Lab rats have a lot of wild company lately.
Vampire bats, electric eels and armadillos are just some of the creatures being studied for their unique characteristics to further science and help find cures.
"It's important to look beyond the mouse," said Liz Pennisi, a writer for Science magazine. "Widening the scope of which animals you study can help you understand evolution and the diversity of life."
Animal rights activists have long claimed animal research is cruel and unnecessary. And while some animals used for scientific studies seem exotic, they become "a flavor of the month" for researchers, said Troy Siedle, science policy advisor for People for the Ethical Treatment of Animals.
Scientists, on the other hand, believe that studying a variety of animals is critical for breaking new biomedical ground.
"Exploring a wider range of animals simply gives us a bigger tool box from which to draw from as we encounter problems that people or other animals have," Dr. Thomas Kunz, director for the center for ecology and conservation biology at Boston University, said. "If you're trying to fix your plumbing and you only have one wrench, you're going to be limited."
The majority of animal research is still performed on "model animals" such as rodents, but widening the scope has proved successful for many researchers.
In one recent medical breakthrough, scientists in Australia found that a substance in the saliva of vampire bats could provide a new treatment for strokes.
"When the vampire bat bites its victim, it secretes this powerful clot-dissolving substance so that the victim's blood will keep flowing, allowing the bat to feed," Dr. Robert Medcalf of the Monash University Department of Medicine at Box Hill Hospital in Victoria, Australia, told The Associated Press.
That same substance might someday be given to stroke victims to dissolve clots and thereby limit brain damage, he said.
Learning how and why animals age as they do is one of the hottest topics in biomedical research, and bats are also helpful in this area of study, according to Kunz.
"[Bats] are long-living for their body size. They're the size of a thumb and live up to 37 years," said Kunz. "Studying an animal that lives long has advantages such as seeing the effects of something over a long period of time or studying the effects of aging."
Approximately 90 percent of animals used in scientific research are rodents, according to the North Carolina Association for Biomedical Research. But Pennisi said, "a lot of people choose non-traditional model organisms as their new model because of what that organism offers them."
For example, the armadillo is the only animal besides primates and mice in which the leprosy bacillus grows. Scientists have been able to use the animal to test a vaccine for people suffering from the disease.
And researchers at the University of California San Francisco have been able to cure infertile flies by injecting a particular gene into them. The research may offer hope to men with low sperm counts.
Other unexpected creatures used for science include the horseshoe crabs, which have been studied to help human colorblindness; electric eels, used to study the human nervous system; and zebra fish, which are a favorite among researchers because it's possible to literally see what's going on inside the fish.
"A lot of people study fish development because they're transparent," said Pennisi. "That's something you just can't do with a chicken. ... researchers pick the animal because of what it does and what principal you want to derive from it."
As for a certain species having characteristics of humans, Siedle countered that even studies done on human males are not effective for human females because they are too different.
"The same types of experiments carried out on mice and dogs are just being repeated on newer species," Siedle said. "Whether or not you'll see any payoff in human medicine is just a shot in the dark."