Animal of other animal species for food, both of domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species. Marine fish of many species are caught commercially for food. A smaller number of species are farmed commercially. Invertebrates including cephalopods, crustaceans, and bivalve or gastropod molluscs are hunted or farmed for food. Chickens, cattle, sheep, pigs and other animals are raised as livestock for meat across the world. Animal fibres such as wool are used to make textiles, while animal sinews have been used as lashings and bindings, and leather is widely used to make shoes and
The Call of the Wild on trust and love. Writing in the "Introduction" to the Modern Library edition of "The Call of the Wild", E. L. Doctorow says the theme is based on Darwin's concept of survival of the fittest. London places Buck in conflict with humans, in conflict with the other dogs, and in conflict with his environment—all of which he must challenge, survive, and conquer. Buck, a domesticated dog, must call on his atavistic hereditary traits to survive; he must learn to be wild to become wild, according to Tina Gianquitto. He learns that in a world where the "club and the fang"