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Anatomy of a Web(bed) Legend

Virtual Frog Still Making a Splash After 10 Years on the Web

June 8, 2004


Fluffy, the virtual frog

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 tenth 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 Web site allows users to virtually dissect a frog without all that smelly formaldehyde of high school science class. While the frog 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 has 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 email from around the world, mainly from teachers who use the site in their classes,” said Bill Johnston, currently head of the Department of Energy’s Energy Sciences Network (ESnet), which is managed by Berkeley Lab.

Johnston and other members of the former Imaging Technologies Group, now part of the 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, leading 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 LBNL’s work in developing software to create visual renderings of sets of diagnostic cross-section images used in medicine, allowing scientists to create 3D renderings from 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).

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, UC approved the 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 LBNL’s research MRI machine to create 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. “It just would not work.”

Anat Biegon had a cryotome machine on the University of California at 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” at the Web site 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, 3D 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 Web sites” lists popular at the time. And because many people were still using 9,600 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 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, 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 Jeopardy TV game show.

In a case of what is old becoming new again, the compression techniques that allowed images to display quickly 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.”

About Berkeley Lab

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 16 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit