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
Life: A Natural History of the First Four Billion Years of Life on Earth over a thousand public libraries in the United States alone. Life: A Natural History of the First Four Billion Years of Life on Earth Life: A Natural History of the First Four Billion Years of Life on Earth is a non-fiction book written by British paleontologist Richard A. Fortey. It was originally published in hardcover in Great Britain by HarperCollins Publishers, under the title Life: An Unauthorised Biography. Fortey used this book to explain how life has evolved over the last four billion years. He discusses evolution, biology, the origin of life, and paleontology. Under its various titles Fortey's book