This type of algae is kelp, and kelp forests are sometimes called the rainforests of the seas. This kelp forest is in Monterey Bay off the coast of California.

Tania Larson, U.S. Geological Survey

Algae may be easy to see, but appearances can be deceiving. There’s an ongoing problem with algae that has pestered scientists ever since they started trying to organize and classify the natural world. Different types of algae may look similar, but they’re actually very different organisms.

Algae may range in color from red to brown to yellow to green. Some types, like phytoplankton, are tiny and visible only under a microscope. Others types, like giant sea kelp, can grow to over 100 feet. Some types of algae are unicellular, which means the entire organism is made of one cell; others are multicellular.

Diatoms are one of the single-celled types of algae. Pictured is a scanning electron micrograph image of Diploneis puella.

USGS Geology and Environmental Change Science Center website

Strangest of all, there are types of algae that sometimes behave like plants — and sometimes behave like animals. Like a plant, these algae use photosynthesis to make food. (During photosynthesis, plants or algae use light from the sun to turn carbon dioxide and water into oxygen and food.) But when sunlight is not available, these organisms can still survive by eating other organisms — including other algae! (What would you call that? Cannibalgae?) That behavior is more like an animal because animals can’t synthesize their own food.

Algae are notoriously difficult to classify. So much so, say some scientists, that maybe the best idea is to stop using the word “algae” altogether — except that it’s been around so long it’s too late to change.

Your cousin Chlamy

In 2007, an international team of biologists looked at all the genes of a simple green alga called Chlamydomonas reinhardtii, or Chlamy for short. Genes carry the instructions of life “written” on tightly coiled molecules called DNA inside every cell. Chlamy’s genetic “instruction book” has about 15,000 genes, which is about 8,000 fewer genes than in humans. When the biologists compared Chlamy’s genes to other organisms, some interesting trends emerged.

A large number of Chlamy’s genes can also be found in flowering plants. But it might be surprising to know that roughly 35 percent of Chlamy’s genes can be found in both flowering plants and humans, the research team reported earlier this year. Plus, about 10 percent of Chlamy’s genes can be found in human cells but not plant cells.

No one is going to invite Chlamy to the family reunion, of course. And Chlamy isn’t that unusual — many different living things have identical genes. But Chlamy is interesting: It shows how evolution can deliver some surprising tricks, like producing algae that is genetically similar to humans and plants.

A red tide is a poisonous bloom of algae that can kill marine life.

NOAA

Scientists have always had trouble classifying algae. In ancient Greece, the philosopher Aristotle — probably the first scientist to try to organize all living things — simply placed algae in with plants. (Plants and animals were “beneath” humans, and humans were “beneath” angels.)

In the 18th century, a Swedish botanist named Carl Linnaeus suggested a system that grouped all plants together and grouped all animals together. Like Aristotle, Linnaeus called algae a plant. Linnaeus’ system also showed how similar animals — such as dogs and wolves, for example — could be grouped together. The system is still in use today, though it has been modified and changed significantly in the past 250 years. But even with hundreds of years of changes, algae stick out like a sore thumb.

“The study of algae has changed a lot, but it has always been a problem,” says Rick McCourt, a biologist at the Academy of Natural Sciences in Philadelphia. McCourt is also a phycologist, or a scientist who studies algae. (Phycology is the study of algae.)

McCourt points out that the algae problem goes back much farther than Linnaeus or even Aristotle. Much farther: The roots of algae’s identity crisis go all the way back to the beginning of life on Earth, billions of years ago.

Bacteria move in

About 3 billion years ago, Earth was a different planet. It was not populated by people, animals or plants, and the atmosphere was mostly carbon dioxide. Earth’s inhabitants were microorganisms such as bacteria, so small they’re impossible to see without the help of a microscope.

So how did that Earth become the planet on which we live? Many scientists who study evolution blame one particular organism called cyanobacteria. (Sometimes known as blue-green algae or blue-green bacteria, these microorganisms were grouped together with algae until just a few years ago.)

When cyanobacteria, or blue-green bacteria (pictured is the cyanobacteria Gloeotrichia stained with sytox green), invaded another organism, algae was the eventual result.

Barry H. Rosen, USGS

“Blue-green bacteria changed the world more than any other group of organisms,” says Brent Mishler, a phycologist at the University of California, Berkeley. Blue-green bacteria were capable of photosynthesis, he says, which means they started taking carbon dioxide and adding oxygen to the atmosphere.

Scientists think that blue-green bacteria are also responsible for algae. Here’s how: These bacteria may have been the first organisms to stay alive through photosynthesis. That means they used sunlight, water and carbon to make their own food.

Other organisms regularly fed on the blue-green bacteria as well. One of these organisms was the ancient ancestor of green algae. But this ancient alga wasn’t green back then — it was colorless.

And one time, when this algal ancestor ate one of these blue-green bacteria, something strange happened. The organism didn’t digest the bacteria — it absorbed it.

Instead of becoming dinner, that bacteria became a permanent resident inside the other organism. Biologists believe that bacteria-inside-an-organism is the oldest ancestor of all green algae. These two organisms each had their own set of genes, but after millions of years and many, many, many generations, the genes mixed and both sets became essential for the alga’s survival. The two organisms had become a single organism.

“It’s the only explanation that makes sense,” says McCourt. “Everything we call green algae descended from a single ancestor, maybe from a single cell, long ago in the ocean or in the freshwater.”

Green algae isn’t the only type of algae. Other types — including brown algae, red algae and diatoms — also evolved in a similar way. “What makes all the algae groups algae is that some of the cyanobacteria went and lived inside them,” Mishler says. “But they were invaded separately.”

Different types of algae may not be related in ancient, ancient history, but every type of algae evolved from an organism that, once upon a time, was invaded by blue-green bacteria. These invaded organisms were not necessarily similar. Green algae and brown algae, for example, are often grouped together because they both use photosynthesis to make food, and because they’re both found in the water. But they have very different family histories. Green algae evolved after one type of organism was invaded by cyanobacteria, and brown algae evolved after a different organism was invaded.

This distinction explains why there are so many different kinds of algae — and why the algae family is still hard to pin down. Scientists have shown that many different types of algae are related only distantly, despite the fact that they may look similar.

And some of these scientists say algae’s classification problem isn’t with algae at all, but with the system we use to organize living things. These scientists advocate for a new system — one based on evolutionary ancestors, rather than on the current appearance and structure of an organism.

Changing classification systems

The original invasion that gave us algae happened billions of years ago, but since then, algae’s evolutionary story has been filled with similar invasions. Even today, it’s easy to see how algae too have invaded other species.

Mishler points out that algae are responsible for the brightly colored plumes that can be observed on giant clams or the vibrant appearance of coral. Algae also live inside octopi. “There’s a parallel story over and over again, with algae invading a host,” says Mishler. “They like to live in other organisms.”

Earlier this year, scientists found an invasion in the making: A sea slug that regularly feasts on algae was found to have absorbed algal genes — the ones used to do photosynthesis.

But just because the invader is the same for all these host organisms doesn’t mean the host organisms are related; it just means they’ve been invaded. And if the evolutionary development of algae is considered, then maybe “algae” shouldn’t be its own group of organisms.

Some biologists, like Mishler, say it’s time to change the system that we use to organize the living world. A better way, they say, would be to organize living things according to how they evolved.

The problem in classifying algae is just one example of the issues that scientists who care about naming things grapple with. And their work is just starting. Dozens of new plant and animal species are found every year, and each one of those new species has to be studied, classified and named.

The system for classifying organisms also gives those organisms their names. It’s important that scientists agree on the same names. “Unless you can name something you really can’t talk about it,” says McCourt. “Giving a species a name is necessary in order to study and understand what it’s doing.”

“If a young scientist wanted to get a good career and go outside and do adventurous things, this would be an exciting career,” says Mishler. “It’s one of the older careers in biology, but it’s still not finished.”

And there will always be new species to find: “There are probably more organisms out there we don’t know than those we do know,” Mishler says.

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Chances are, though, you’ve come face-to-face with plenty of these crusty, leafy, or shrubby growths. Lichens live on rocks, branches, houses, even metal street signs. You can find these often colorful organisms almost everywhere—from deserts to rainforests, Antarctica to Africa. They’ve survived trips to outer space, and some scientists suspect there might even be lichens on Mars.

“If you go into your backyard, you will definitely find a lichen somewhere,” says Imke Schmitt, a lichen researcher—called a lichenologist—at the University of Minnesota, Twin Cities.

What you probably don’t realize is that a lichen is more than a single thing. It is a thriving relationship between two different types of living organisms: a fungus and an alga. Neither of these organisms is a plant, so the lichen isn’t a plant either.

Different species of lichens can look very different from each other. Thorsten Lumbsch, a lichenologist at The Field Museum in Chicago, took photographs of two varieties of lichens—a rock lichen (above) and a spot lichen (below)—during a recent

Thorsten Lumbsch

Thorsten Lumbsch

Through photosynthesis, the alga harvests the sun’s energy to make food for the fungus, which provides a place for the alga to live. But the relationship is lopsided, Schmitt says, with algae caged like prisoners—even slaves—inside their fungal hosts.

Around the world, scientists have identified tens of thousands of types of lichens. At least as many probably still await discovery, says Thorsten Lumbsch, a lichenologist at the Field Museum in Chicago.

“Even in North America, there is a huge lack of knowledge” about lichen diversity and biology, Lumbsch says. “There’s a lot still to discover.”

As lichenologists continue to find new species of lichens, they are also working to understand how various species are related to one another. By putting together a lichen family tree, they hope to understand why so many different types of lichens have evolved in so many places around the world.

Most research involves attempts to understand basic facts about the organisms and their interrelationships. But researchers are also teaming up with lichens to monitor the health of the environment, among other applications.

Tough work

Studying lichens is rarely easy. Most species depend on very specific conditions, and scientists can rarely get them to grow in laboratories. This provides lichenologists a great excuse to travel around the world, scouting new specimens and insights.

Lumbsch, for one, makes several trips to Australia and South America each year. In the field, he searches for a group of crusty lichens that tends to be quite tiny—usually less than a few millimeters long. Finding samples takes patience and a trained eye.

“You have to look very closely,” Lumbsch says. “Usually, I know which species I’m interested in and which habitats they grow in. So, I go there and crawl on my knees on the forest floor with a hand lens.”

Like many lichenologists, Lumbsch (far right) travels all over the world to collect specimens. This photograph was taken on a research trip to India in January 2008.

Thorsten Lumbsch

Spotting lichens is challenging enough. Identifying them is even harder. Many species look exactly alike, even when they are only distant cousins. Closely related species, meanwhile, can live in totally different environments, or on opposite ends of the Earth. (One species, for example, is found only near both poles.)

When they’re done collecting samples, lichenologists bring their catch back to the lab. Under a microscope, the researchers classify samples by structure and color. Then, they grind specimens into a powder, from which they extract genetic material. These DNA molecules, which appear in all cells, make up genes, which determine how organisms look and work.

The more closely related two organisms are, the more similar their DNA will be. Comparing DNA from different species, then, can give scientists an idea of when each group split off from a common ancestor. Researchers use this information to build lichen family trees that depict kinship between species.

“Once we have these trees, we can ask a lot of interesting questions,” Schmitt says.

For example, family trees can help explain what the first lichens looked like, how they have evolved over time, and how far any given species has moved around the globe. Such insights should provide a window into our planet’s distant past. Some researchers think that lichens were the first organisms to live on land, long before plants evolved to do so.

“[Lichens] have an extremely long history,” Schmitt says. “This is what we are trying to uncover by building family trees.”

The work is slow going, she adds. “But we are beginning to see a picture emerging.”

Environmental police

Despite their reputation as scientific curiosities, lichens have a practical side. Throughout history, people have used different species to make dyes for fabrics, poisons for arrowheads, and “green”-smelling scents for perfumes. Birds use lichens to make nests. Reindeer and other animals, including some people, eat them. (Don’t try this at home—some species taste awful!)

In modern times, scientists have found a new role for these growths: as environmental watchdogs.

Although lichens can live in some of the harshest environments on Earth, Schmitt notes that they “are very sensitive to any kind of change that humans put on the environment.”

Some species of lichen are highly sensitive to changes in the environment.

Tsnena/Wikipedia

Studies show that some species quickly disappear when exposed to air pollution. These sensitive types also suffer from habitat loss due to logging, construction, or other environmental disturbances. The presence of lichens in an ecosystem, then, generally signals that the air is clear and the environment healthy. Their disappearance, on the other hand, can be a warning sign.

Lichens are good monitors of air quality. In fact, studies have shown higher rates of lung cancer in people who live in areas where sensitive lichens have died off. As a result, Lumbsch says, some European cities require developers to confirm the presence of sensitive lichens as a sign of habitable air quality before building new homes. Where lichens reside, city planners can feel confident that homeowners will have good air to breathe.

Among other projects, Lumbsch and his colleagues are looking at the effects of climate changes on lichen populations. Some day, he says, lichens might add service as global-warming sentinels to their list of accomplishments.

Lichens have long been overlooked. Chat with a lichenologist, though, and you’ll find plenty about these underappreciated growths to like, if not love!

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Word Find: Lichens—What’s not to like?

Going Deeper:

I had scanned a large, plant-filled enclosure several times before locating him: a 70-something-year-old tortoise named Lonesome George. The tortoise weighs 88 kilograms (nearly 200 pounds), but he was barely visible beyond several bushes, and his head and legs were tucked neatly within his shell.

An adult Galápagos tortoise lumbers within a semiprotected space at a breeding facility on San Cristobal Island.

Bryn Nelson

Like a stubborn child who refuses to leave his room, George is not the most sociable tortoise in the world. But he’s by far the most famous, and I was happy to spot him—or at least his shell. That’s because George is the last known member of his species, sometimes called the Pinta tortoise.

A special place

George lives in the Galápagos Islands, a group of 19 islands in the Pacific Ocean about 600 miles (a little less than 1,000 km) west of Ecuador. The islands are famous for their unique plants and animals. For example, many of the islands’ lizards, iguanas, tortoises, sea lions, seabirds, land birds called finches, and even a type of penguin, have been found nowhere else in the world.

Recent reports, however, suggest that many species in the Galápagos are in trouble. Scientists blame the growing problem on too much tourism, too many people moving to the islands, and the introduction of foreign plants and animals that are crowding out or killing native species.

Based on satellite photographs taken by NASA, this image shows the major islands in the Galápagos.

Wikipedia/NASA

But researchers and volunteers are working hard to save threatened animals such as the tortoises. Using a range of strategies, from radio collar–wearing goats to analyses of old tortoise bones, they are making a difference—and showing that a shy survivor named George may not be so alone after all.

The rarest creature

Before humans first arrived in the Galápagos Islands in the 1500s, 15 or more closely related tortoise species may have lived there. Twelve of those species still inhabit the islands, but two are extinct. Lonesome George is the last known member of the third.

A Galápagos tortoise shares a morning bath with a white-cheeked pintail in a duckweed-covered pool in Santa Cruz Island’s highlands.

Bryn Nelson

Scientists found George living alone on an island in the Galápagos called Pinta Island in the early 1970s. Because he is the last remaining Pinta tortoise that scientists know about, the Guinness Book of World Records has called him the “rarest living creature.”

I recently took a weeklong voyage through the Galápagos aboard a motor-powered yacht named the Letty. Aboard the boat, I met wildlife photographer Tui De Roy, who told me that several tortoise species were in even worse shape when she was a girl.

De Roy moved to the Galápagos Islands when she was 2 and lived there for more than 35 years. Now a resident of New Zealand, she helps oversee the Charles Darwin Foundation.

The foundation operates the Charles Darwin Research Station on Santa Cruz Island in the Galápagos. Scientists at the station advise the Ecuadorian government on how best to protect the Galápagos Islands.

By some estimates, De Roy says, up to 500,000 tortoises were killed for food or taken away as pets in the centuries before concerned people began protecting them. By the time preservation efforts began, perhaps only one-tenth of the original population remained.

Laws now protect the tortoises from hunting, but the lure of money still drives some people to kill the tortoises and sell their meat. Galápagos tortoises also face new dangers from animals that didn’t originally live on the islands, including goats.

Pesky goats

Over the past few centuries, fishers, pirates, sailors, and settlers brought goats to the Galápagos as a reliable food source. Unfortunately for tortoises, goats like the same types of grasses, fruits and leaves as tortoises do, and the goats are faster movers.

As the goats multiply, they beat tortoises to prime grazing spots. And they trample other favorite tortoise foods, like young prickly pear cacti.

As they stomp around, the hoofed animals can also squash sandy areas near the shoreline where tortoises build their nests. Over time, huge herds of goats can turn leafy forests into barren grassland.

This mural on the island of San Cristobal reads, “These introduced vertebrate animals are a menace in the Galápagos.” Pictured are a rat, cat, dog, pig, and goat—among the most destructive newcomers in the Galápagos Islands.

Bryn Nelson

Researchers have used helicopters, dogs, and even other goats to track down the goat invaders. The tracker goats wear radio collars that allow scientists and hunters to follow them as they mingle with wild goats. The researchers also put bright paint on the tracker goats, so hunters know to leave them alone but to nab their wild companions.

Goats be gone

The antigoat campaign has been paying off. Last year, researchers removed the last of an estimated 75,000 to 125,000 wild goats from the northern part of Isabela Island, which boasts more tortoise species than any other island in the Galápagos.

The victory built upon earlier successes on several other islands. On an island named Española, thousands of goats were removed in the 1970s, De Roy says. By then, the island’s native tortoise population had dwindled to 12 adult females and 2 males.

In the 1960s and early 1970s, researchers evacuated those few surviving tortoises to the Charles Darwin Research Station some 60 miles away. There, they set up an emergency-breeding program.

This male tortoise was once kept illegally as a pet. Now, he stretches out at the Charles Darwin Research Station on Santa Cruz Island.

Bryn Nelson

A third male tortoise from Española, named Macho, was already living at the San Diego Zoo. Scientists later brought him to the research station to help restore the island population. The descendants of Española have now helped resettle more than 1,400 tortoises on their goatfree native soil.

“Española is one of the most beautiful stories” of tortoise success, says Gisella Caccone, an evolutionary biologist at Yale University.

A stunning find

Earlier this year, Caccone and her colleagues announced another stunning discovery: Lonesome George may not be alone after all.

The discovery began with a routine study of the genetic material known as DNA. Every animal’s DNA is different, but researchers can look for common patterns among members of the same species that distinguish them from other species. A crow’s DNA, for example, looks significantly different from a hawk’s DNA, even though both creatures are birds.

First, Caccone’s team extracted a sample of DNA from George’s blood. The researchers also took DNA from the bones of long-dead Pinta tortoises that had been stashed away in museums for decades. By looking at samples of both living and dead specimens, the scientists came up with a profile of a typical Pinta’s DNA.

Next, the team compared the Pinta DNA with DNA from tortoises living on neighboring Isabela Island. They already knew the Isabela population had a mixed heritage, and they wanted to know more about where the ancestors of the Isabela tortoises had come from.

Their results surprised them. One young Isabela male tortoise, the scientists learned, shared half of George’s DNA. Caccone says that this discovery suggests that the youngster’s mom was likely born on Isabela Island. But his dad, like George, originally lived on Pinta Island, about 50 miles away.

No one knows how the tortoise father made the trip to Isabela. It’s possible that he and others rode to their new home with sailors or settlers, or on strong ocean currents. Unlike sea turtles, tortoises live only on land. Even so, tortoises have been known to survive for long periods in the ocean, whether floating by themselves or clinging to mats of vegetation. Some researchers, in fact, believe the first tortoises to arrive in the Galápagos Islands did so by floating westward from the mainland.

Either way, the new find has researchers hoping they’ll be able to identify more Pinta tortoises now living on Isabela—or at least tortoises that are partly descended from Lonesome George’s extended family. If they can find both males and females with Pinta DNA, scientists will start a new breeding program to pass on as much of that unique DNA to tortoise hatchlings as possible. If they’re really lucky, their breeding program may help the Pinta species survive. George, who seems completely uninterested in reproducing, would be off the hook.

These tortoise hatchlings are a few years old. Here, they seek shelter from the heat at the Charles Darwin Research Station on Santa Cruz Island in the Galápagos. Researchers have bred these hatchlings in captivity and will release them into the wild

Bryn Nelson

Caccone’s group has done more than revive the hope of rescuing Pinta Island tortoises from the brink of extinction. Two years ago, the team also discovered a previously unknown species of tortoise on Santa Cruz Island, where most people in the Galápagos Islands live. The isolated population of about 100 tortoises still doesn’t have a formal name.

“The Galápagos can yield an incredible amount of new surprises,” Caccone says. “Think what you can find when you really study well the other islands.”

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Word Find: Tortoise Hunt

It doesn’t take long before a hive is nearly empty. Researchers call this phenomenon colony-collapse disorder. According to surveys of beekeepers across the country, 25 to 40 percent of the honeybees in the United States have vanished from their hives since last fall. So far, no one can explain why.

Inspecting a honeycomb from a healthy hive (above), beekeeper Dan Geer finds bees densely packed. A honeycomb from a hive whose colony is collapsing (below) has far fewer bees.

Cutraro (both images)

Colony collapse is a serious concern because bees play an important role in the production of about one-third of the foods we eat, including apples, watermelons, and almonds. As they feed, honeybees spread pollen from flower to flower. Without this process, called pollination, a plant can’t produce seeds or fruits.

Now, a group of scientists and beekeepers has teamed up to try to figure out what’s causing the alarming collapse of so many colonies. By sharing their expertise in honeybee behavior, health, and nutrition, team members hope to find out what’s contributing to the decline and to prevent bee disappearances in the future.

Sick bees?

It could be that disease is causing the disappearance of the bees. To explore that possibility, Jay Evans, a research entomologist at the United States Department of Agriculture (USDA) Bee Research Laboratory, examines bees taken from colonies that are collapsing. “We know what a healthy bee should look like on the inside, and we can look for physical signs of disease,” he says.

And bees from collapsing colonies don’t look very healthy. “Their stomachs are worn down, compared to the stomachs of healthy bees,” Evans says. It may be that a parasite is damaging the bees’ digestive organs. The bees’ inability to ward off such parasites suggests that their immune systems may not be working as they should.

The honeybees have other signs of troubled immune systems, such as high levels of bacteria and fungi inside their bodies, says Dewey Caron, an entomologist at the University of Delaware. He’s one of the leaders of the colony-collapse research team.

But why would parasites, bacteria, or fungi in the body cause bees to leave their hives? After all, when you’re sick, you want to stay at home, right?

Caron says that some of these disease-causing agents may lead to disturbances in bee behavior. “It may be that sick bees are not processing information correctly and learning where home is,” he says. In other words, a sick bee might leave the hive and simply forget how to get back.

If enough of the bees in a colony can’t find their way home, he says, it’s just a matter of time before the colony collapses. Being social insects, even healthy bees are unable to live long on their own. And once the bees vanish, the crops that they usually pollinate are in trouble.

Environmental clues

Another cause of colony-collapse disorder may be certain chemicals that farmers apply to kill unwanted insects on crops, says Jerry Hayes, chief bee inspector for the Florida Department of Agriculture. Some studies, he says, suggest that a certain type of insecticide affects the honeybee’s nervous system (which includes the brain) and memory. “It seems like honeybees are going out and getting confused about where to go and what to do,” he says.

Adding to the mystery, Hayes says, is an observation about moths and other insects that frequently use empty beehives to raise their own young.

“Usually, they move right into an empty hive,” he says, “but now they’re waiting several weeks before they do.” As Hayes sees it, this suggests that something repellent in the hive may not only be driving out bees but also keeping other insects from moving in, he says. So far, scientists haven’t identified what that repellent thing could be.

Looking at bee genes

If it turns out that a disease is contributing to colony collapse, bees’ genes could explain why some colonies have collapsed and others have not. In any group of bees—or other animals, including people—there are many different kinds of genes, because each individual has a slightly different unique set of genes. The more different genes a group has, the higher the group’s genetic diversity. And genetic diversity is a plus as far as survival is concerned.

Some scientists are now studying genetic diversity in honeybee colonies to see if it has an effect on colony collapse disorder.

“If a colony is genetically diverse, it’s less likely the colony will be wiped out completely from a sweeping infection or disease,” says David Tarpy, a University of North Carolina entomologist. That’s because at least some bees in a genetically diverse group are likely to have genes that help them resist any specific disease that gets into the colony, he says. Scientists haven’t determined the role of genetic diversity in colony collapse, but it’s a promising theory, says Evans. He and his colleagues at the USDA bee lab are currently running genetic tests on bees from collapsing colonies. Their goal is to find out whether there are genetic differences between the bees that vanish and those that remain in their hives.

Beekeeping helps support these important, pollinating insects.

Cutraro

Scientists are working hard to figure out the causes of colony collapse. Meanwhile, bees continue to disappear. Can anything be done to help them survive?

Tarpy suggests that more people could raise bees to help restore their numbers. “Given this decline in honeybees, if you want to get active in helping to promote pollination, the best thing to do is to become a beekeeper and keep your own bees,” he says.

Don’t be put off by the possibility of a sting, says Dan Geer, who raises bees in North Smithfield, Rhode Island. First of all, beekeepers can wear protective gear. And bees, he says, have a bad rep. “You’d be surprised by how gentle they are,” he says.

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Going Deeper:

Shitake mushroom.

Robert L. Anderson, USDA Forest Service, www.forestryimages.org

Scientists do all of these things—and more. Mushrooms belong to a major group of organisms called fungi. Not quite animals and not quite plants, fungi are turning out to be full of mysteries and surprises.

Mushrooms pop up in forests at certain times of year in various places all over the world and then disappear completely without warning. Some are as big as a car. Others are too small to see without a magnifier. Their colors range from bright orange to purple to green.

To add to the intrigue, it turns out that fungi are more closely related to animals than they are to plants—even though they look more like plants. Some types even seem to have ingredients that fight cancer, though others can kill you.

“Once you get to know them, they really become interesting,” says mushroom researcher David McLaughlin. More than just an ordinary mushroom lover, McLaughlin is curator of fungi at the Bell Museum of Natural History in Minneapolis. He’s also a professor at the University of Minnesota in St. Paul.

McLaughlin and other fungi experts estimate that between 1 million and 1.5 million species of fungi exist on Earth. Yet, only about 10 percent of them have been identified and named.

“It’s amazing how little is known,” he says, “and how much there is to discover.”

Filaments and spores

A few basic traits tie all fungi together. Most are made up of threadlike structures called filaments. They feed on dead and dying organisms. To reproduce, they send out spores instead of seeds. And the mushrooms that we see (and buy at the store) are just the fruits of fungi. Most of a fungus stays hidden underground.

This microscopic view of a fungus that grows on corn roots shows its threadlike filaments and spores (round bodies). This sample has been dyed so that it glows green to make it more visible.

Sara Wright, USDA Agricultural Research Service

Across the fungus kingdom, however, there’s a large amount of variety—in looks, lifestyle, and flavor. Some are delicious, while others are poisonous. Some grow on trees, while most grow on the ground.

To get a better idea of exactly what’s out there, McLaughlin and his coworkers are pulling together all the data published about mushrooms over the last 40 years. They’re also building large computer databases to hold the information they collect.

In the end, the researchers hope to piece together a fungal family tree. The tree should help explain how various types of fungi are related to each other and how different species developed over the course of evolution.

“We’re trying to fill in holes in the data so that people can understand how fungi evolved,” McLaughlin says.

There are also practical reasons for creating a fungal family tree. Hundreds of kinds of fungi cause diseases in people, including ringworm and athlete’s foot. Some 5,000 types cause diseases in plants. Understanding which species are related to one another allows researchers to predict which ones might cause diseases and which ones might respond to certain treatments. Also, knowing how much diversity is out there is the first step in knowing if and when certain species start disappearing.

Diversity and DNA

McLaughlin uses various features of fungi to put them into categories, starting with the shape, size, color, texture, smell, feel, habitat, and manner of growth of the fungus itself and details of its cells, fruiting bodies, spores, hairs, and other structures.

Other researchers use modern advances in technology to classify fungi. By comparing the genetic material DNA in two different species, scientists can determine how closely related these species are.

Chanterelle mushrooms.

Theodor D. Leininger, USDA Forest Service, www.forestryimages.org

In one recent study, McLaughlin says, researchers took samples of soil from high elevations in the Rocky Mountains. They found fungal DNA in the soil and were able to use it to identify an entirely new type of fungus.

Taking a closer look at mushrooms is also revealing how much more there is than meets the eye in the wide world of fungi. “With new techniques, we’ve been able to say, ‘Oh my. We thought these were the same things. But now that we look closer, we’re able to say they’re not the same thing,’” McLaughlin says. “Everyone assumes that if it’s shitake, it’s a shitake. Well, a shitake is not just one thing.”

The porcini group, too, appears now to include at least 35 species living across the Northern Hemisphere, not one or two species as previously thought. That’s important because people have been using porcinis as medicine for thousands of years. These mushrooms have also been getting attention lately for their ability to destroy tumor cells. It’s possible that not all types of porcinis provide the same benefits.

Mushroom specialist David McLaughlin is working with medical researchers to see if certain mushrooms can prevent cancer.

Photo by Tim Rummelhoff, University of Minnesota.

Unfortunately, most of the studies previously published about these mushrooms are useless now, McLaughlin says, because the scientists didn’t keep specimens of what they were looking at. It’s hard to tell exactly which particular type of mushroom they were studying.

Creating a new, large database will help researchers accurately classify the fungi they are working on. Having such specific information about these fungi will make their results more useful to other scientists.

So, the fungi hunt continues, whether it’s to learn more about these fascinating organisms or simply to identify something good to eat.

Be careful, however. Don’t eat any mushrooms that you find in the woods without checking with a teacher, parent, or mushroom expert first. Some mushrooms are poisonous enough to kill you.

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