Until the latter half of the 19th Century it was possible for an individual to have a reasonable grasp of what, at the time, was known as natural philosopy. Since then, the body of scientific knowlege has exploded to such an extent that it is difficult for an individual to keep track of even one of the major disciplines of physics, mathematics, chemistry, biology, engineering and medicine. Optics itself has fragmented to such an extent that the American community feels that it requires two major learned societies to cover its needs and even that does not count ophthalmic opics and optometry. One result of this fragmentation is that some areas are of interest to different parts of the scientific commnity and are studied and developed independently and in completely different ways. One example of this is optical design which is firmly embedded within `physical optics' but at the same time has played a very important role in the development of a great many forms of animal life and is therefore equally firmly embedded within the biological sciences. In 1998, the Optical Group of the Institute of Physics organized a topical meeting in Bath for the European Optical Society on the subject of `Optical design in Nature'. This bought together biologists and physicists working in optics and included a large proportion of review papers in which broadly similar topics were covered by authorities from both disciplines. It enabled the biologists to be brought up to date with developments in optical technology and the physicists to learn of some of the fascinating and sophisticated optical systems that are to be found in Nature. It was widely felt that there is much to be gained from an interaction of this sort and that now is a particularly appropriate time to encourage it. Optical technology has developed and made available commercially a large number of items that are found in Nature; thin films, multilayer mirrors, graded index lenses, optical fibres, microlens arrays and subwavelength structures for example. In some cases the development has been inspired by Nature, in others it has been quite independent, but either way we are now in a stronger position than ever before to take advantage of Nature's solutions to her problems and apply them to our own. Futhermore, with the availability of high powered computers we are able not only to copy Nature's solutions but to copy Nature's methods of solving the problems. With genetic algorithms it is possible not only to mimic the processes of natural selection but also to accelerate them to the extent that they can realistically be used as tools for optical (and other) design. By devoting a special issue of the Journal of Optics A: Pure and Applied Optics to the topic of optical design in Nature, the European Optical Society and the Board of the Journal seek to highlight the subject and to invite those working in the area to use the pages of the journal to publish and exchange the results of their work. This issue contains a mixture of review and research articles, and the Editors would like to express their gratitude to the authors and their hope that this will stimulate further co-opertation between scientists of all backgrounds working in this fascinating and productive area of research. (Readers may also be intersted to know that a complementary series of articles, of a more popular nature, have been published in the magazine Photonics Science News 6 1/2.)