Hexaplex trunculus
Encyclopedia
Hexaplex trunculus is a medium-sized species
of sea snail
, a marine
gastropod mollusk in the family Muricidae
, the murex
shells or rock snails.
This species of sea snail is important historically because its hypobranchial gland secretes a mucus that the ancient Canaanites/Phoenicians used as a distinctive purple-blue indigo
dye
. One of the dye's main chemical ingredients is indigotin, and if left in the sun for a few minutes before becoming fast, its color turns to a blue indigo (like blue jeans).
and the Atlantic coasts of Europe
and Africa
, specifically Spain
, Portugal
, Morocco
, the Canary Islands
, Azores
.
This murex occurs in shallow, sublittoral
waters.
s. The shell is variable in sculpture and coloring with dark banding, in four varieties. The ribs sometimes develop thickenings or spines and give the shell a rough appearance.
in ancient times. The snail itself is still used as a valuable food source in Portugal
.
, where large quantities of the shells have been recovered from inside ancient live storage chambers that were used for harvesting. Allegedly, 10-12,000 murex were needed to produce one gram of dye. The dye was highly prized in ancient times. Sometimes known as royal blue, it was prohibitively expensive and was only used by the highest ranking aristocracy.
A similar dye, Tyrian purple
, which is purple-red in color, was made from a related species of marine snail, Murex brandaris. This dye (alternatively known as imperial purple, see purple
) was also prohibitively expensive.
The Hebrew Bible
mentions a specific blue dye, called Tekhelet
for use in the Priestly garments as well in the layman's tzitzit
, the formal tassels or fringes of clothing, which some believe refers to the indigo dye from the Hexaplex trunculus when kept in the sun.
Similarly, the Hebrew Bible also mentions a specific purple dye, called argaman ( ʔaʁɡaˈman), which refers to the purple color this same dye produces when kept in the shade.
That is, research by Otto Elsner (Shenker College of Fibers, Ramat Gan, Israel
) and Ehud Spaneir (University of Haifa
, Haifa
, Israel) showed that by performing what is commonly referred to as "vat dyeing" based on the dyestuff from the trunculus, they could achieve colors varying from blue to purple depending on exposure to the sun when the dye solution was in its leuco (reduced) state. This phenomenon was attributed to the dyestuff being composed of indigo, mono-bromo-indigo and di-bromo-indigo. DiBromo-Indigo presents itself as purple whereas Indigo is blue. It was demonstrated that when the reduced solution of trunculus dye is exposed to sunlight, the UV-rays from the sun act to break the bromine bonds such that when oxidation occurs following the removal of the dyed fabric from the solution, pure indigo bonds to the wool, while the bromine atoms are left in the vat.
This feature of final color varying according to exposure to the sun was indeed known by the ancients, as noted in the writings of Vitruvius
(1 c. BCE), “Purple exceeds all colors in costliness and superiority of its delightful effect. It is obtained from a marine shellfish. ...It has not the same shade in all the places where it is found, but is naturally qualified by the course of the sun”.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusk in the family Muricidae
Muricidae
Muricidae, common name murex snails or rock snails, is a large and varied taxonomic family of small to large predatory sea snails. With approximately 1,600 living species the Muricidae represent almost 10% of the Neogastropoda. Additionally, 1,200 fossil species have been recognised...
, the murex
Murex
Murex is a genus of medium to large sized predatory tropical sea snails. These are carnivorous marine gastropod molluscs in the family Muricidae, commonly calle "murexes" or "rock snails"...
shells or rock snails.
This species of sea snail is important historically because its hypobranchial gland secretes a mucus that the ancient Canaanites/Phoenicians used as a distinctive purple-blue indigo
Indigo
Indigo is a color named after the purple dye derived from the plant Indigofera tinctoria and related species. The color is placed on the electromagnetic spectrum between about 420 and 450 nm in wavelength, placing it between blue and violet...
dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
. One of the dye's main chemical ingredients is indigotin, and if left in the sun for a few minutes before becoming fast, its color turns to a blue indigo (like blue jeans).
Distribution
This species lives in the Mediterranean SeaMediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
and the Atlantic coasts of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, specifically Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
, Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
.
This murex occurs in shallow, sublittoral
Littoral
The littoral zone is that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to...
waters.
Shell description
Hexaplex trunculus has a broadly conical shell about 4 to 10 cm long. It has a rather high spire with seven angulated whorlWhorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
s. The shell is variable in sculpture and coloring with dark banding, in four varieties. The ribs sometimes develop thickenings or spines and give the shell a rough appearance.
Human use
Secretions from this species of snail were used as dyeDye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
in ancient times. The snail itself is still used as a valuable food source in Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
.
As ancient dye
The ancient method for mass-producing purple-blue dye from Hexaplex trunculus has not yet been successfully reproduced (because the purplish hue degrades too quickly, resulting in blue only). Nonetheless the use of this species in dyeing "purple-blue" has been confirmed in the archeology of PhoeniciaPhoenicia
Phoenicia , was an ancient civilization in Canaan which covered most of the western, coastal part of the Fertile Crescent. Several major Phoenician cities were built on the coastline of the Mediterranean. It was an enterprising maritime trading culture that spread across the Mediterranean from 1550...
, where large quantities of the shells have been recovered from inside ancient live storage chambers that were used for harvesting. Allegedly, 10-12,000 murex were needed to produce one gram of dye. The dye was highly prized in ancient times. Sometimes known as royal blue, it was prohibitively expensive and was only used by the highest ranking aristocracy.
A similar dye, Tyrian purple
Tyrian purple
Tyrian purple , also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye, which is extracted from sea snails, and which was possibly first produced by the ancient Phoenicians...
, which is purple-red in color, was made from a related species of marine snail, Murex brandaris. This dye (alternatively known as imperial purple, see purple
Purple
Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade....
) was also prohibitively expensive.
As dye in Judaism
Hebrew Bible
The Hebrew Bible is a term used by biblical scholars outside of Judaism to refer to the Tanakh , a canonical collection of Jewish texts, and the common textual antecedent of the several canonical editions of the Christian Old Testament...
mentions a specific blue dye, called Tekhelet
Tekhelet
Tekhelet, , Tekheleth, Techelet or Techeiles is a blue dye mentioned 50 times in the Hebrew Bible and translated by the Septuagint as hyakinthinos . Its uses include the clothing of the High Priest, the tapestries in the Tabernacle, and the tassels to be affixed to the corners of one's garments...
for use in the Priestly garments as well in the layman's tzitzit
Tzitzit
The Hebrew noun tzitzit is the name for specially knotted ritual fringes worn by observant Jews. Tzitzit are attached to the four corners of the tallit and tallit katan.-Etymology:The word may derive from the semitic root N-TZ-H...
, the formal tassels or fringes of clothing, which some believe refers to the indigo dye from the Hexaplex trunculus when kept in the sun.
Similarly, the Hebrew Bible also mentions a specific purple dye, called argaman ( ʔaʁɡaˈman), which refers to the purple color this same dye produces when kept in the shade.
That is, research by Otto Elsner (Shenker College of Fibers, Ramat Gan, Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
) and Ehud Spaneir (University of Haifa
University of Haifa
The University of Haifa is a university in Haifa, Israel.The University of Haifa was founded in 1963 by Haifa mayor Abba Hushi, to operate under the academic auspices of the Hebrew University of Jerusalem....
, Haifa
Haifa
Haifa is the largest city in northern Israel, and the third-largest city in the country, with a population of over 268,000. Another 300,000 people live in towns directly adjacent to the city including the cities of the Krayot, as well as, Tirat Carmel, Daliyat al-Karmel and Nesher...
, Israel) showed that by performing what is commonly referred to as "vat dyeing" based on the dyestuff from the trunculus, they could achieve colors varying from blue to purple depending on exposure to the sun when the dye solution was in its leuco (reduced) state. This phenomenon was attributed to the dyestuff being composed of indigo, mono-bromo-indigo and di-bromo-indigo. DiBromo-Indigo presents itself as purple whereas Indigo is blue. It was demonstrated that when the reduced solution of trunculus dye is exposed to sunlight, the UV-rays from the sun act to break the bromine bonds such that when oxidation occurs following the removal of the dyed fabric from the solution, pure indigo bonds to the wool, while the bromine atoms are left in the vat.
This feature of final color varying according to exposure to the sun was indeed known by the ancients, as noted in the writings of Vitruvius
Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....
(1 c. BCE), “Purple exceeds all colors in costliness and superiority of its delightful effect. It is obtained from a marine shellfish. ...It has not the same shade in all the places where it is found, but is naturally qualified by the course of the sun”.
Further reading
- Radwin G. E. & D'Attilio A. (1986) Murex shells of the world. An illustrated guide to the Muricidae. Stanford University PressStanford University PressThe Stanford University Press is the publishing house of Stanford University. In 1892, an independent publishing company was established at the university. The first use of the name "Stanford University Press" in a book's imprinting occurred in 1895...
, Stanford, x + pp. 1–284 incl 192 figs. + 32 pls.