.

"The best part of this labor pool," he says with a big grin, "is that I don't have to pay them!"

Jumping beans have been available in the United States since the 1940s, when some say that a 12-year-old boy in Alamos, Mexico, got the idea to start selling them in novelty shops.

Today, local collectors in Mexico sell the "beans" for about $20 per thousand beans.

In a good year, more then 20 million jumping beans are exported from Mexico.

Each bean has a small, almost perfectly circular "door" that the emerging moth pushes open.

The sap of the jumping bean shrub is poisonous and is said to have been used in the past by some Indian tribes to make poisoned arrows for hunting.

Jumping beans are currently orbiting the Earth aboard Genesis I, a private space vehicle launched in July by Bigelow Aerospace. A picture of the beans in space can be seen at www.bigelowaerospace.com/out_there/view_photos.php.

To see video clips of jumping beans in action, ask a parent or teacher to access www.youtube.com and do a search for "jumping beans." (Not everything that comes up in the search may be about real jumping beans.) It's fun to watch them jump!