When it comes to research on venom and converting it into useful drugs, studies involving exotic snakes or brightly colored frogs seem to attract the most attention. However, one of the most promising new venom-derived drugs actually comes from a very modest-looking sea snail.

Worldwide, there are more than 600 kinds of cone shells found mostly in tropical waters around the Pacific. Collectors love them because their shells are decorated with an amazing array of intricate patterns.

Biologists, however, have long been fascinated by the behavior of these clever hunters. Some cone shells target other snails, while others like to feast on fish. To sense food, cone shells filter water through a tubelike organ called a siphon, awaiting a whiff of the telltale chemicals emitted by their prey.

To sense food, cone shells filter water through a tubelike organ called a siphon.

Then, when its victim comes near, the cone shell extends a proboscis armed with a harpoonlike tip that injects venom filled with special chemicals called “conotoxins.” These toxins stop nerve cells from communicating with each other, causing paralysis within seconds and, eventually, death. Cone shells have even killed people who pick them up, unaware of the danger. Indeed, cone snail venom is so powerful and painless that victims can die unaware that they’ve even been bitten.

Conotoxins have long interested medical researchers because of their potential painkilling abilities. It turns out, however, that cone shell venom is very complex; each kind contains perhaps 50 or more different chemicals that target the brain and nervous system. Overall, researchers believe that more than 50,000 conotoxins may exist. That diversity has made it hard for them to isolate a specific chemical to work on.

But over the last few decades, conotoxins have begun to give up their secrets. Researchers have published more than 2,500 papers on the chemicals, and have described and identified more than 100 specific toxins which show promise for treating everything from arthritis to cancer. But the first new drug derived from a conotoxin, approved in 2004, targets chronic pain. Researchers estimate that the drug, based on the venom from the delicate gray and ivory magician cone shell, is a thousand times stronger than morphine, the most powerful traditional painkiller.

Even as cone shells show promise for medicine, however, their survival may be at stake. Collectors gather millions of the animals each year for the decorative shell trade. Demand from conotoxin researchers is growing too, since many shells may be needed to produce even small amounts of toxin. And coral reefs, which support more than half of all cone shell species, are under increasing threat from human activities.

To protect cone shells, biologists are asking nations in tropical zones to take new steps to monitor the shell trade and protect reefs. “To lose these species would be a self-destructive act of unparalleled folly,” researcher Eric Chivian of Harvard University in Cambridge, Massachusetts wrote in a 2003 paper published by the journal SCIENCE. “Tropical cone snails may contain the largest and most clinically important pharmacopoeia of any [group of animals] in nature.”

Producer: Ronnie Godeanu
Art Director: Sabina Daley
Graphic Art: Lenny Drozner
Writer: David Malakoff
Technical Director: Brian Patrick Lee
Scientific Consultant: Gianna Savoie

Thirteen Online is a production of Thirteen/WNET New York’s Kravis Multimedia Education Center in New York City. Anthony Chapman, Director of Interactive & Broadband. Carmen DiRienzo, Vice President and Managing Director, Corporate Affairs.

© 1998 Thirteen/WNET New York

All Rights Reserved

Television Credits

A Co-Production of Thirteen/WNET New York and BBC-TV

Funder Credits

Funding for the TV series NATURE is made possible in part by Park Foundation. Major corporate support is provided by Canon U.S.A., Inc., Ford Motor Company, and TIAA-CREF. Additional support is provided by the nation’s public television stations.

For those interested in the subjects shown on SECRET GARDEN, we present the following Web sites. All links are valid as of December 21, 2000.

Biggs Wildlife Pond
http://www.sonic.net/~bigsnest/Pond/
Learn about the pond that Kathy and Dave Biggs created in their backyard and see pictures of the plants and animals it supports.

The Butterfly Zone
http://www.butterflies.com/
Tips on how to start your own butterfly garden, with links to a butterfly identification guide and the story of one man’s garden.

The Backyard Wildlife Habitat Program
http://www.nwf.org/backyardwildlifehabitat/
The National Wildlife Federation provides a wide array of resources for creating backyard habitats and understanding the plants and animals that live in them.

Smithsonian Butterfly Habitat Garden Homepage
http://www.si.edu/gardens/butterfly/
Extensive site detailing butterfly garden do’s and don’ts, as well as fascinating insights into the natural history of butterflies and plants.

Seed Savers Exchange
http://www.seedsavers.org/Home.asp
Web site of the organization that protects heirloom seeds, which can also be reached at the following address: Seed Savers Exchange, 3076 North Winn Road, Decorah, IA 52101.

Green Landscaping With Native Plants
http://www.epa.gov/greenacres/
Extensive site with practical advice from the U.S. Environmental Protection Agency.

Print Resources

For those interested in the secret life of the garden and gardening, we recommend the following books.

Bodanis, David. THE SECRET GARDEN: DAWN TO DUSK IN THE ASTONISHING HIDDEN WORLD OF THE GARDEN. New York: Simon & Schuster, 1992.

Capon, Brian. BOTANY FOR GARDENERS: AN INTRODUCTION AND GUIDE. Portland, Oregon: Timber Press, 1992.

Conrad, Jim. DISCOVER NATURE IN THE GARDEN: THINGS TO KNOW AND THINGS TO DO. New York: Stackpole Books, 1996.

Daniels, Stevie. THE WILD LAWN HANDBOOK. New York: Macmillan Publishing Co., 1995.

Druse, Ken, and Margaret Roach. THE NATURAL HABITAT GARDEN. New York: Crown Publishing Group, 1994.

Kress, Stephen W. THE BIRD GARDEN. London: Dorling Kindersley, 1995

Rogers, Marc, and Polly Alexander. SAVING SEEDS: THE GARDENER’S GUIDE TO GROWING AND STORING VEGETABLE AND FLOWER SEEDS. New York: Garden Way, 1991.

Schneck, Marcus. YOUR BACKYARD WILDLIFE GARDEN. New York: Rodale Press, 1992.

Schultz, Warren. THE CHEMICAL-FREE LAWN. New York: Rodale Press, 1989.

Stein, Sara Bonett. PLANTING NOAH’S GARDEN: FURTHER ADVENTURES IN BACKYARD ECOLOGY. New York: Houghton Mifflin, 1997.

Swain, Roger. EARTHLY PLEASURES: TALES FROM A BIOLOGIST’S GARDEN. New York: Lyons Press, 1994.

Tufts, Craig, and Peter Loewer. THE NATIONAL WILDLIFE FEDERATION’S GUIDE TO GARDENING FOR WILDLIFE. New York: Rodale Press, 1995.

Xerces Society Staff. BUTTERFLY GARDENING. San Francisco: Sierra Club Books, 1990.

Many plant varieties are disappearing.

In addition to providing havens for wildlife, backyard gardeners can also play an important role in saving some plant varieties from extinction. Over the last few centuries, farmers and gardeners have given up many traditional food crop varieties in favor of new, hardier varieties that are easier to grow and ship.
United States, for instance, has shrunk from more than 7,000 to fewer than 2,000 — and less than a dozen types make up the bulk of what is available in stores. Similarly, farmers in North and South America once grew thousands of tomato varieties; today, most have been lost or exist as seeds stored by elderly gardeners.

To save these often tasty and beautiful “heirloom” varieties, an increasing number of dedicated gardeners are growing these threatened plants and sharing the seeds with others. These “seed savers” have rescued hundreds of varieties, including many that are considered culinary superstars. Two leaders of this grassroots conservation movement are Kent and Diane Whaley of the nonprofit Seed Savers Exchange in Decorah, Iowa . The couple founded the Exchange in 1975 after an elderly, terminally-ill relative asked them to safeguard precious garden seeds brought from Bavaria four generations earlier. Today, the Exchange protects more than 13,000 endangered vegetable varieties, 700 old-time apples and 200 hardy grapes.

Plant breeders believe some of these old varieties hold genes that will allow them to create new, tastier crops that resist drought and disease, and require fewer chemicals. So far, 1,000 people across the country have joined the Seed Savers Exchange, using the organization’s newsletter and periodic meetings as a central clearinghouse for sharing information on growing treasured varieties and swapping rare seeds. The group also publishes a catalog and other materials that explain where to find heirloom varieties and how get started in seed saving. To become a conservator yourself, contact the Seed Savers Exchange. A winner of one of the MacArthur Foundation’s “genius grants” for his seed-saving work, Kent Whaley believes that gardeners committed to saving these seeds are providing insurance for the future. “It’s genetic treasure,” he says.

You can easily lure wildlife to your garden.

Growing a garden with plenty of nooks and crannies for critters isn’t that difficult. So says the National Wildlife Federation’s Heather Carskaddan, who has helped create more than 20,000 wildlife-friendly yards through the group’s Backyard Wildlife Habitat Program. “You need four key elements in your garden to attract wildlife,” she explains. “Animals need food, water, cover, and places to raise young.”

To feed the animals, one should plant species that produce flowers, fruits, nectar, nuts, and seeds at different seasons. Be aware that some animals prefer specific plants. Goldfinches, for instance, are attracted to thistles and other seed-bearing flowers, while hummingbirds prefer bright, nectar-rich flowers, such as columbine, bee-balm, and trumpet vine. Butterflies can be particularly picky, says naturalist Craig Tufts of the National Wildlife Federation: “Native butterflies have very limited food preferences, but if you put the right plant out it’s like a beacon.” Monarch butterflies, for instance, prefer laying their eggs on milkweed, because that is what they eat at their caterpillar stage. For gardeners not sure where to start, many commercial suppliers now package seed combinations geared toward attracting butterflies, birds, and even bats.

A water source like a birdbath, dripping hose, or even a puddle can be enough to slake the thirst of birds and butterflies, but if you really want an adventure, Tufts says, build a small pond in your backyard. “It surprises people how fast a water garden is colonized — it’s as if the dragonfly larvae and frogs parachute in,” Tufts says. “You wake up one morning and discover a chorus of breeding toads.” Sometimes, providing good cover for wildlife means being what some people might consider a messy gardener. Cavity-ridden dead trees, brush piles, and tangled bushes can all provide much-needed homes to some species, but too often, gardeners clean them out in favor of a tidy appearance. For those in cold climates, planting evergreens can provide winter shelter not offered by trees and bushes that lose their leaves.

A lawn provides poor cover for most animals.

Carskaddan encourages wildlife gardeners to use plants native to their area. Animals recognize these plants, “and since they are adapted to your region, you can use fewer chemicals and less water” as you garden, she says. She also urges gardeners to reduce both their use of pesticides and the size of their grass lawns as much as possible. “[Lawns] are considered biological deserts because they are single-species monocultures,” she explains. “By getting more creative, you can provide different levels of cover for everything from tiny voles to larger birds.”

Biologists caution that some animals are simply unable to adapt to life around people, such as warblers that require quiet, mature forests or salamanders that need a large, moist habitat. Even the most wildlife-friendly garden won’t be able to attract these creatures. In fact, scientists note that the most common garden life — weeds, crop-eating insects, and birds that thrive near structures — tend to be generalists, able to feed and nest in a wide variety of areas. Some go as far as to call these highly-adaptable organisms “weed species,” because they can thrive almost anywhere. “Weeds” or not, the average gardener generally welcomes the sight of brilliantly-hued cardinals and blue jays feeding in his backyard.

In addition, researchers say, a wildlife-friendly garden can help discourage many unwanted pests, like plant-eating aphids, by attracting the insects’ natural predators. “One of my favorite examples is what can happen when gardeners don’t spray pesticides,” says Tufts, who notes that although chemicals do get rid of unwanted pests like aphids, they also kill the insects’ natural predators, who may do the job more effectively. After gardeners who decide to shun pesticides stop using them, Tufts says, aphid populations may increase at first, “but soon a whole army of predators arrives, from ladybugs and lacewings to serpentflies and mummy wasps. Most people can’t believe that all these things are suddenly eating aphids — and all kinds of other pests, too!” he adds.

Here, the extraordinary lurks just beyond the ordinary — from amorous snails and hedgehogs to ravenous slug-eating beetles, choking creeping vines, and courageous mother bugs. Even seemingly innocent flowers hide lethal, perfectly-camouflaged predators among their folds, eager to snatch an unsuspecting bee from its nectar meal. And that warm, brushy compost pile? It could actually be a nursery for baby snakes, who wait inside their eggs for just the right conditions to slither out. The presence of snakes is just one sign that you’ve got a garden that does more than please the eye: it also provides an important habitat for plants and animals whose original homes may no longer exist.

“When people open their eyes, they can be amazed at what they can find in their own backyards,” says Craig Tufts, Chief Naturalist of the National Wildlife Federation in Vienna, VA and an expert on garden ecology. “If you look closely, you will see things you have never seen before — even though they’ve been there all along,” he explains.

“People often don’t realize what is right outside their doors,” adds Heather Carskaddan, who manages the Federation’s Backyard Wildlife Habitat Program, which encourages people to create yards that are attractive to wildlife. City and suburb dwellers “are disconnected from the landscape,” she believes. “They spend a lot of time in the car and in the house watching TV, instead of out romping around.”

A bit of garden snooping, however, can reveal sights more entrancing than a late-night movie. Fans of Westerns, for instance, may enjoy watching several kinds of common ants as they “wrangle” aphids, herding the tiny sap-sucking insects along plant stems in order to harvest the sweet, dewy nectar that aphids produce as waste. In return for the snack, researchers believe, the ant “cowboys” protect the aphids from predators. Horror-film aficionados should keep an eye out for a species of parasitic wasp that waits until its caterpillar prey is at a vulnerable stage, just before transforming into a hard-shelled larva, to inject its eggs into the caterpillar’s flesh; a few weeks later, the baby wasps hatch and eat their way out of their grisly nursery. For heartwarming drama, look no further than the story of the courageous stink bug mother, who resolutely guards the eggs she has carefully attached to a leaf. Once her dozens of young have hatched, she stands over them like a shield, warding off invading ants and other predators. Then, like a mother duck, she leads her gaggle of hatchlings off to feed.

Finally, sports fans might enjoy the incredibly intense competition among plants for sunlight and growing space. In SECRET GARDEN, time-lapse photography, which compresses days into a few minutes, reveals a no-holds-barred contest for living space that rivals any scramble for a loose basketball. Writhing, twisting, and pushing, each weed races to get ahead of the others — and to leave the carefully-nurtured flower and vegetable opponents in the shadows.

People sometimes “have a very meager understanding of what is going on in their yards,” says Tufts, but “it doesn’t take much to begin to understand what is going on out there and how different plants and animals interact.” The first step to discovering your garden’s secrets, he says, is simply to begin looking.

Online content for Secret Garden was originally posted March 1998.