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One of the great mysteries of neurobiology is how memories are stored. We have a few tantalizing clues, but the precise biological mechanism for how memories are created and where they are stored in cells is still unknown. All of your lost loves and childhood dreams, your family’s birthdays and preferences, your own name and darkest secret…nobody knows where they are in your head. And, um, we still don’t know…however, thanks to research on sea snails, we have some new clues.
Scientists have long believed that memories are stored within the structure and connective patterns between the synapses which connect neurons. The new experiment suggests that this may prove to be a misconception.
Scientists trained a particular sort of sea snail (which have “small” brains with only 20,000 neurons) to respond in certain unusual ways to electrical shocks. Then the team removed ribonucleic acid (RNA), from nerve tissue of the trained snails and injected it into the circulatory system of untrained snails. Other “control” snails which were untampered with responded to electrical shocks naturally, however the snails which were treated with RNA from snails taught to curl their tails for prolonged periods immediately demonstrated this unusual behavior.
The findings suggest that our conjecture about where memories are stored may be quite wrong…or at least disturbingly incomplete. The snail research indicates that, at some fundamental level, memories are stored in the nuclei of neurons. Now scientists will try to replicate the results in other animals to test this hypothesis. Everything in this sort of research ends of being more complicated and interlinked than initially thought, so don’t forget about those synapses just yet. We are still at the beginning of this tantalizing scientific quest.
A Human Holding a Small Limpet
We live on the threshold of an era of stupendous nanomaterials! In the near future, molecules will be engineered to be harder than diamonds or stronger than steel…yet these miracle materials will also be workable and light.
Artist’s Conception of a Space Elevator–one of the miracles which should be possible through nanotechnology
Well, at least that’s what they keep telling us. In practice our best nano-materials do not seem capable of besting nature in the truly important categories—like hardness, tensile strength, or elasticity (or, if our synthetic materials are superior, they prove difficult to build into structures which fully exploit their strengths). A case in point comes from the lowly yet resilient limpet. Limpets are marine gastropods (snails) which have shells without visible coils. Actually, the name “limpet” is an informal common name—scientists have a very different way of characterizing these mollusks.
Common limpets (Patella vulgata) adhering to tidal zone rocks
Limpets cling tenaciously to rocks at the tidal line by means of a muscular foot designed to create suction. They also produce an adhesive mucus which helps the foot adhere to whatever surface the limpet wishes to cling to. They carefully scour their ocean rocks for nutritious algae with a radula—a tongue-like rasping organ covered with teeth. Limpets have been of note to humans principally as a metaphor for resilience…or as a nuisance. Yet scientists experimenting on a common limpet, Patella vulgata, found that the little snail’s teeth had greater tensile strength than spider silk. Indeed, limpet teeth are the strongest known material in the natural world and approach the tensile strength of our strongest carbon fibers. With these teeth the little snail can (and does!) chew through rocks.
A (horrifying) microscopic picture of limpet’s teeth
The secret to the limpet’s mighty teeth is a miracle of molecular design in its own right. The cutting portion of the teeth are composed of fibers of goethite (a sort of iron hydroxide named after the great German poet). These fibers are under 60 nanometers in diameter—a size which allows them to be tremendously strong. The teeth are technically a composite–since the tiny goethite fibers are held together by chitin, a natural polymer (which the exoskeletons of insects are made of).
This evil henchman was the best character.
Technically there are human-created carbon fibers stronger than the astonishing teeth of the limpet, but these fibers can only be utilized in certain configurations and fashions–so the limpets’ teeth are of very real practical interest to materials scientists. Engineers are already working on duplicating the little snail’s teeth for mining and cutting equipment…and for human dental uses. Perhaps we really could someday have some of the powers of Jaws, the lovable hulking henchman from seventies James Bond movies. With our synthetic chompers we could bite through rocks and steel cables. Uh, wouldn’t that be wonderful?
Snailovation (photo by @seaville)
Last September (2013) Sydney Australia was the location of “Snailovation” a massive public art project featuring 24 giant fluorescent snail sculptures made of recycled plastic. The event was meant to highlight the importance of ecological consciousness (and, of course, to raise awareness of gastropods—and mollusks in general). According to Weekendnotes.com “The gargantuan gastropods were created by international artistic collective Cracking Art Group whose members include William Sweetlove, Renzo Nucara, Marco Veronese, Kicco, Alex Angi and Carlo Rizetti.” I’m sorry I didn’t notice this story in time for you to get to Sydney and check out the huge plastic snails—which came down last October—but you can still enjoy the amazing photos!
Cracking Artgroup Facebook
Flowers on a Tree Trunk (Rachel Ruysch, ca. first half of 18th century)
Every once in a while, things go right for artists: Rachel Ruysch (1664-1750) lived a long prosperous life and found international success as a still life painter in an era when there were few women in the arts. Her father, Frederik Ruysch, was a famous professor of anatomy and botany who was renowned for his highly informative yet artistic anatomy displays (somewhat in the manner of famous contemporary body displays by the anatomist Gunther von Hagens). Professor Ruysch built strange and delicate landscapes out of preserved human organs and dissected bodies—particularly those of infants. He was renowned for his skill with various preservative regents and his secret liquor balsamicum was one of the wonders of the day—as were the novel human specimens he preserved within this embalming fluid. Rachel was expected to help by creating lace for the pieces and then arranging the bodies, limbs, appendages, and organs in an artistic fashion along with seashells and flowers (you’ll have to look that stuff up on your own, because it is the stuff of nightmares).
Because she worked closely with her father, interacted with famous artists of Holland’s golden age, and drew and organized the objects in her family’s famous curiosity cabinet, Rachel was well positioned to launch her own art career. She usually painted in the “dark background” still life style of de Heem and Willem Kalf, however many of her works demonstrated her background in the natural sciences. For example in “Flowers on a Tree Trunk” she boldly moves her composition from the parlor to the forest. A highly artificial flower bouquet of cabbage-roses, lilies, and irises dominates the composition—however, since this flower arrangement is located on the ground floor of a forest, the meaning is extremely different from more conventional vase paintings. Surrounded by wild creatures the bouquet invites the viewer to contrast the artificial beauty of flower arranging (or indeed of cultivated flowers themselves) with the chaotic beauty of a wild ecosystem of snakes, lizards, snails and butterflies.
Portrait of Rachel Ruysch (Godfried Schalcken, ca. 1706)
Japanese Bonnet Snail (Phalium/Semicassis bisulcata)
The helmet and bonnet snails (Cassidae) are slow moving hunters which live along sandy coasts in the tropics and subtropics. Depending on the species (of which tere are approximately 60), these sea snails live anywhere from the intertidal zone to a depth of 100 meters. During the day they bury themselves in the sand and at night they emerge to hunt their favorite prey—echinoderms (particularly sea urchins).
A Horned Helmet (Cassis cornuta) from the Hawaii coast
Most of the Cassidae are large snails with big mantles and heavy, muscular foot. They see by means of two eyes located at the base of a single pair of head tentacles and they use an extensible tube for smelling.
A helmet snail closes in on a sea urchin (image from wannadivekona.com)
When a helmet snail catches a tasty echinoderm, the snail immobilizes its prey by holding the smaller animal within its mighty foot and releasing a paralytic enzyme from its salivary gland (which prevents urchins from using their spikes in self-defense). The snail has a sharpened radula (an organ which consists of a chitinous tongue-like strip covered with razor sharp teeth) and two proboscis glands which produce a secretion rich in sulfuric acid. Using the combination of radula and acid, the helmet snail bores a hole in the echinoderm’s armored body and devours the creature from within!
Shells from the Cassidae family (from OuterBanksShells.com)
The shells of helmet snails are frequently large and beautiful. Shaped like a heavy helmet, these shells consist of dextral (right sided) coils which whorl outward from a tight spiral spire. The snails are divided into males and females (unlike many mollusks which are hermaphrodites or swap genders) and the females lay large masses of hundreds of eggs which can either hatch into planktonic free swimmers or into miniature crawling snails—depending on the species. Some Cassidae are prized by shell-hunters and artisans such as Cypraecassis rufa, a snail from the coast of Southeast Africa which is favored by cameo carvers.
Bullmouth Helmet Shell (Cypraecassis rufa) from the store “Evolution”
Colorful Land Snails (artist’s conception)
There are all sorts of snails in my Brooklyn garden which range in color from, well, from medium brown to dark brown. I guess the local mollusks don’t make for a very exciting rainbow–so today we move to the West Indies in search of the most vibrant land snails we can find. There are numerous lovely air-breathing snails throughout (and around) the Caribbean which can be found in a variety of eye-popping colors, but two particular species outshine the others in terms of brilliant red, yellow, black and orange swirls. These are the Cuban land snail (Polymita picta) and the Candy Stripe land Snail (Liguus virgineus) of Hispaniola.
Polymitas picta
Polymita picta lives throughout Cuba where it eats the algae, mold, and lichen from subtropical trees and shrubs. The single species of snails appear in a dazzling array of spiral color patterns.
Polymita picta color variation (Harvard Museum)
Liguus virgineus lives only on Hispaniola (the large island which includes Haiti & the Dominican Republic). Unlike the Cuban land snail, Liguus virgineus specimens are somewhat more homogenous in color and pattern. The Liguus genus however is broadly successful around the Caribbean and Gulf coast and the different species have different patterns (even though they are similar tree snails with similar habitats).
Liguus virginus
Map of Liguus Species
Sadly, both of these snails are at risk because of their brilliant color. The lovely bright colors have proven irresistibly attractive to the world’s most rapacious predator. Humans use the shells as jewelry or collectibles which has led to both species being over-harvested for collectors.
The Common Limpet (Patella vulgata)
Limpets are gastropods with simple cone-shaped shells. The majority of limpets are herbivores which live by grazing up films of algae by means of radula—an organ which is a tongue covered in rows of teeth. The most salient feature of limpets is their incredible tenacity. They cling to rocks and other haed surfaces with incredible tenacity—to such an extent that they have become synonymous with tenacity and obduracy. Brute force will not compel a limpet to stop clamping to a favored surface and the animal will allow itself to be destroyed before giving up its grip.
There are a number of limpet-like gastropods but the true limpets are named Patellogastropoda. The majority are tiny—less than 8 cm (3 inches) although a few larger species are known. Some limpets have a “home scar” on their favorite rock—a niche which fits them carefully and where they are perfectly camouflaged. Such limpets tend to be territorial and will fight for the grazing rights to algae near their scar.
Although limpets are most familiar to people at the tidal line (where rockbound limpets survive above the low tide line by adhering to rocks and tightly maintaining moisture) the creatures exist in numerous different marine ecosystems, including the depths of the sea, coral reefs, whale skeltons, seagrass forests, black smokers, and cold seeps. The deepwater limpets are probably detritivores. Limpets begin sexual life as males, but when they mature to a couple of years old they turn female. Young limpets undergo a brief larval stage before clamping down on a hard surface and stating to graze or forage.
A limpet shell pillbox
Ah Florida…sultry weather, orange groves, glistening beaches, pouting beauties, and palm trees…but also walking catfish, killer snakes, and now giant mollusks! The semi-tropical peninsula is prey to wave after wave of exotic animal invaders. The most-recent problem creatures are giant African snails, immense land snails that can grow up to 20 centimeters (8 inches) long. There are three extremely similar species of giant snails which come from West Africa: the giant African snail (Achatina fulica), the giant Ghana tiger snail (Achatina achatina), and the margies (Archachatina marginata). Each snail has a brown swirly shell and grows to be about the size of an adult’s fist.
Archachatina marginata
The giant snails eat over 500 varieties of plants—including the majority of agricultural and ornamental species. They also have a taste for stucco and siding so some Floridians now awaken to discover that huge mollusks are literally devouring their houses. The snails are hermaphrodites and can lay up to 12000 eggs per year. They can survive freezing temperatures.
Authorities continue to investigate how the snails got into the country but increasingly the evidence points to…voodoo.
In the Yoruba creation myth, the entire world was once water. The god Obatala possessed a magic snail shell which contained earth. Acting on instructions from the supreme divinity Olódùmarè, Obatala cast this land upon the oceans, thus creating the continents. Obatala then molded the land into men and beasts–but he possessed an artist’s temperament and thirst. As he crafted the Earth and its inhabitants he drank so much palm wine that his mental clarity became dulled and he made big parts of existence wrong. Eventually he passed out altogether and his brother Oduduwa was left to finish the work and patch up the errors as best as he could. Unfortunately big parts of humanity were assembled incorrectly and these flaws remain in evidence everywhere…
Obatala
Anyway a mainstay of Obatala worship is the sacrifice of snails (in memory of the primordial snail shell which contained the first earth). Apparently one of Obatala’s worshippers illegally brought some giant African snails into Florida for religious reasons and they escaped from him.
So, to recap, a smuggler who worships a drunken deity brought giant hermaphrodite snails in to Florida as a religious devotion to his addled god. Unfortunately the snails escaped and they are now eating people’s homes. Argh! What is wrong with us? I’m going to go drink some palm wine…
Next time please just light a votive candle!
Escargot
Heliciculture is the farming of snails for human consumption (and for snail mucous used in make-up and skin cream in the Latino community). Garbage middens from prehistoric settlements contain large numbers of cooked shells–so snails have been utilized as food for a long time. Sustained snail farming dates back at least to pre-Roman Phoenician colonies, however the ancient Romans took heliciculture and snail cooking to new levels. Romans gastronomes regarded snails as a particular delicacy and they introduced certain Mediterranean species to everywhere they conquered. When the empire fell apart Gaul continued the Roman tradition of enjoying escargot. Today the French alone consume 40,000 tons of snails per year. Serious agricultural effort is required to keep up with that sort of appetite.
Snails at market
Roman heliciculture apparently involved building little islands from which the snails could not escape. Today, however, snails are kept in carefully fenced garden plots. A small gauge metal wall which extends into the earth is necessary to keep snail predators out (particularly mice, shrews, raccoons, skunks, and toads) while a second interior wall made of specially constructed material keeps the snails in. A net can be added so that birds do not eat the tasty gastropods. Since pesticide and herbicide could injure the snails or the people eating them, organic greens are grown for the snails to consume. Apparently snails operate by Tron-style rules and do not like to cross another snail’s slime path—which means that only 20 snails can be kept per square meter. There are two principal species which are consumed as escargot. The smaller and more common Helix aspersa is also known as the “petit gris” or “escargot chagrine” whereas the larger, rarer Helix pomatia is called the “Roman snail,” “apple snail,” or “escargot de Bourgogne”. Both of these Mediterranean species have been widely introduced around the world for agricultural purposes. They are now endemic pests in Asia, Africa, Australia, New Zealand, North America and southern South America (and probably elsewhere). It’s funny to think that the snail eating your cabbages is the descendant of a snail which escaped from some long-dead hungry French chef. I can sort of imagine the scene as a black and white early Disney cartoon with giddy jazz playing in the background.
Snail Farming
Everybody and everything seems to enjoy eating snails including…other snails. A particular source of difficulty for snail farmers is cannibalism. Larger snails will eat eggs and hatchlings for the calcium. If not eaten by something, snails can live a long time. They hibernate in winter and Helix pomatia can live up to 35 years.
Helix pomatia
I had a post all planned for today but the difference between reality and fancy has forced me to scrap my original idea. First, and by way of overall explanation, allow me to apologize for not writing a post last Friday. I was attending a stamp convention in Baltimore over Labor Day weekend in order to fulfill a social obligation. The stamp convention is where my idea for today’s post came from and, of course it’s also where my idea went wrong.
I had initially (optimistically) planned on selecting a variety of stamps representing categories from my blog. What could be better than a bunch of tiny beautiful pictures of snakes, underworld gods, furry mammals, planetary probes, gothic cathedrals, and so forth? But, alas, my concept was flawed. The international postal industry is vast beyond the telling, and, undoubtedly, some nation on Earth has issued stamps featuring each of those subjects, however stamp collectors do not categorize their collections by subject. Instead they organize their precious stamps by pure obsession (usually but not always centered around a particular historical milieu). Apparently there are also subject stamp collectors out there…but real stamp collectors think of them the way that champion yachtsmen regard oafs on jet skis.
True philatelists are more interested in finding oddities which grow out of historical happenstance. Their great delights are the last stamps issued by an occupied country just before regime change, or the few stamps issued with the sultan’s head upside down, or a stamp canceled by a Turkmenistan post office which was destroyed a week after it was built. The nuances associated with such a subtle field quickly overwhelmed me. Additionally, I was unable to approach gray-haired gentlemen in waistcoats who were shivering in delight from looking at what appeared to be identical stamps with identical potentates and ask if there were any stamps with cuttlefish. It seemed blasphemous. I ended up leaving the stamp show without any stamps at all!
But don’t be afraid. There is an entity which is even more obsessive than the stamp dealers: the internet! To add to my previous post on catfish stamps here is a gallery of mollusk stamps which I found online. The beautiful swirls and dots and stripes of this handful of snails, octopuses, slugs, and bivalves should quickly convince you that even the world’s post offices have nothing on nature when it comes to turning out endless different designs.
ferrebeekeeper 