There seem to be a number of complementary reasons behind illustrations of sea monsters or other exotic creatures in the field of cartography. For mapmakers the idea was:

• to liven up the image of the world with decorative features,
• to fill empty spaces with information,
• to draw attention to the vitality of the oceans and the variety of creatures living in them,
• to suggest that the oceans and uncharted lands could be sources of danger,
• to serve as the graphic memory of literature on the subject,
• to provide points of reference in a geography of the marvellous,
• to draw attention to the artistic talent of the cartographer, who could then sell his work at a higher price, depending on the quality and quantity of the illustrations.

Sea and land creatures

For historians, three representations of sea monsters are predominant in Renaissance cartography: Olaus Magnus‘s Carta Marina (1539); the Monstra Marina & Terrestria map (1544) by Sebastian Münster, partly inspired by Olaus Magnus; and the Islandia map by Abraham Ortelius, published in Theatrum Orbis Terrarum (1586) and inspired by the two previous works.

Gerardus Mercator was particularly influenced by Magnus’ Carta marina, which contained the largest, most varied and most comprehensive collection of sea monsters of the day.

Mercator’s terrestrial globe is illustrated with eleven sea monsters, seven of which were taken from Magnus’s Carta marina and two others from Gonzalo Fernandez de Oviedo‘s Historia general de las Indias (1535), a book that represented the very first images of animals in America. Mercator no doubt used both Magnus and Oviedo to demonstrate his ability to combine the most recent sources in a nutshell. In addition to the sea monsters he included one terrestrial animal.

The monsters in cartography provides a detailed roundup of Mercator’s sources and inspirations for the twelve sea monsters and opossum.