BERKELEY, CA — In the wild, a frog may live to 10 years, assuming it survives tadpolehood and doesn't get eaten by a bird or a fish or some other creature. On the web, though, a "virtual" frog named Fluffy has easily notched its 10th year, despite millions of dissections.

Launched in June 1994 by the U.S. Department of Energy's Lawrence Berkeley National Laboratory, the Virtual Frog Dissection Kit website allows users to dissect a frog without all that smelly formaldehyde of high school science class. While it's the frog that has been accessed more than 15 million times by English-speaking users, 13 percent of those visiting the site are dissecting either la rana (Spanish), der Frosch (German), la Grenouille (French), a Râ (Portuguese), la Rana (Italian), zaba (Czech), or de kikker (Dutch).

The Virtual Frog site can be found at http://dsd.lbl.gov/ITG.hm.pg.docs/Whole.Frog/Whole.Frog.html, and has already been found by users in more than 130 countries.

"We know it's still being used because whenever the server goes down, we get a lot of e-mail from around the world, mainly from teachers who use the site in their classes," said Bill Johnston, currently head of the DOE's Energy Sciences Network (ESnet), which is managed by Berkeley Lab.

Johnston and other members of the former Imaging Technologies Group, now part of Berkeley Lab's Distributed Systems Department, developed the Virtual Frog. While the Virtual Frog has remained virtually unchanged over the past decade, the research behind the site has advanced by leaps and bounds and has led to Berkeley Lab's prominent role in the development of Grid technologies.

"The Virtual Frog was a direct result of our early work in wide-area distributed computing and visualization," Johnston said. "And this has led directly to our involvement in developing collaborative technologies and Grid applications."

The frog was originally spawned by Berkeley Lab's work in developing software to create visual renderings of sets of diagnostic cross-sectional images used in medicine, allowing scientists to create 3-D renderings from magnetic resonance imaging (MRI) data. This capability was first demonstrated at the 1991 Supercomputing Conference in Albuquerque, the first conference in that series to have a high-speed network connection (45 Mb/s, or 45 million bytes per second).

Once the software was developed, Johnston said, he began to think about what to do with it. The line of thinking led to DOE's education programs, and then to secondary schools. "Obviously, the choice was to create a frog."

The first step was to obtain a specimen, which was purchased at a Berkeley pet shop and then euthanized following a strict University of California-approved protocol for handling animals for experiments. Once the amphibian was dead, lab assistant Katie Brennan brought it out to the team with her hands clasped around the creature. She opened them slowly and declared, "Voila — Fluffy!" A star was named.

Next, the challenge was to use the Lab's MRI machine to create the layered images. "No matter what they did, the images came out mushy," Johnston said. The cause turned out to be the dark green spots on the frog's back. Containing iron oxide pigment, the spots set up magnetic fields that wreaked havoc on the imaging system.

Anat Biegon had a cryotome machine on the UC Berkeley campus that used a swinging diamond blade to make extremely thin slices of tissue. Fluffy was encased in a block of frozen thermosetting plastic and reduced to 130 slices, each one-tenth of a millimeter thick. After each slice was removed, the remaining portion of the frog was photographed (see "Available Image Data" on the Virtual Frog website for the photographs).

Each of the photos was then digitized, and UC Berkeley biology student Craig Logan carried out the laborious task of segmentation — using a pen to outline critical organs or systems on each of the 130 slides. Wing Nip, a computer science student at San Francisco State University, worked with Logan on digitizing the images.

"That is what allows you to manipulate 11 different anatomical systems," said David Robertson, who developed the Virtual Frog Dissection Kit that makes the whole thing work. "This was one of the first, if not the first, 3-D rendering applications on the web."

Of course, as Robertson admits, there wasn't a whole lot of anything on the web in those days. As a result, the frog regularly made the "top 10 websites" lists popular at the time. And because many people were still using 9600-baud modems, Robertson had compressed the images to make them more easily accessible.

With no search engines and minimal marketing, the Virtual Frog leapt to prominence by word of mouth — and by way of a holiday greeting card. In the mid-1990s, the Lab Director's Christmas card featured Fluffy's skeleton, adorned with a ribbon and bow at the neck. "The usage went up exponentially," Johnston said.

"It rapidly shot up to 1.5 million hits a year," Robertson added. "And it continues to get up to 40,000 hits a day from 130 countries."

Site visits finally leveled off in 2002, a year after DOE's Web Council honored the Virtual Frog as representative of DOE's best web resources, saluting its "ability to provide the public with valuable content in a user-friendly format." The site has also been recognized by the U.S. Department of Education, the BBC, and numerous magazines and web publications.

And it officially entered pop culture in November 1999 when the dissection kit was featured in the "Frog Stuff" category on the TV game show "Jeopardy."

In a case of what is old becoming new again, the compression techniques that allowed quick display of images over a 9600-baud modem now enable people with "smart phones" to call up the Virtual Frog using the browsers on the phones, which typically have low-bandwidth wireless connections.

"I don't think any of us realized how popular — and how enduring — the site would become," Johnston said. "What started as something of an experiment has become an institution."

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, CA. It conducts unclassified scientific research and is managed by the University of California. Visit our website at http://www.lbl.gov.

Additional information

• More on the Virtual Frog Dissection Kit