Aristotle’s Work in Zoology and Meteorology
Although Aristotle’s work in zoology was not completely accurate, it was the greatest biological investigation of its time, and his work remained the ultimate authority for many centuries after his death. His knowledge of the anatomy of octopus, crustaceans, and many other marine invertebrates are remarkably accurate, and could only have been determined through first-hand dissection. He also described the embryological development of a chick, distinguished whales and dolphins from fish, described the social organization of bees, and observed that some sharks give birth to live young - his books on animals are filled with similar observations, some of which were not confirmed until many centuries later.
Aristotle’s classification system grouped together similar animals into genera, which is much broader than our present day genus, and distinguished species within those genera. His classification divided animals into two types: those with red blood and those without; these divisions correspond closely with our modern vertebrates and invertebrates. The “blooded” animals, corresponding to the vertebrates, included five genera: viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes, and whales (which Aristotle did not realize were mammals). The “bloodless” animals were classified as cephalopods (such as the octopus), crustaceans, insects (which included the spiders, scorpions, and centipedes, in addition to what we now define as insects), shelled animals (such as most mollusks and echinoderms), and "zoophytes," or "plant-animals," which supposedly resembled plants in their form - such as jellyfish and corals.
Aristotle believed that the universe was eternal; it never had a beginning or an end. This is where he differed most from medieval and modern scientists. Change was cyclical to Aristotle; although water might evaporate and rain down again, or rivers might come into existence and then perish, overall the world would never change.
Although Aristotle's pioneering Meteorologica was the first attempt to condense all of meterology into one cohesive subject, it is unlikely he greatly affected those communities whose weather forecasting combined memories of the local climate, dubious weather lore, and perhaps the opinion of an oracle. Nonetheless, Aristotle's great work served as the definitive Western meteorological textbook until scientific developments in the mid-15th century challenged many of his theories.
About the photo: This image is of a famous galaxy (M31) that appears within the constellation Andromeda. It is a spiral galaxy, like our own Milky Way. M31 is one of the farthest objects that can be seen with the naked eye, and was first described by 10th century Persian astronomer Al-Sufi. The knots of blue-white patches in the outer arms are newly formed stars.
image © Thomas V. Davis