Abstract:
Most marine snails of the families Muricidae and Thaididae, which make up the genera Murex, Thais, and Plicopurpura, produce in the hypobranchial gland (mucus gland) a viscous liquid secretion. The secretion contains, besides mucus and biologically active compounds, minute amounts of chromogens, which develop enzymatically and under the influence of light and oxygen into a purple pigment known as "Tyrian purple," "Royal purple," or "Shellfish purple." Throughout history, humans have used the pigment for various purposes. On the Pacific Coast of Mexico and Central America. for at least 500 y, the dyeing properties of the "snail's ink" have been known and the pigments used for ceremonial and funeral garments. Here, the muricid Plicopurpura pansa (Gould, 1853) is the most exploited, and rarely the thaid Thais kiosquiformis. T. kiosquiformis has to be killed to obtain a few drops of the secretion from the hypobranchial gland, in contrast to P. pansa, which can be "milked" periodically without harming the animal to obtain a few milliliters of mucus containing the "Tyrian purple" precursors, In contrast to the Mediterranean region, where the use of purple from marine snails has long been forgotten and the craft of dyeing today cannot exactly be reconstructed, in remote Pacific regions of Mexico (in the states of Oaxaca and Michoacan) and in the Indian community of the Borucas in Costa Rica, its use continues until the present day on a small scale and represents the survival of a knowledge of considerable antiquity. However, it is feared that this old tradition will be lost in the near future. The scarcity of the snails, the time, patience, and labor required for collecting them: and the great numbers of them required to dye a small piece of material are the main reasons why cheap, synthetic pigments are today used for dyeing traditional dresses.
