Salmon divergence. Salmon eggs are laid in freshwater streams typically at high latitudes. The eggs hatch into alevin or sac fry. The fry quickly develop into parr with camouflaging vertical stripes. The parr stay for six months to three years in their natal stream before becoming smolts, which are distinguished by their bright, silvery colour with scales that are easily rubbed off. Only 10% of all salmon eggs are estimated to survive to this stage. The smolt body chemistry changes, allowing them to live in salt water. While a few species of salmon remain in fresh water throughout their life cycle,
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 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 has become a best-seller; according to WorldCat, it is in