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Animal Helpers: Science's Newest Discoverers
by Mary-Russell Roberson

Science is all about asking questions. Why do some microbes make us sick? How do birds find their way when they migrate? When and where will the next big earthquake hit? But you can't just ask questions; you've also got to look for answers, and that usually calls for some ingenuity. You've got to design an experiment and gather data, or find something, measure it, study it, and test it. Maybe you're looking for an animal in the deep sea, but no one knows exactly where it lives. Maybe you need to gather data from the bottom of the ocean above the Arctic Circle, where it's icy most of the year and dark all day in winter. Or maybe you're trying to figure out how to locate buried land mines so they can be safely deactivated.

A giant Gambian pouched rat is trained to look for land mines. (Apopo)

In the quest for knowledge, scientists often build a better telescope, write a new computer program, or invent a radio-controlled robot. In some cases, however, the best new technology turns out to be an animal. Sperm whales, narwhals, bees, giant Gambian pouched rats, and many other animals are being "harnessed" in fascinating ways by scientists to gather information and help answer questions about the world around us.

Sperm Whales: Bird Dogs in the Hunt for Giant Squid
On September 28, 2005, the giant squid (genus Architeuthis) had its 15 minutes of fame on the evening news. Two Japanese scientists, Tsunemi Kubodera and Kyoichi Mori, announced that they had at long last succeeded where many had failed before: They captured the first photographs of the giant squid in its natural habitat, 900 meters under the sea, off the Ogasawara Islands in the North Pacific.

Scientists who study cephalopods (squid, octopus, and cuttlefish) have long known about giant squid, which occasionally come aboard ships in fishing nets, or wash up dead on beaches. These giant invertebrates have eight arms and two long tentacles, and can be as long as 18 meters (about 59 feet). They are believed to be common in oceans worldwide, but before Kubodera and Mori's announcement, no one had ever seen or photographed one in its natural underwater habitat—and not for lack of trying. The problem is that oceans are so vast, and giant squid live deep underwater, between 400 and 1,000 meters below the surface.

Clyde Roper, an emeritus zoologist at the Smithsonian Institution's National Museum of Natural History, has spent the last decade pondering the giant squid and trying to find it. From 1996 to 1999, he led three expeditions to search for the elusive animal. Scientists and technicians from America and New Zealand joined forces for the effort. The big question: Where to look?

For guidance, Roper turned to a more familiar ocean creature—the sperm whale (Physeter catodon). "Giant squid are the principal diet of sperm whales," says Roper, who estimates that a sperm whale might eat three or four giant squid a week. Most sperm whales have circular scars all over their squarish snouts from the huge suckers on giant squid tentacles, and the whales' stomachs are often full of undigested giant squid beaks.

The team did some research about sperm whale distribution, the contents of sperm whales' stomachs, and the frequency of giant squid strandings worldwide to choose the locations of their expeditions: off South Island, New Zealand, and in the Azores, islands in the North Atlantic Ocean about 1,300 kilometers west of Portugal. They planned to use manned and unmanned submersibles, and cameras lowered on baited cables to try to photograph the giant squid.

When Roper had a conversation with Greg Marshall, a cameraman for National Geographic, another idea emerged. Marshall had extensive experience in mounting underwater video cameras called "Crittercams" on shallow-water marine animals such as seals and sharks. "We thought it would be really interesting," Roper said, "to put the Crittercam on the only creature that had any knowledge of where giant squid lived, and that, of course, was the sperm whale." The Crittercam consisted of a video camera, light-emitting diodes (LEDs), and depth- and sound-recording capabilities, all housed in a tough waterproof covering.

The next challenge was figuring out how to attach the Crittercam to the whales' heads. "We settled on a huge, huge suction cup," says Roper. "The idea was to paddle up to a sperm whale in an inflatable kayak and place the suction cup on its head and evacuate the air from the cup. As incredible and scary as that seems, it actually worked."

The Crittercam and suction cup were held together with a magnesium wire that was designed to dissolve in sea water after one or two hours. The camera then floated to the surface and sent out radio signals so the crew could pick it up. The suction cups eventually slid down the back of the whale and dropped off.

Eight sperm whales were outfitted with Crittercams. Most whales showed little or no reaction when the camera was attached, but one whale decided to dive just after the Crittercam was placed. The whale's flukes came out of the water underneath the kayak and lifted it up out of the water. "I was watching from the ship," Roper says, "and I saw these bodies go catapulting out of the kayak—two paddlers and a cameraman." Luckily, no one was hurt, although an $80,000 movie camera bounced out of the kayak and went to the bottom of the sea. The camera was one of several being used to film the National Geographic special "Sea Monsters: Search for the Giant Squid."

The Crittercams were used on two expeditions—one in 1996 and one in 1997. Although they did not find a giant squid, Roper says the expeditions were a success because the Crittercams and other cameras gathered exquisite footage of other animals, including deep-sea organisms and schools of dolphins harassing sperm whales. He also describes an incident in which a whale dove down into the pitch-black depths, far out of reach of the sun's light. The Crittercam was not lighted, but it captured the faint sound of another sperm whale, far in the distance, emitting a "song" of clicks. The whale wearing the camera responded, and the two whales took turns clicking until the sounds were equal in volume, indicating that they were swimming side by side. "Who knows what the conversation was?" Roper says. "I like to think it was, 'Hey, have you seen any squid over there? None over here.' 'Well, there's plenty over here, come on over.' I still get goose bumps when I think and talk about that."

The Japanese scientists who photographed the giant squid used a camera on the end of a long cable. The camera was baited with shrimp and small squid. Even though sperm whales weren't carrying the cameras, they played a big role in that project, too. In their scientific paper, Kubodera and Mori referred to Roper's Crittercam project, then wrote, "We also used sperm whales . . . the most effective hunters of giant squid, as guides to target the specific locations and depths where large mesopelagic cephalopods (including Architeuthis) are most likely to occur." They analyzed data gathered by tagging and tracking sperm whales over several years and found that the whales appeared to hunt most frequently in a particular area and consistently dove to depths of 800 to 1,000 meters during the day and 400 to 500 meters at night. They placed their cameras accordingly.

Giant squid illustration
An illustration of the giant squid, circa 1874. (NOAA)

"Getting these images at this time is a fabulous accomplishment," Roper says, "and it represents not the end but really a new beginning in the search for trying to understand the giant squid in its natural habitat. So much is going on in the deep sea that we poor land-bound animals have little idea of."

Land-bound as we are, it often makes sense to enlist the help of sea creatures in our search for knowledge. And squid-hunting cephalopod scientists are not the only ones to do it.

Narwhals: Going Where No Human Has Gone Before
Physical oceanographers are engaged in a different sort of hunt, for data that will help them piece together the complicated and changing water circulation patterns in the world's oceans. Because many parts of the ocean are often inaccessible, ice-covered, or storm-tossed, oceanographers spend a lot of time thinking about ways to get those data.

The ocean is constantly in flux: Currents are driven by winds, the Earth's rotation, and by relative density. For example, the air cools surface waters at both of the Earth's poles. The water begins to freeze, leaving salt behind in the unfrozen water. Then, that cold, salty water, which is dense, sinks and moves toward the equator. The sinking of the water pulls warmer, less dense waters from lower latitudes up toward the poles, creating an enormous worldwide circulation. There are untold numbers of other, smaller circulation patterns at work all over the globe; many are yet to be fully studied.

Oceanographers are working to understand the ocean's circulation patterns in part so they can find out if the currents are changing in response to global warming. Changes in ocean circulation could have profound effects on global climate.

Craig Lee, a senior oceanographer at the Applied Physics Laboratory at the University of Washington, is studying how fresh water from melting icebergs and glaciers in the Arctic mixes with salty water coming up from the North Atlantic. As part of his work, he needs to collect data on temperature and salinity from the depths of Baffin Bay and the Davis Strait, bodies of water that are between Greenland and Canada's Baffin Island. "Making observations in the ocean is a very difficult undertaking," Lee says. "The traditional method is to run around in a ship, and you stop at a location and you lower an instrument in the water and bring it back up again. You're on a 300-foot research vessel with 40 to 60 people. It happens very slowly and you take a limited number of measurements."

To make matters more complicated, Baffin Bay and much of Davis Strait are above the Arctic Circle, and are dark all winter long. The water is partially ice-covered about nine months of the year, and almost completely ice-covered by the end of winter, effectively preventing research ships from working.

To get around some of these problems, Lee and other oceanographers use some instruments that they can leave in the water, either sitting on the sea floor or attached to floats and lines; these instruments can be monitored from a distance. There is also an underwater "glider" that moves around while collecting data, steered from the comfort of a scientist's office thousands of miles away.

One of the newest data collectors has actually been around for at least a million years—the narwhal (Monodon monoceros). For this effort, Lee has teamed up with Kristin Laidre, a narwhal expert and post-doctoral research scientist at the Greenland Institute of Natural Resources in Nuuk, Greenland. Marine zoologists have been using satellite tags to study the animals for about ten years. A tag, which is smaller than a deck of cards, is pinned to a whale's dorsal ridge, where it typically remains for eight to 12 months. Whenever the whale surfaces, the tag beams data to satellites. "Everything we know about narwhals—their ecology, behavior, movement—is because of these satellite telemetry studies," Laidre says. "They've worked really well."

This year, for the first time, the narwhals will be collecting data not about themselves, but about temperatures at different depths in the bay. Laidre says, "Most of the narwhals in the Canadian High Arctic go out into central Baffin Bay during the winter and spend five to six months out there, diving to the bottom repeatedly all day long. These whales are doing exactly what we want them to do in terms of deep-ocean sampling."

This past August, Laidre and her colleagues caught eight narwhals off the coast of Baffin Island and fitted them with satellite tags containing instruments that will measure ocean temperatures. Using narwhals has several potential advantages. For one thing, the tags are relatively cheap. At several thousand dollars each, they easily beat a research vessel that might cost between $5,000 and $10,000 a day to operate. "There are few oceanographic studies that send out ships into ice-covered seas for six months," Laidre says. "These whales are really convenient because they do it for you. You can sit in your office and collect data; you don't have to be in the field." The narwhals also travel to great depths: Previous satellite telemetry has shown they routinely dive 1,500 meters, and Laidre believes they are capable of diving between 1,500 and 2,000 meters. The "gliders" can only sample at 1,000 meters and shallower.

Of course, there are potential drawbacks too. "You have no control over where the whale goes, but if you tag enough whales, presumably you get a reasonable distribution of data," Lee says. While this is true, Laidre notes that narwhals have remarkable site fidelity: Individual groups of whales return to the same places in Baffin Bay year after year, so she has a pretty good idea of where the data will be gathered.

Overall, Lee is optimistic about the project. "Given the difficulty of making measurements in these environments, there's a lot to be said for having multiple approaches to the problem," he says.

This is not the first time that marine mammals or fish have been used to collect data for physical oceanographers. Other data-collecting animals include elephant seals (Mirounga angustirostris), ringed seals (Phoca hispida), white whales (Delphinapterus leucas), and bluefin tuna (Thunnus thynnus).

Nor are sea animals limited to sampling for physical data such as temperature and salinity. Laidre and one of her colleagues, Mads Peter Heide-Jørgensen, a senior scientist at the Greenland Institute of Natural Resources, have started work on a project to have bowhead whales (Balaena mysticetus) sample for chlorophyll in areas where the whales feed. Measuring chlorophyll is one way to measure productivity (the concentration of plant and animal life) in different parts of the ocean, because where there are plants, there will also be higher life forms feeding on the plants.

Bees and Rats: Sniffing out Bombs and Bacteria
While some scientists are using animals to collect data, others are looking to harness animals' abilities in other ways. Dogs, for example, can use their exquisite sense of smell to locate bombs, drugs, and dead bodies. While dogs' noses put ours to shame, their highly developed sense of smell is not unusual in the animal kingdom. Bees also have incredibly sensitive olfactory systems that guide them to blooming plants, even from miles away. Scientists in Montana are studying bees and finding ways to use them to locate old land mines.

Bees sniff out mines at the Department of Energy's Sandia National Laboratories. (Randy Montoya)

Land mines in war-torn countries kill and maim thousands of people every year, and take up valuable land that could be put to more productive uses. Many people are very motivated to clear out old minefields, but it's obviously a tricky job. How do you locate each mine so you can safely destroy it? Dogs have been used to sniff out mines, but it takes a lot of time and money to train them, and unfortunately, they are heavy enough to trigger mines. Manufactured chemical sensors are not sensitive enough to detect the vapors from explosives. Metal detectors work only on metal land mines, not on the newer plastic ones. And flailing—beating the ground with heavy chains attached to armored vehicles—is a method used to detonate minefields, but it tends to leave a certain percentage of them unexploded.

This is where bees come in. They can be trained to fly to particular odors, including odors given off by explosives in buried land mines. Jerry Bromenshenk, a professor of biological sciences at the University of Montana in Missoula, is one of a team of scientists from his university as well as Montana State University and the National Oceanic & Atmospheric Administration who have been working on a bee-training project for about six years. He explains, "In general, it's the same type of operative conditioning or Pavlovian response that has been used with other types of animals. The animal associates the odor you present with some type of reward, and the reward in this case is a . . . syrup solution." Bees take only one to three days to train and are available worldwide. The team works with Apis melifera, a honeybee that originated in Afghanistan, but now lives on every continent expect Antarctica.

The team doesn't train individual bees. "We train a large segment of the forager force," says Bromenshenk. "Our system sets up so that they become self-recruiting. Although the average bee has only ten to 12 good foraging days in it, whatever number of bees we lose on any day is made up with new bees coming into the foraging force."

Of course, training the bees to fly to spots where they smell explosives is only half the job. There has to be a good way to track the bees' movements from a distance so that people don't have to walk around on the minefield to map where the bees are going. The team has had some success with light detection and ranging, also called lidar, a technology that uses light in much the same way that radar uses radio waves. Laser beams pulse out at regular intervals, and the beams that hit bees bounce back to a detector.

In the summer of 2003, the team traveled to Missouri and conducted a field test at a minefield where various types of land mines had been buried (all the fuses had been removed from the mines). The data collected were used to make a map of bee concentrations, which correlated very closely with a map of the buried land mines. Not only did the bees find most of the land mines, they also found a spot on the field where there was no land mine but the soil was contaminated with a small amount of explosive powder.

Although lidar works well, it can be dangerous to humans, who can damage their eyes if they look at the light. "Our goal is a portable, eye-safe, battery-powered system," says Bromenshenk, who adds that a large expensive system like lidar, which requires trained technicians to operate, wouldn't be practical in many of the developing countries that need the technology. The team is currently working on a new bee-detecting system that is smaller and less expensive than lidar; they hope to see their work put to practical use in the next year or two. "You wouldn't simply replace all the traditional approaches with bees," he says, "but they would be used as a first-step survey because they can cover the areas so fast."

Neither bees nor dogs are able to find land mines that have not yet begun to leak explosives, but Bromenshenk says it might be possible to train bees to recognize some of the smells associated with the casing materials. "You should be able to train bees to find anything that has an odor, provided the odor is not repugnant to them," he says. For that reason, bees may be used in the future to sniff out not only leaking land mines, but also drug labs or dead bodies.

Another talented sniffer is also being trained to find land mines—the giant Gambian pouched rat (Cricetomys gambianus). A group of scientists from a Belgian organization called Apopo has trained these one-kilogram rodents to scratch at the ground where they smell explosives. In return, the rats are rewarded with a banana or peanut. In a test on a real minefield in Mozambique, a team of six rats found all 20 land mines. The rats, which take eight months to a year to train, are too lightweight to set off land mines, and are less expensive to keep and train than dogs.

Bizarre as it may sound, the scientists at Apopo are also training these rats to diagnose tuberculosis (TB). In a project funded by the World Bank, they have so far proven themselves to be as accurate as human technicians and quite a bit faster. Technicians take a sputum sample, culture it, and look at it under a microscope. The rats, on the other hand, run among Petri dishes of sputum samples. Every time a rat smells the TB bacteria, it scratches in front of the dish for a reward. In one trial, the rats had a 67 percent success rate, which is slightly more accurate than the standard laboratory method.

Who would have thought that rats could diagnose TB, or that bees could find land mines, or that whales could collect oceanographic data? It just goes to show that it pays to keep an open mind when pondering the mysteries of the universe, and that it's often a good idea to ask the animals for a little help.

—Mary-Russell Roberson is a writer living in Durham, North Carolina.

ZooGoer 35(1) 2006. Copyright 2006 Friends of the National Zoo. All rights reserved.

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