Snails

In this episode of the I Can't Sleep Podcast, fall asleep learning about snails. Just thinking about how slow and tiny they are has me nodding off. Perhaps it will do the same for you tonight. Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast,

Where I read random articles from across the web to bore you to sleep with my soothing voice.

I'm your host,

Benjamin Boster.

Today's episode is from a Wikipedia article titled,

Snail.

A snail is a shelled gastropod.

The name is most often applied to land snails,

Terrestrial pulmonate gastropod mollusks.

However,

The common name snail is also used for most of the members of the molluscan class gastropoda that have a coiled shell that is large enough for the animal to retract completely into.

When the word snail is used in this most general sense,

It includes not just land snails,

But also numerous species of sea snails and freshwater snails.

Gastropods that naturally lack a shell or have only an internal shell are mostly called slugs,

And land snails that have only a very small shell that they cannot retract into are often called semi-slugs.

Snails have considerable human relevance,

Including as food items,

As pests,

And as vectors of diseases.

And their shells are used as decorative objects and are incorporated into jewelry.

The snail has also had some cultural significance,

Tending to be associated with lethargy.

The snail has also been used as a figure of speech in reference to slow-moving things.

The snail is similar in shape to the cochlea.

Snails that respire using a lung belong to the group pulmonata,

And as traditionally defined,

The pulmonata were found to be polyphletic in a molecular study per Yerger et al.

,

Dating from 2010.

But snails with gills also form a polyphletic group.

In other words,

Snails with lungs and snails with gills form a number of taxonomic groups that are not necessarily more closely related to each other than they are related to some other groups.

Both snails that have lungs and snails that have gills have diversified so widely over geological time that a few species with gills can be found on land and numerous species with lungs can be found in freshwater.

Even a few marine species have lungs.

Snails can be found in a very wide range of environments,

Including ditches,

Deserts,

And the abyssal depths of the sea.

Although land snails may be more familiar to laymen,

Marine snails constitute the majority of snail species and have much greater diversity and a greater biomass.

Numerous kinds of snail can also be found in freshwater.

Most snails have thousands of microscopic tooth-like structures located on a banded ribbon-like tongue called a radula.

The radula works like a file,

Ripping food into small pieces.

Many snails are herbivorous,

Eating plants or rasping algae from surfaces with their radulae,

Though a few land species and many marine species are omnivores or predatory carnivores.

Snails cannot absorb colored pigments when eating paper or cardboard,

So their feces are also colored.

Several species of the genus Acatina and related genera are known as giant African land snails.

Some grow to 15 inches from snout to tail and weigh one kilogram.

The largest living species of sea snail is Searing Serowinus.

Its shell can measure up to 90 centimeters in length and the whole animal with the shell can weigh up to 18 kilograms.

Recently,

The smallest land snails have been discovered in China and measure 0.

86 millimeters long.

The largest known land gastropod is the African giant snail,

The largest recorded specimen of which measured 39.

3 centimeters from snout to tail when fully extended with a shell length of 27.

3 centimeters in December 1978.

It weighed exactly 900 grams or two pounds.

Named G.

Geronimo,

This snail was owned by Christopher Hudson of Hove,

East Sussex,

UK and was collected in Sierra Leone in June 1976.

Snails are prostostomes,

That means during development in the gastrulation phase,

The blastopore forms the mouth first.

Cleavage in snails is spiral holoblastic patterning.

In spiral holoblastic cleavage,

The cleavage plane rotates each division and the cell divisions are complete.

Snails do not undergo metamorphosis after hatching.

Snails hatch in the form of small adults.

The only additional development they will undergo is to consume calcium to strengthen their shell.

Snails' eating habits vary widely,

With some being generalists and some being specialist feeders.

Snails feed at night.

They feed primarily on decaying organic matter.

Their diet also includes fungi,

Lichens,

Green foliage,

Worms,

Centipedes,

Insects,

Animal feces,

Carrion,

And other slugs.

Some snails feed on other snails too.

Castropods that lack a conspicuous shell are commonly called slugs rather than snails.

Some species of slug have a maroon brown shell,

Some have only an internal vestige that serves mainly as a calcium lactate repository,

And others have some to no shell at all.

Other than that,

There is little morphological difference between slugs and snails.

There are,

However,

Important differences in habitats and behavior.

A shell-less animal is much more maneuverable and compressible,

So even quite large land slugs can take advantage of habitats or retreats with very little space.

Retreats that would be inaccessible to similar size snail.

Slugs squeeze themselves into confined spaces,

Such as under loose bark on trees or under stone slabs.

Logs or wooden boards lie on the ground.

In such retreats,

They are in less danger from either predators or desiccation.

Those are often suitable places for laying their eggs.

Slugs as a group are far more monophyletic.

Scientifically speaking,

Slug is a term of convenience with little taxonomic significance.

The reduction or loss of the shell has evolved many times independently within several very different lineages of gastropods.

The various taxa of land and sea gastropods with slug morphology occur within numerous higher taxonomic groups of shelled species.

Such independent slug taxa are not in general closely related to one another.

Land snails are known as an agricultural and garden pest,

But some species are an edible delicacy and occasionally household pets.

In addition,

Their mucus can also be used for skincare products.

There are a variety of snail control measures that gardeners and farmers use in an attempt to reduce damage to valuable plants.

Traditional pesticides are still used,

As are many less toxic control options,

Such as concentrated garlic or wormwood solutions.

Copper metal is also a snail repellent,

And thus a copper band around the trunk of a tree will prevent snails from climbing up and reaching the foliage and fruit.

A layer of a dry,

Finely ground,

And scratchy substance such as diatomaceous earth can also deter snails.

The decollate snail will capture and eat garden snails,

And because of this it has sometimes been introduced as a biological pest control agent.

However,

This is not without problems,

As the decollate snail is just as likely to attack and devour other gastropods that may represent a valuable part of the native fauna of the region.

In French cuisine,

Edible snails are served,

For instance,

In escargot.

The practice of rearing snails for food is known as halliciculture.

For purposes of cultivation,

The snails are kept in a dark place in a wired cage with dry straw or dry wood.

Coppiced wine grape vines are often used for this purpose.

During the rainy period,

The snails come out of hibernation and release most of their mucus onto the dry wood or straw.

The snails are then prepared for cooking.

Their texture then cooked is slightly chewy and tender.

As well as being relished as gourmet food,

Several species of land snails provide an easily harvested source of protein to many people in poor communities around the world.

Many land snails are valuable because they can feed on a wide range of agricultural wastes,

Such as shed leaves and banana plantations.

In some countries,

Giant African land snails are produced commercially for food.

Land snails,

Freshwater snails,

And sea snails are all eaten in many countries.

In certain parts of the world,

Snails are fried.

For example,

In Indonesia,

They are fried as satay,

A dish known as satay kakul.

The eggs of certain snail species are eaten in a fashion similar to the way caviar is eaten.

In Bulgaria,

Snails are traditionally cooked in an oven with rice or fried in a pan with vegetable oil and red paprika powder.

Before they are used for those dishes,

However,

They are thoroughly boiled in hot water for up to 90 minutes and manually extracted from their shells.

The two species most commonly used for food in the country are Helix lucorum and Helix baumatia.

Snails and slug species that are not normally eaten in certain areas have occasionally been used as famine food in historical times.

A History of Scotland written in the 1800s recounts a description of various snails and their use as food items in times of plague.

Because of its slowness,

The snail has traditionally been seen as a symbol of laziness.

In Christian culture,

It has been used as a symbol of the deadly sin of sloth.

Psalms chapter 58 verse 8 uses snail slime as a metaphorical punishment.

In Mayan mythology,

The snail is associated with sexual desire,

Being personified by the god Uayyib.

Snails were widely noted and used in divination.

The Greek poet Hesiod wrote that snails signified the time to harvest by climbing the stalks,

While the Aztec moon god Texas Ticotle bore a snail shell on his back.

This symbolized rebirth.

The snail's penchant for appearing and disappearing was analogized with the moon.

Professor Ronald Chase of McGill University in Montreal has suggested the ancient myth of Cupid's arrow might be based on early observations of the love dart behavior of the land snail species Cornu aspersum.

In contemporary speech,

The expression a snail's pace is often used to describe a slow,

Inefficient process.

The phrase snail mail is used to mean regular postal service delivery of paper messages,

As opposed to the delivery of email,

Which can be virtually instantaneous.

In medieval and renaissance manuscripts,

Snails are depicted as a comic relief due to the similarity between the armor of knights and the shell of snails.

Keung emas,

Javanese and Indonesian for golden snail,

Is a popular Javanese folklore about a princess magically transformed and contained in a golden snail shell.

The folklore is a part of a popular Javanese Banji cycle,

Telling the stories about the princess Banji Asmoro Bangun and his consort Princess Dewi Sekartarji.

Certain varieties of snails,

Notably the family Moreside,

Produce a secretion that is a colorfast natural dye.

The ancient Tyrian purple was made in this way,

As were other purple and blue dyes.

The extreme expense of extracting this secretion in sufficient quantities limited its use to the very wealthy.

It is such dyes as these that led to certain shades of purple and blue being associated with royalty and wealth.

Throughout history,

Snails have been kept as pets,

There are many famous snails such as Lefty,

Born Jeremy,

And within fiction,

Gary and Brian the snail.

Tyrian purple,

Also known as royal purple,

Imperial purple,

Or imperial dye,

Is a reddish-purple natural dye.

The name Tyrian refers to Tyre,

Lebanon.

It is secreted by several species of predatory sea snails in the family Moreside,

Rock snails originally known by the name Murex.

In ancient times,

Extracting this dye involved tens of thousands of snails and substantial labor,

And as a result the dye was highly valued.

Biological pigments were often difficult to acquire,

And the details of their production were kept secret by the manufacturers.

Tyrian purple is a pigment made from the mucus of several species of Murex snail.

Production of Tyrian purple for use as a fabric dye began as early as 1200 B.

C.

By the Phoenicians and was continued by the Greeks and Romans until 1453 A.

D.

With the fall of Constantinople.

In the same way as the modern-day Latin alphabet of Phoenician origin,

Phoenician purple pigment was spread through the unique Phoenician trading empire.

The pigment was expensive and time-consuming to produce,

And items colored with it became associated with power and wealth.

This popular idea of purple being elite contributes to the modern-day widespread belief that purple is a royal color.

The color of textiles from this period provides insight into sociocultural relationships within ancient societies,

In addition to providing insights on technological achievements,

Fashion,

Social stratification,

Agriculture,

And trade connections.

Despite their value to archaeological research,

Textiles are quite rare in the archaeological record.

Like any perishable organic material,

They are usually subject to rapid decomposition and their preservation over millennia requires exacting conditions to prevent destruction by microorganisms.

Tyrian purple may first have been used by the ancient Phoenicians as early as 1570 B.

C.

It has been suggested that the name Phoenicia itself means land of purple.

The dye was greatly prized in antiquity because the color did not easily fade,

But instead became brighter with weathering and sunlight.

It came in various shades,

The most prized being that of black-tinted clotted blood.

Because it was extremely tedious to make,

Tyrian purple was expensive.

The 4th century B.

C.

Historian Theopompus reported,

Purple for dyes fetched its weight in silver at Colophon,

An Asia minor.

The expense meant that purple-dyed textiles became status symbols,

Whose use was restricted by sumptuary laws.

The most senior Roman magistrates wore a toga pretexta,

A white toga edged in Tyrian purple.

The even more sumptuous toga picta,

Solid Tyrian purple with gold-threaded edging,

Was worn by generals celebrating a Roman triumph.

By the 4th century A.

D.

,

Sumptuary laws in Rome had been tightened so much that only the Roman emperor was permitted to wear Tyrian purple.

As a result,

Purple is sometimes used as a metonym for the office,

E.

G.

The phrase Don the Purple means became emperor.

The production of Tyrian purple was tightly controlled in the succeeding Byzantine Empire and subsidized by the imperial court,

Which restricted its use for the coloring of imperial silks.

Later,

9th century,

A child born to a reigning emperor was said to be Porphyrogenitus,

Born in the purple.

Some speculate that the dye extracted from the Bolinos brandaris is known as argamon in Biblical Hebrew.

Another dye extracted from a related sea snail,

Hexaplex trunculus,

Produced a blue color after light exposure,

Which could be the one known as tekillet,

Used in garments worn for ritual purposes.

The dye substance is a mucus secretion from the hypobranchial gland of one of several species of medium-sized predatory sea snails that are found in the eastern Mediterranean Sea and off the Atlantic coast of Morocco.

These are the marine gastropods Bolinos brandaris,

The spiny dye Murex,

The branded dye Murex hexaplex trunculus,

The rock shell,

And less commonly a number of other species such as Bolinos cornutus.

The dye is an organic compound of bromine,

A class of compounds often found in algae and in some other sea life,

But much more rarely found in the biology of land animals.

This dye is in contrast to the cheaper imitation purple that was commonly produced,

Using cheaper materials than the dyes from the sea snail.

In nature,

The snails use the secretion as part of their predatory behavior to sedate prey and as an antimicrobial lining on egg masses.

The snail also secretes this substance when it is attacked by predators or physically antagonized by humans,

E.

G.

Poked.

Therefore,

The dye can be collected either by milking the snails,

Which is more labor-intensive but is a renewable resource,

Or by collecting and destructively crushing the snails.

David Jacobi remarks that 12,

000 snails of Murex brandaris yield no more than 1.

4 grams of pure dye,

Enough to color only the trim of a single garment.

Through the snail harvesting process,

Which includes the extraction of the hyprobrongiogland located into the mollusk's mantle,

The dye is collected,

Which required advanced knowledge of biology.

Murex-based dyeing must take place close to the site from which the snails originate,

Because the freshness of the material has a significant effect on the results.

The colors yielded based on the long process of biochemical,

Enzymatic,

And photochemical reactions,

And requires reduction and oxidation processes that probably took several days.

Many other species worldwide within the family Muricidae can also produce a similar substance,

Which churns into an enduring purple dye when exposed to sunlight,

And this ability has sometimes also been historically exploited by local inhabitants in the areas where these snails occur.

Some other predatory gastropods seem to also produce a similar substance,

Although this has not been studied or exploited commercially.

The dog whelk from the North Atlantic can also be used to produce red-purple and violet dyes.

The Phoenicians also made a deep blue colored dye,

Sometimes referred to as royal blue or hyacinth purple,

Which was made from a closely related species of marine snail.

The Phoenicians established an ancillary production facility on the Elis purpurarius at Mogador in Morocco.

The sea snail harvested at this western Moroccan dye production facility was Hexaplex trunculus,

Also known by the older name Murex trunculus.

The second species of dye,

Murex,

Is found today on the Mediterranean and Atlantic coasts of Europe and Africa,

Spain,

Portugal,

Morocco.

The colorfast non-fading dye was an item of luxury trade prized by Romans,

Who used it to color ceremonial robes.

Used as a dye,

The color shifts from blue to reddish purple.

It is believed that the intensity of the purple hue improved rather than faded as the dye cloth aged.

Vitruvius mentions a production of Tyrian purple from shellfish,

In his History of Animals.

Aristotle described the shellfish from which Tyrian purple was obtained and the process of extracting the tissue that produced the dye.

Pliny the Elder describes the production of Tyrian purple in his Natural History.

The most favorable season for taking these shellfish is after the rising of the dog star,

Or else before spring.

For when they have once discharged their waxy secretion,

Their juices have no consistency.

This,

However,

Is a fact unknown in the dyer's workshops,

Although it is a point of primary importance.

After it is taken,

The vein,

A hypobronchial gland,

Is extracted,

Which we have previously spoken of,

To which it is requisite to add salt,

A sextarius,

About twenty fluid ounces,

To every hundred pounds of juice.

It is sufficient to leave them to steep for a period of three days and no more,

For the fresher they are,

The greater virtue there is in the liquor.

It is then set to boil in vessels of tin or lead,

And every hundred amphorae ought to be boiled down to five hundred pounds of dye,

By the application of a moderate heat,

For which purpose the vessel is placed at the end of a long funnel,

Which communicates with the furnace,

While thus boiling the liquor is skimmed from time to time,

And with it the flesh,

Which necessarily adheres to the veins.

After the tenth day,

Generally,

The whole contents of the cauldron are in a liquefied state,

Upon which a fleece,

From which the grease has been cleansed,

Is plunged into it by way of making trial.

But until such time as the color is found to satisfy the wishes of those preparing it,

The liquor is still kept on the boil.

The tint that inclines to red is looked upon as inferior to that which is of a blackish hue.

The wool is left to lie and soak for five hours,

And then,

After carding it,

It is thrown in again,

Until it has fully imbibed the color.

Archaeological data from Tyre indicate that the snails were collected in large vats and left to decompose.

This produced a hideous stench that was actually mentioned by ancient authors.

Not much is known about the subsequent steps,

And the actual ancient method for mass-producing the two Morax dyes has not yet been successfully reconstructed.

This special blackish-clotted blood color,

Which was prized above all others,

Is believed to be achieved by double-dipping the cloth,

Once in the indigo dye of H.

Trunculus and once in the purple-red dye of B.

Brandaris.

The Roman mythographer Julius Pollux,

Writing in the second century A.

D.

,

Asserted that the purple dye was first discovered by the philosopher Heracles of Tyre,

Or rather by his dog,

Whose mouth was stained purple from chewing on snails along the coast of Tyre.

This story was depicted by Peter Paul Rubens in his painting,

Hercules' Dog Discovers Purple Dye.

According to John Malalas,

The incident happened during the reign of the legendary king Phoenix of Tyre,

The eponymous progenitor of the Phoenicians,

And therefore he was the first ruler to wear Tyrian purple and legislate on its use.

Recently,

The archaeological discovery of substantial numbers of Muric shells on Crete suggests that the Minoans may have pioneered the extraction of imperial purple centuries before the Tyrians.

Dating from co-located pottery suggests the dye may have been produced during the middle Minoan period in the 20th to 18th century B.

C.

Accumulations of crushed Muric shells from a hut at the site of Cappa Navigata in southern Italy may indicate production of purple dye there from at least the 18th century B.

C.

Additional archaeological evidence can be found from samples originating from excavations at the extensive Iron Age copper smelting sites of Slaves Hill,

Which is tightly dated by radiocarbon to the late 11th early 10th centuries B.

C.

Findings from this site include evidence of the use of purple dye found in stains used on pot shards.

Evidence of the use of dye in pottery are found in most cases on the upper part of ceramic basins on the inside surface.

The areas in which the reduced dye solution was exposed to air and underwent oxidation that turned it purple.

The production of Muric's purple for the Byzantine court came to an abrupt end with the sack of Constantinople in 1204,

The critical episode of the Fourth Crusade.

David Jacobi concludes that no Byzantine emperor nor any Latin ruler in former Byzantine territories could muster the financial resources required for the pursuit of Muric's purple production.

On the other hand,

Muric's fishing and dyeing with genuine purple are attested for Egypt in the 10th to 13th centuries.

By contrast,

Jacobi finds that there are no mentions of purple fishing or dyeing,

Nor trade in the colorant in any western source,

Even in the Frankish Levant.

The European West turned instead to vermilion provided by the insect Kermes vermilio,

Known as grana or crimson.

In 1909,

Harvard anthropologist Zelia Nuttall compiled an intensive comparative study on the historical production of the purple dye produced from the carnivorous Muric snail,

Source of the royal purple dye valued higher than gold in the ancient Near East and ancient Mexico.

Not only did the people of ancient Mexico use the same methods of production as the Phoenicians,

They also valued Muric's dyed cloth above all others,

As it appeared in codices as the attire of nobility.

Nuttall noted that the Mexican Muric's dyed cloth bore a disagreeable,

Strong,

Fishy smell,

Which appears to be as lasting as the color itself.

Likewise,

The ancient Egyptian papyrus of Anastasi laments,

The hands of the dyer reek like rotting fish.

So pervasive was this stench that the Talmud specifically granted women the right to divorce any husband who became a dyer after marriage.

In 2021,

Archaeologists found surviving wool fibers dyed with royal purple in the Timna Valley in Israel.

The find,

Which was dated to circa 1000 BC,

Constituted the first direct evidence of fabric dyed with the pigment from antiquity.

Muric's purple was a very important industry in many Phoenician territories,

And Carthage was no exception.

Traces of this once very lucrative industry are still visible in many Punic sites,

Such as Kerkouna,

Zouches,

Djerba,

And even in Carthage itself.

According to Pliny,

Mennings,

Today's Djerba,

Produced the best purple in Africa,

Which was also ranked second only after tires.

It was found also at Essaouira,

Morocco.

The royal purple,

Or imperial purple,

Was probably used until the time of Augustine of Hippo and before the demise of the Roman Empire.

Variations of colors of Tyrian purple from different snails are related to the presence of indigo dye,

Blue,

6-bromoindigo,

Purple,

And the red 6-6-dibromoindigo.

Additional changes in color can be induced by debromination from light exposure or by heating processing.

The final shade of purple is decided by chromatogram,

Which can be identified by HPLC analysis in a single measurement.

Indigotin,

Ind,

And indirubin,

Inr,

The two are found in plant sources such as woad and the indigo plant,

As well as in several species of shellfish.

In 1998,

By means of a lengthy trial and error process,

A process for dyeing with Tyrian purple was rediscovered.

This finding built on reports from the 15th century to the 18th century and explored the biotechnology process behind woad fermentation.

It is hypothesized that an alkaline fermenting vat was necessary.

An incomplete ancient recipe for Tyrian purple recorded by Pliny the Elder was also consulted.

By altering the percentage of sea salt in the dye vat and adding potash,

He was able to successfully dye wool a deep purple color.

Recent research in organic electronics has shown that Tyrian purple is an ambipolar organic semiconductor.

Transistors and circuits based on this material can be produced from sublimed thin films of the dye.

The good semiconducting properties of the dye originate from strong intermolecular hydrogen bonding that reinforces pi stacking necessary for transport.

True Tyrian purple,

Like most high chroma pigments,

Cannot be accurately rendered on a standard RGB computer monitor.

Ancient reports are also not entirely consistent.

The color named Tyrian plum is popularly given to a British postage stamp that was prepared but never released to the public shortly before the death of King Edward VII in 1910.

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