Purple snail

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Bolinus brandaris
Hexaplex trunculus

As Purpurschnecke to various marine referred snails from the family of whelks (Muricidae) from the secretions of a gland in the mantle cavity magenta dye can be obtained. This applies to numerous species of this family worldwide , but with the purple snail, the two species formerly known as Murex that live in the Mediterranean are mostly Hercules' club ( Bolinus brandaris ) and blunt prickly snail ( Hexaplex trunculus ) as well as the northern purple snail of the North Atlantic ( Nucella lapillus , formerly purpura lapillus ), sometimes also the species Stramonita haemastoma .


The species of the family of the porcupine snails (Muricidae), to which the purple snails belong, are mainly predatory , but sometimes also scavenger . They eat barnacles , other snails and mussels by breaking open, prying open or piercing the shell of the prey with their own shell edge. Not all spiked or purple snails can drill, including the Hercules club . Other species, including Blunt murex and the Nordic Purpurschnecke possess an accessory bore organ (ABO) on the sole of the foot, by means of which they dissolve lime and so by simultaneously rasps with the radula holes in shells of mussels, snails and barnacles can drill.

From the purple snail Hexaplex trunculus gained Purpurküpe .
Structural chemical formula of purple

Function of the purple secretion

Not to be confused with the ABO is the hypobranchial gland , which in purple snails is located in the ceiling of the respiratory cavity next to the rectum . This gland secretes a yellowish mucus containing choline esters , which paralyze the prey, relax its sphincter muscles and thus lead to the opening of the operculum or the clamshell halves. The secretion is also deposited when the snail is irritated, so it obviously also serves as a defense. This liquid, which must not be confused with the purple dye, only contains the dye precursors (chromogens) and only develops into the purple dye in sunlight or under the action of oxygen or both . At first the secretion turns green, then blue, finally purple and scarlet , giving off a nauseating, long-lasting odor.

The dye also forms in the absence of air in nitrogen or hydrogen , but not in the dark. You can extract the coloring substance from the powdered snails with alcohol and ether , and from the golden yellow solution the purple separates in the light as a granular crystalline powder, which is insoluble in water , alcohol and ether, but soluble in boiling aniline .

Cultural history

Purple snails were made long before the Phoenicians , around 1600 BC. Used for dyeing . Pliny the Elder (around 23–79) reports in his Naturalis historia ("Natural History") of the complicated manufacturing process . The sea snails had to be caught alive in fish traps , then the small glandular body was removed from the respiratory cavity. In order to obtain the whitish secretion contained therein, the glands were crushed, immersed in salt for three days and heated for ten days, but not boiled. That would have prevented the dye from developing. Under the action of light or oxygen or both, the purple dye developed rather rapidly, but as a developed dye it could not be absorbed onto the fiber. To do this, it had to be reduced to its leuco form. The fabric to be dyed was then immersed in the purple vat. All colored material comes out of the vat green, it is immediately immersed in fresh water and only in contact with the oxygen, if possible without exposure, does the purple variant appear. Finally, the soaked wool is washed well and left to dry in the sun.

1.5 grams of the dye could be obtained from 12,000 purple snails . To dye one kilogram of wool, 200 grams of dye were required, which corresponds to three kilograms of glandular juice. This high number, probably due to Paul Friedlaender (1857–1923), who clarified the chemical structure of the purple dye, is no longer confirmed by Israeli researchers. It has recently been found that 1 kg of wool, for example for a ruler's tunic , can be dyed with 10,000 snails.

Roman magistrates and senators wore their toga with a purple stripe, and the toga of Roman emperors and triumphators was also colored with purple. It was reserved for them.

Individual evidence

  1. Cleveland P. Hickman, Larry S. Robert, Allan Larson, Helen l'Anson, David J. Eisenhour: Zoologie . Translated from the English by Thomas Lazar. German adaptation by Wolf-Michael Weber. 13th edition, Pearson Studium, Germany, Munich 2008, 1347 pages, ISBN 978-3-8273-7265-9 , p. 510. Here also the German translation of the English expression ABO (accessory boring organ).
  2. a b Melbourne R. Carriker (1981): Shell penetration and feeding by naticacean and muricacean predatory gastropods: a synthesis . (PDF; 12.5 MB), In: Malacologia. 20 (2), pp. 403-422.
  3. H. Fouquet: Structure and reactions of natural chromogens of indogoid dyes in purple snails. (Dissertation) Saarbrücken 1970, p. 2, 13.
  4. G. Thomas Watters, Ohio State University: Digital Murex - Purpura Bruguiere, 1789 ( Memento of the original from July 19, 2010 in the Internet Archive ) Info: The @1@ 2Template: Webachiv / IABot / www.biosci.ohio-state.edu archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
  5. Marianne Guckelsberger, Purple murex Dye in Antiquity (University of Iceland 2013) pp. 8 to 12.
  6. purple on seilnacht.com, accessed on January 9, 2017th


Web links

Wiktionary: purple snail  - explanations of meanings, word origins, synonyms, translations