A fascinating and useful handbook to both the science and science fiction of extraterrestrial life. Cohen and Stewart are amusing, opinionated, and expert guides. I found it a terrific and informative piece of work-nothing else like it!-Greg BearI loved it.-Larry Niven Ever wonder about what aliens could be like? The world authority is Jack Cohen, a professional biologist who has thought long and hard about the vast realm of possibilities. This is an engaging, swiftly moving study of alien biology, a subject with bounds and constraints these authors plumb with verve and intelligence.-Gregory BenfordA celebration of life off Earth. A hearteningly optimistic book, giving a much-needed antidote to the pessimism of astrobiologists who maintain that we are alone in the universe-a stance based on a very narrow view of what could constitute life. A triumph of speculative nonfiction.-Dougal Dixon, author ofAfter Man: A Zoology of the Future