Little is known about his life. Aristotle was born in the city of Stagira in Northern Greece. His father, Nicomachus, died when Aristotle was a child, and he was brought up by a guardian. At seventeen or eighteen years of age he joined Plato's Academy in Athens and remained there until the age of thirty-seven (c. 347 BC). Shortly after Plato died, Aristotle left Athens and, at the request of Philip II of Macedon, tutored Alexander the Great beginning in 343 BC.[ He established a library in the Lyceum which helped him to produce many of his hundreds of books on papyrus scrolls. Though Aristotle wrote many elegant treatises and dialogues for publication, only around a third of his original output has survived, none of it intended for publication. ... Aristotle's views profoundly shaped medieval scholarship. The influence of physical science extended from Late Antiquity and the Early Middle Ages into the Renaissance, and were not replaced systematically until the Enlightenment and theories such as classical mechanics were developed. - [Wikipedia]

Aristotle teaching his students about the nature of animals. From a manuscript copy of De animalibus by Aristotle.

The text of interest here, De animalibus (On animals, also known as Historia Animalium, The History of Animals), is divided into 10 books (the tenth book is probably not actually by Aristotle). Most of Aristotle's publish texts have been lost; De animalibus was not one his finished, published works, but a collection of notes and teaching materials. The text became available (in Arabic) to European scholars around 1085, with the conquest of the Moorish kingdom of Toledo (Spain). The Arabic translation comprises treatises 1–10 of the Kitab al-Hayawan (The Book of Animals). The Arabic versions of Aristotle texts were translated into Latin in the thirteenth century by Michael Scot. Albertus Magnus commented extensively on Aristotle, and added his own zoological observations and an encyclopedia of animals based on Liber de natura rerum, a thirteenth century encylopedia by Thomas of Cantimpré.

Unlike later works by authors such as Pliny the Elder and Lucan, De animalibus does not often go into details of the characteristics of individual animal species; rather, Aristotle discusses categories of animals, and describes the attributes of those categories. Where he does describe individual species it is as examples of the category. Aristotle also relies more on observation instead of what he had heard from others, and he rejects some of the received wisdom as fanciful and fiction. The animals are not moralized or given meanings or value judgements.

Only a few of Aristotle's animal descriptions are directly used in medieval animal texts, though indirect references via later authors (Pliny, Lucan and others) are more common.