Salmon run plankton. At this point the baby salmon are called "fry". At the end of the summer the fry develop into juvenile fish called "parr". Parr feed on small invertebrates and are camouflaged with a pattern of spots and vertical bars. They remain in this stage for up to three years. As they approach the time when they are ready to migrate out to the sea the parr lose their camouflage bars and undergo a process of physiological changes which allows them to survive the shift from freshwater to saltwater. At this point salmon are called "smolt". Smolt spend time in
The Salmon of Doubt six is a better kind of number." The book as published is divided into two main sections: "Life, the Universe and Everything", which utilizes fiction, essays and interviews with Adams, and "The Salmon of Doubt", which presents the most complete version of the novel as Adams left it. The first section is then subdivided into three: "Life" touches upon Adams' own life, "The Universe" covers Adams' views of reality and "Everything", which is more wide open and includes the original version of the Hitchhiker's short story "Young Zaphod Plays It Safe". The UK edition includes an introduction by Stephen Fry,