BigDog, Cheetah, WildCat and Atlas have joined Google's growing robot menagerie.
Google confirmed late last week it had completed the acquisition of Boston Dynamics, an engineering company that has designed mobile research robots for the Pentagon. The company has gained an international reputation for machines that walk with an uncanny sense of balance and even - cheetah-like - run faster than the fastest humans.
It is the eighth robotics company that Google has acquired in the past six months. Executives at the internet giant are circumspect about what exactly they plan to do with their robot collection.
But Boston Dynamics and its animal-kingdom-themed machines bring significant cachet to Google's robotic efforts, which are being led by Andy Rubin, the Google executive who spearheaded the development of Android, the world's most widely used smartphone software.
The deal is also the clearest indication yet that Google is intent on building a new class of autonomous systems that might do anything from warehouse work to package delivery and even elder care.
Boston Dynamics was founded in 1992 by Marc Raibert, a former professor at the Massachusetts Institute of Technology.
It has not sold robots commercially, but has pushed the limits of mobile and off-road robotics technology, mostly for Pentagon clients such as the Defence Advanced Research Projects Agency. Early on, the company also did consulting work for Sony on consumer robots such as the Aibo robotic dog.
Boston Dynamics' walking robots have a reputation for being extraordinarily agile, able to walk over rough terrain and handle surfaces that in some cases are challenging even for humans.
A video of one of its robots named BigDog shows a noisy, gas-powered, four-legged, walking robot that climbs hills, travels through snow, skitters precariously on ice and even manages to stay upright in response to a well-placed human kick. BigDog development started in 2003 in partnership with the British robot maker Foster-Miller, NASA's Jet Propulsion Laboratory and Harvard.
Google's other robotics acquisitions include companies in the US and Japan that have pioneered a range of technologies including software for advanced robot arms, grasping technology and computer vision. Mr Rubin has also said that he is interested in advancing sensor technology.
Mr Rubin has called his robotics effort a "moon-shot", but has declined to describe specific products that might come from the project. But he has also said that he does not expect initial product development to go on for years, indicating that Google commercial robots of some nature could be available in the next several years.