Orb webs, such as those spun by the European garden spider, can snare large and fast-flying prey.

Spider-Man isn’t the only person with an interest in spider silk. While Spidey uses the threads to zigzag from building to building, or to snare a bad guy, scientists are investigating silk for different reasons. And though researchers have learned a lot about silk by investigating spiders, insects such as caterpillars, ants and bees also have been studied for the sticky stuff. Scientists are even trying to get silk from animals such as goats.

It turns out silk might be good for weaving a lot more than shirts and ties. In the future, the silky fiber might be used to make supertough bulletproof vests and light but strong parachute cords. Silk also might work well for delicate tasks inside the body. Researchers are experimenting with using silk to support growing cells, the same way a construction crew builds scaffolding around a building to help keep everything in its place during construction. Silk might be a good material to give growing cells something to hang on to. 

Scientists think silk would be useful for so many things because it is both extremely strong and very elastic — it can be stretched a long way without breaking. Most of today’s strong, elastic fibers are made from petroleum products and there are harsh chemicals in the recipes for these fibers. If scientists can figure out how natural silk-makers make their threads, the harsh chemicals might not be needed.

Spider silk is an ideal material, says Randy Lewis of the University of Wyoming in Laramie. “If you can mimic it, you can eliminate an awful lot of the problems you have with all the man-made fibers that are currently available.”

Humans have been gathering silk not from spiders but from silkworms for hundreds of years. Silkworms aren’t worms at all, they are actually caterpillars, or the young, of the silk moth. When it’s time for a silkworm to turn into a moth, the caterpillar spins itself a cocoon out of one very, very long silk fiber. The thread from unraveling a single silkworm cocoon can be 600 to 900 meters long! That’s more than two times the height of the Empire State building!

Long ago, people learned how to raise silkworms together in farms. Silkworms don’t mind being crowded together, as long as they have food, like mulberry leaves. In addition to making a nice fabric for scarves and sheets, silkworm silk is also used by doctors for stitching up cuts. But silkworm silk has its problems. A silkworm covers its silk in sticky glue that holds the cocoon together. Sometimes humans have a bad allergic reaction to this glue. And silkworms spin only one kind of silk.

Spiders, on the other hand, don’t use a sticky glue. And spiders make many different kinds of silk.

“We love the silkworm,” says David Kaplan of Tufts University in Medford, Mass., who has been studying silk for many years. “But spider silk is so diverse — we want to exploit that.”

Most spiders like to be alone. When they are crowded in one place they sometimes eat each other. This makes it hard to have a “spider farm” for collecting silk. So scientists are studying how spiders make silk, with the hope that the technique can be copied, perhaps even in other animals.

Spiders are one of the oldest groups of animals on the planet — scientists have found fossils of spiders that are 380 million years old. Although they are often mistaken for insects, spiders, along with ticks, mites and scorpions, are arachnids. Unlike insects, spiders have eight legs, a two-piece body, and usually eight eyes of different sizes and shapes. Spiders don’t have chewing mouthparts. Instead they have fang-tipped jaws called chelicerae that are used to inject digestive enzymes into prey. These enzymes break down prey from the inside out. Humans would be in trouble without spiders — they eat many insects that people consider pests. And spiders are a very diverse group — more than 37,500 species of spider have been described (consider that there are only about 10,000 kinds of birds).

Most spiders have an abdomen made up of five different sections. The last two sections are where the silk-making happens. These sections of the lower belly are modified into special structures called spinnerets, which are sort of like faucets for silk. The silk is mixed in glands and then secreted out of the spinnerets. Spiders can’t shoot silk out for long distances the way Spider-Man does. Instead, they attach the emerging silk to something, like a tree branch, and then move away from the branch. This pulls the silk outward.

One spider usually has several different glands and spinnerets for making several different kinds of silk. In their webs, most spiders use dragline silk for the outer rim and spokes. Strong as steel, dragline silk is also used as a safety line when a spider falls from a high shelf or branch. For the inner part of the web, where an insect such as a buzzing fly might get caught, spiders use an extra sticky silk. They wrap these freshly caught snacks in another silk, called aciniform silk. Spiders use another silk, one that is very stiff, to wrap and protect their eggs.

Even spiders that don’t make proper webs make silk. Scientists recently discovered that tarantulas, which use burrows instead of webs as homes, make silk from spigots on the end of their feet!

The most studied spider silks come from the golden silk spider, Nephila clavipes, and the European garden spider, Araneus diadematus. A one-inch-diameter fiber made of dragline spider silk could reel a 747 airplane from the sky, says Randy Lewis. The silk is also light and thus an excellent material for things like body armor, parachute cords or even tethering planes to an aircraft carrier.

Spider silks also seem to be useful inside the human body, says Kaplan.  For example, scientists have made ultrathin films out of dragline silk that in the future might be used as bandages for dressing wounds. Spider silk is also being used to make porous, or holey, gels and sponges. When placed in these sponges, tissue, bone and nerve cells are held steady while they grow. These silk sponges will fall apart or degrade gradually, after the cells have been given enough time to grow.

The main ingredient in spider silk is proteins, and there are many different kinds, depending on which spider is spinning and which silk it wants to make. Some of the proteins are very large and complicated, and therefore hard to make a lot of in the lab. So some scientists have put the genes that have the instructions for making silk into other creatures, such as goats. Some of these special silk-making goats live at the University of Wyoming. The silk-making genes are turned on only in the goat cells that make milk, so when these goats are milked, there is silk in the milk. Right now, it is hard to get a lot of silk in the milk, Lewis says. A liter of milk may have only 15 grams of silk, which means it would take about 600 gallons of milk to make one bulletproof vest. At higher concentrations the milk starts clumping, perhaps because the silk proteins are sticking to milk proteins, Lewis says.

Tara Sutherland, of Australia’s Commonwealth Scientific and Industrial Research Organization in Canberra, is focusing on silks made by insects other than silkworms. Many insects make silk, although only one kind each. Sutherland has zeroed in on the silks of bees, wasps and ants.

“Imagine a hive and each new generation of bees being wrapped in a silken cocoon,” she says. “If you remove the wax and look where the bees were raised there is silk — beautiful sheets of golden silk.”

The bee silk probably protects the baby bees in the hive, says Sutherland. Bee silk might also add structural support to the hive and prevent the wax from getting so warm that it melts.

Sutherland is also investigating weaver ants, which use silk to stitch leaves into nests. It seems only the baby weaver ants make silk. The adults hold the little larval silk-makers, moving them around for desired silk placement.

The silks made by stinging insects such as bees have a different structure from other silks. It looks like spiraled pasta versus flat sheets of linguini, says Sutherland.

And bee and ant silk is both tougher and more stable than silkworm silk, she says. Though nothing beats spider silk, because bee silk is made of simpler proteins, it might be easier for scientists to make in the large amounts needed to create everyday things for humans.

So watch out villains — Spidey may one day be upstaged by other silk spinners. Here’s to Ant-Man, or The Bee.

Going Deeper:

Christopher Sauer won first place and a twenty thousand dollar scholarship in the 2008 SSP Middle School Program. Here he discusses his project with students from Stuart-Hobson Middle School at the Marian Koshland Science Museum in Washington, D.C.

Have you ever noticed something — like ants in your backyard, or a smoke from a forest fire, or the moon at night — and thought to yourself “I wonder…?”

These two words can lead to a science adventure and they recently brought 30 middle school students to Washington, D.C. There, in the nation’s capital, these students spent four days participating in scientific challenges. These challenges were part of the Society for Science & the Public’s science competition for middle school students. Five of the students won top prizes, and were announced as winners of the 2008 SSP Middle School Program at an evening awards banquet in Washington, D.C. on October 21.

A lot of science involves wondering about something, coming up with ideas about that thing and then testing the ideas to see what you can discover. Science fairs at school are a good way to explore an idea. This year, more than 75,000 middle school students participated in science fairs at schools across the country. Judges for the SSP Middle School Program evaluated these students’ projects and sent the 30 students who had super-duper projects to Washington, D.C.

Once in D.C., the 30 finalists spent four days working on scientific challenges. One of the challenges was figuring out how an infectious disease like the flu might spread from person to person. Each finalist was also interviewed by the judges. Students were judged on their scientific knowledge, ability to understand new ideas and scientific and analytic thinking. They were also judged on their teamwork, leadership and communication skills. Here are the five top winners of this year’s program:

Christopher Sauer, 13, of Portola Valley, Calif. won first place, a $20,000 scholarship. He was selected as a finalist based on a team science fair project that involved building a simple engine called a magnetohydrodynamic drive. Christopher and his friend came up with the idea after watching a movie about submarines that use this kind of engine. The engine works when electric and magnetic fields thrust seawater out of a chamber, which propels the vehicle forward.

Taking home second place, a $5,000 scholarship, was Katherine Glockner, 14, of Encinitas, Calif. Katherine won a finalist spot for her project that investigated how smoke from the 2007 San Diego County fires affected area grade-schoolers’ lungs. To determine this, she tested the lung function of 149 students in grades four through eight. She also used questionnaires to gather information about each student’s activities during the week of the fires.

Brittany Wenger, 13, of Bradenton, Fla., came in third place, winning a $2,500 scholarship. She created a computer program that combined her interests in neural technology and soccer. Brittany’s program had a soccer team that “learned” as it played. The team eventually got good enough to beat a regular computer soccer team that couldn’t learn.

Winning fourth place — a Vernier LabQuest and $150 in gift cards — was Luke Andraka, 13, of Crownsville, Md. The project that brought Luke to Washington, D.C. began when he noticed that the water where he was whitewater rafting was very orange. Luke learned the waters were very acidic from acid mine drainage, a problem that can sometimes be helped by adding limestone gravel. Luke hypothesized that very tiny pieces of limestone would lessen the water’s acidity better than larger chunks of limestone.

Elizabeth Karron, 12, of Whitefish Bay, Wis., won fifth place, a $500 gift card to Barnes & Noble. Elizabeth investigated two species of duckweed, tiny aquatic plants that often grow together in lakes and ponds. She conducted experiments that showed how the two species compete in environments with small, medium and large amounts of nutrients.

So the next time you find yourself saying “I wonder…,” spend some time thinking about how you might explore your idea further. You never know where your curiosity might lead you — perhaps to Washington, D.C.!

Going Deeper:

A jellyfish’s stinging cells can give you a rash and can even make you very sick. But usually the creatures won’t attack you. “You just need to be careful around them,” says Jennifer Purcell of the Shannon Point Marine Center in Anacortes, Wash. Purcell has been studying jellies for 30 years.

“I have never been afraid of them,” she says. “I treat them with respect, and if I am going to be around them I wear gloves or some kind of covering.”

Purcell even has a favorite kind of jelly: the baseball-sized crystal jellyfish Aequorea victoria. When this graceful, almost transparent creature is disturbed, it glows along the inner edges of its umbrella-shaped body. “It looks like it has bicycle spokes radiating out,” says Purcell.

But crystal jellies aren’t the only ones that intrigue Purcell and other scientists. In recent years, massive groups of different jellies have started appearing in places that don’t usually have so many. And they aren’t always welcome. Jellyfish are clogging pipes that bring water into power plants. Big floating clumps of the animals are getting caught in fishing nets. These jellyfish sometimes kill the fish that have been caught and damage the nets.

Fishermen use bamboo poles to push giant jellyfish out of a net. Normally, a fisherman might catch one or two giant jellyfish in a week, but during “bloom” years he may catch more than 1,000 in one net.

Masato Kawahara

Fishermen worry about these huge groups of jellies showing up in new places. Such a swarm of jellyfish causes problems for the fishermen, who sometimes have to stop fishing for days and may get stung while cleaning their nets.

The changes in jellyfish habits are also worrying scientists like Purcell. They have a lot of questions about what is causing these jelly swarms. Has something changed in the oceans? What effect will the jellies have on fish and other marine life? Will we keep seeing more and more jellies in new places? Or is this just a temporary change that is part of a larger cycle of wind and weather?

Giant jellies in Japan

One jelly that has been a problem for fishermen is the giant jellyfish (Nemopilema nomurai). It is usually found in waters off of Japan and southeastern China. The giant jellyfish is one of the largest; it can grow up to 2 meters across (about 6 and a half feet) and can weigh as much as a grizzly bear (more than 500 pounds)!

The giant jellyfish can weigh as much as a grizzly bear. Since most people don’t like to eat the giant jellyfish (it isn’t crunchy enough), its presence is causing lots of problems for fishermen. One of the scientists studying the giant jellies in Japan l

Masato Kawahara

The giant jellyfish is usually found in small numbers, but in recent years there have been “blooms” of this jelly—thousands of them crammed together in one place. When the population size of a critter grows so quickly, scientists uaually look at the environment to see if something changed that made it easier for the critter to live there.

Jelly growth

Swarms of giant jellyfish bloomed in Japanese waters in 2002, 2003, and 2004. Afterward, Masato Kawahara from the Oki Marine Biological Station and other scientists in Japan started to investigate the gelatinous beast. The researchers collected its eggs and grew them into jellies in their lab. They paid special attention to how fast the jellies grew in different water temperatures.

Kawahara learned that when the water suddenly got warmer, it caused a change in the jellyfish lifecycle.

Normally, tiny young jellyfish spend their early lives anchored to a rock or the bottom of the ocean. At this stage, they look like little shrubs with tentacles. Then they mature into the more familiar free-floating critters. The Japanese team found that a spike in water temperature caused the young jellies to grow faster. It also triggered a sooner change from anchored jellies to free-floating jellies.

The team also looked at the water currents around Korea, China, and Japan. They think the giant jellyfish babies are born close to the coast. Later, a powerful flow of warm water known as the Tsushima Current carries the baby jellies more than 2,500 kilometers (about 1,500 miles) into the Sea of Japan. That’s a long way—roughly equal to the distance from New York to Colorado.

This current has strengthened in recent years. It usually helps fishermen by bringing a lot of fish, such as horse mackerel. Now fishermen and scientists are watching and waiting to see if the currents will bring more jellies than fish.

Hungry jellies

Off the coast of Alaska, another group of researchers looked at populations of the jellyfish Chrysaora melanaster in the Bering Sea. The UFO-shaped body of these jellies often has a pinkish-orange glow and long tentacles that can stream 5.5 meters (about 18 feet) behind them.

Scientists and fishermen who were working in the Bering Sea in the 1990s were seeing a lot of these jellies, so they decided to do an official count and see what the jellies were eating. Led by Richard Brodeur of the Northwest Fisheries Science Center in Oregon, the team surveyed different sections of the waters. They used trawls, which are large nets towed behind boats. Trawls scoop up everything in their path. After counting jellyfish picked up by the trawls, the scientists examined what was in the jellies’ stomachs.

It turns out the jellyfish ate a lot of little plankton. These are microscopic marine critters and plants that many fish also eat. The jellies ate some baby pollack too. This fish used to be plentiful in the Bering Sea. Pollack grow to about 60 centimeters (around 2 feet) long, and are an important food fish. They are often the fish in fish sticks and fish sandwiches at fast-food restaurants). But the scientists also found that when the pollack got a little bigger, they used the jellyfish for shelter! The jellies protected the young fish from birds, fish, and other animals that might eat them.

A large catch of Pollack fish.

iStockphoto

Then, in 2000, many fewer jellies showed up in the Bering Sea, Brodeur says. The drop is “probably caused by the drop in plankton production,” he says. Brodeur thinks that as the Bering Sea has warmed, there are fewer plankton for the jellies to eat. That may be why there are fewer jellies now. No one knows what that means for the pollack.

Jelly-tons

Scientists are also keeping an eye on creatures known as comb jellies. Distant cousins to the true jellyfish, comb jellies don’t have stinging cells. Instead they make special sticky cells that help them catch food.

Comb jellies, like Beroe forskalii, move by waving hair-like projections in their “combs” which stretch between their mouth and anus. Although sponges are generally considered to be the first multicellular animals, new evidence i

Steve Haddock

One species of comb jelly, Mnemiopsis leidyi (pronounced NEE-mee-OP-sis), is a native of coastal waters from Massachusetts to Argentina. In the 1980s it invaded the Black Sea, a large inland sea between Turkey and Europe. The population of Mnemiopsis grew and grew. By 1989, researchers estimated that the weight of all these comb jellies in the Black Sea was 1 billion tons; that’s about equal to the weight of all the fish caught in all the oceans that year.

Again, fishermen were worried. There were about 400 comb jellies per cubic meter (that’s like 200 golf ball–sized jellies in a space as big as a bathtub). After the comb jellies arrived, the anchovies—a slender, silver saltwater fish—almost disappeared. At first scientists thought the comb jellies were eating the anchovies. But Purcell says the comb jellies are probably eating lots of the anchovies’ food, not the fish themselves. This comb jelly has since spread again. Today it can be found in the waters off Norway and in the Mediterranean Sea.

Jellies in the Web of Life

Purcell recently reviewed several studies that looked into the changing jelly populations. Some of the studies linked warmer waters to the expanding populations. But it is important to remember that warmer waters affect everything in the food web, not just jellies, she says. An especially warm springtime leads to warmer ocean water temperatures. This means the tiny plants and animals that make up plankton grow faster. That’s good for critters that eat plankton.

The spotted jelly, also known as the lagoon jelly because it likes to live in harbors and lagoons, has many little mouths on its oral arms. Small fish sometimes live inside the bells of large spotted jellies, where they are protected from predators.

Alvaro Migotto

“A warm spring can be good all around for the jellies,” Purcell says.

Purcell also points out that jellies play an important role in the oceans. Turtles and many fish, like the chum salmon, eat jellyfish. Jellies are also food for humans. In China, farms have been set up to grow the edible jelly Rhopilema esculenta, which is enjoyed as an appetizer with salad greens and vinegar. (Once they are cooked “jellyfish have no taste, just crunch,” says Kawahara, who studies the giant jellyfish in Japan.)

In her new study, Purcell points out that humans are changing the environment in many ways that might lead to more jellyfish. More and more power plants are being built, which often warm the waters nearby. More fish farms are being built, which can add a lot of nutrients to waters. This can lead to more plankton and more food for jellies. There may be fewer jellyfish in places like the Bering Sea, but there now may be more in other parts of the oceans.

Today, scientists still have more questions than answers about what is causing the changes in jellyfish numbers around the world. But through careful studies, researchers hope to find out more about the jellyfish blooms and what the blooms can tell us about the health of the oceans.

Jelly vs. jellyfish: What’s the difference?

All jellyfish are considered jellies, but not all jellies are jellyfish. What gives? It turns out that having a body made of jelly doesn’t necessarily mean you are a jellyfish. For example, the animals known as comb jellies look in many ways like true jellyfish, but are actually distant cousins. Comb jellies have different bodies than true jellyfish and don’t make the stinging cells that jellyfish do. These stinging cells are called nematocysts (neh MAT oh sistz).

Scientists are still trying to figure out a lot about the sea’s gooey creatures, and the different kinds of jellies can be hard to tell apart. The true jellyfish are called scyphozoans (sigh-fuh-ZOH-unz) and are a kind of jelly. Then there are two groups of close relatives—box jellies and hydrozoans (HIGH-druh-ZOH-unz). While they are very close relatives of the true jellyfish and they have the same stinging cells, scientists don’t consider them true jellyfish.

The small but fast Cladonema pacifica is a hydrozoan.

Alvaro Migotto

Jellyfish and their relatives the box jellies and hydrozoans are very simple animals. They don’t have brains or hearts or lungs. But they do have a thin layer of muscle. They swim by squeezing this muscle, which forces water out the bottom of their bell, propelling them forward. Scientists think that jellyfish were the first animals on earth to use their muscles to swim.

The four-tentacled box jelly lives in waters around Australia, Malaysia and Japan. Also known as the jimble or sea wasp, its sting is quite painful. Although box jellies are not true jellyfish, they are very close relatives.

Alvaro Migotto

Most small jellyfish eat plankton and floating bits of food. Larger ones will eat fish and other small animals that they stun or kill with their stinging cells. Then they bring food to their mouths with tentacle-like structures called oral arms. Many jellyfish will glow when they are bumped or disturbed. They make a special protein that gives off light.

Additional Information

Word Find: Jellies Mania

Going Deeper:

Scientists are still trying to figure out a lot about the sea’s gooey creatures, and the different kinds of jellies can be hard to tell apart. The true jellyfish are called scyphozoans (sigh-fuh-ZOH-unz) and are a kind of jelly. Then there are two groups of close relatives—box jellies and hydrozoans (HIGH-druh-ZOH-unz). While they are very close relatives of the true jellyfish and they have the same stinging cells, scientists don’t consider them true jellyfish.