Classifying animals

In view of the close relationship between man and nature, since the antiquity people have been trying to know more about the living creatures and to class them. In the IV century b.C., Aristotle, the great Greek philosopher and scientist, began to class the known animals according to their physical features. Obviously, at that time very little was known on the internal anatomy of animals and such classification was therefore mainly based on the observation of their external features and was therefore rather approximate. The modern classification was developed by the Swedish scientist Linnaeus, who in the XVIII century introduced the concept of SPECIES (“group of individuals having the same characteristics and that, by mating, give birth to a fertile offspring, i.e. that can reproduce in its turn”). In addition, Linnaeus gave to each species two Latin names, the first indicating the genus, written with a capital initial, the second one indicating the species, written instead with a small initial, both in italic.
Very similar species are grouped into GENERA and likewise similar genera are grouped into the wider set of the FAMILY; families in their turn are grouped into ORDERS, orders into CLASSES, classes into TYPES or Phyla and finally types into KNGDOMS. There are five kingdoms: ANIMAL, VEGETAL, FUNGI, PROTISTA, MONERA.
Let’s classify the dog
To be clearer, let’s make an example: let’s take the dog and let’s class it like this. It belongs to the Animal kingdom and, since it owns a spine, it belongs to the type Chordata and subtype Vertebrates. Vertebrates in their turn are divided into five classes: Mammals, Birds, Reptiles, Amphibia and Fish. Dog is a Mammal, since its female breast-feeds its offspring; it belongs to the order Carnivores (the other orders being: Insectivores, Rodents, Cetaceans, Marsupials, etc.) and to the family Canidae. Some Canidae look very much like “man’s best friend”: for instance, the wolf, the fox and the jackal. All these are grouped into the genus Canis and distinguish themselves by the name of their species; in the case of the domestic dog, the name of the species is Canis familiaris.

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