The skin of a shark was once used commercially as sandpaper. True or false?
"The danger he saw was that ""through this false self, the infant builds up a false set of relationships, and by means of introjections even attains a show of being real"", while, in fact, merely concealing a barren emptiness behind an independent-seeming façade. The danger was particularly acute where the baby had to provide attunement for the mother/parents, rather than vice versa, building up a sort of dissociated recognition of the object on an impersonal, not personal and spontaneous basis. But while such a pathological false self stifled the spontaneous gestures of the true self in favour of a lifeless"
"natural gum. Shark skin (placoid scales) has also been used as an abrasive and the rough scales of the living fossil, Coelacanth are used for the same purpose by the natives of Comoros. Boiled and dried, the rough horsetail plant is used in Japan as a traditional polishing material, finer than sandpaper. Glass paper was manufactured in London in 1833 by John Oakey, whose company had developed new adhesive techniques and processes, enabling mass production. Glass frit has sharp-edged particles and cuts well whereas sand grains are smoothed down and do not work well as an abrasive. Cheap sandpaper was"
"half of the shark has a gray color with scattered white spots while the bottom half has a white/light gray color. The scales of the dogfish is composed of the same material of shark teeth called dermal denticles, making the skin very hard and durable. The skin of the sharks used to be used as sandpaper once dried to do woodwork or even be used as leather, once the denticles are removed. Lastly, the Pacific spiny dogfish has a set of teeth specialized for grinding instead of tearing by the teeth being flat with sharp edges. If any of the"
"of its body grates over the surface of its enemy with the rugged spines of its skin, like a rasp. There are few animals that can bear so severe an infliction, by which their surface is torn with lacerated wounds."" This shark is displayed by many public aquariums and has been bred in captivity. The rough skin (called ""rubskin"") of the nursehound was once used to polish wood and alabaster, to smooth arrows and barrels, and to raise the hairs of beaver hats as a replacement for pumice. Rubskin was so valued that a pound of it was worth a"
"angelshark for thousands of years. Ancient Greek authors, such as Diphilus and Mnesitheus, described its meat as ""light"" and ""easily digestible"", and Pliny the Elder noted in his ""Naturalis Historia"" (77–79 AD) that its rough skin was valued by craftsmen for polishing wood and ivory. Aristotle recorded elements of its natural history, including that it bore live young, and correctly recognized that it was a shark despite its resemblance to rays and skates. The use of this species for food has continued into modern times; it is sold fresh or dried and salted, often under the name ""monkfish"" (which also"
"the surface, interacting only with the riblet tips, not causing any high-veloctiy flow in the valleys. Since this high velocity flow now only interacts with the riblet-tip, which is a very small surface area, the momentum transfer which causes drag is now much lower than before, thereby effectively reducing drag. Also, this reduces the cross-stream velocity fluctuations, which aids in momentum transfer too. The rough, sandpaper-like texture of shark and ray skin, coupled with its toughness, has led it to be valued as a source of rawhide leather, called shagreen. One of the many historical applications of shark shagreen was"
"amyotrophic lateral sclerosis. However, shark cartilage supplements are still marketed using the misconception that sharks do not get cancer, a myth that was as popularized by the 1992 book ""Sharks Don't Get Cancer"". In the United States, the Federal Trade Commission has taken legal action against such fraudulent promoters. Tumors of many kinds, some metastatic, have been found in numerous species of sharks. The first shark tumor was recorded in 1908. Scientists have since discovered 40 benign and cancerous tumors in 18 of the 1,168 species of sharks. Scarcity of studies on shark physiology has perhaps allowed the myth to"
"skin is made into leather products. Spinner sharks are an important catch of the US commercial shark fisheries operating in the northwestern Atlantic and the Gulf of Mexico. The meat is marketed under the name ""blacktip shark"" in the United States, due to that species being considered superior in quality by consumers. It is likely also caught by other fisheries across its range, going unreported owing to confusion with the blacktip shark. The spinner shark is also highly regarded by recreational fishers, being described as a ""spectacular fighter"" that often leaps out of the water. The IUCN has assessed the"
"in making hand-grips for swords. The rough texture of the skin is also used in Japanese cuisine to make graters called ""oroshiki"", by attaching pieces of shark skin to wooden boards. The small size of the scales grates the food very finely. There are many examples of biomimetic materials and surfaces based on the structure of aquatic organisms, including sharks. Such applications intend to enable more efficient movement through fluid mediums such as air, water and oil. Surfaces that mimic the skin of sharks have also been used in order to keep microorganisms and algae from coating the hulls of"
"patients receiving shark cartilage and those taking a placebo. Scientific evidence does not support the efficacy of shark cartilage nor the ability of effective components to remove cancer cells. The fact that people believe eating shark cartilage can cure cancer shows the serious potential impacts of pseudoscience. Detractors also purport that previous beliefs in regards to sharks and cancer have been overturned, as forty-two varieties of cancer have now been discovered in sharks and related species. Also, many opponents feel that non-existent (or even limited) results do not justify the rampant over-fishing of many endangered species of sharks, further threatening"
"and the shark cartilage powder is still widely marketed as a cancer cure, stated to be selling at US$145 per gram. It is also stated that in Costa Rica, one single firm alone processed 235,000 sharks every month to manufacture cartilage pills. Since the late 1980s populations of northwest Atlantic coastal and oceanic shark have dropped by an average of 70%, and in 2003 the World Conservation Union (IUCN) estimated that tens of millions of sharks are finned and discarded at sea every year. However, estimates are muddy given the fact that the sharks and their fins cross-cut different fishing"
"half the global trade. The meat (sold fresh or dried and salted), skin, and liver oil may also be used, as well as the jaws: this species is the predominant source of dried shark jaw curios sold to tourists in the tropics. Some sport fishers catch silky sharks. As one of the most abundant and widely distributed sharks on Earth, the silky shark was once thought to be mostly immune to depletion despite heavy fishing mortality. In 1989 alone, some 900,000 individuals were taken as bycatch in the southern and central Pacific tuna longline fishery, seemingly without effect on the"
"The endangered aspect of this shark was publicised in 2005 with a postage stamp issued by Guernsey Post. Historically, the basking shark has been a staple of fisheries because of its slow swimming speed, placid nature, and previously abundant numbers. Commercially, it was put to many uses: the flesh for food and fishmeal, the hide for leather, and its large liver (which has a high squalene content) for oil. It is currently fished mainly for its fins (for shark fin soup). Parts (such as cartilage) are also used in traditional Chinese medicine and as an aphrodisiac in Japan, further adding"
"eating shark. For details see mercury in fish. In the South Asian region, use of shark cartilage in preparing soups is considered a health tonic. Hong Kong imports it from North and South American countries, particularly for use in either a cooked format or to prepare boiled soup, as a health fad, by mixing it with herbals supplements. Another large demand for shark cartilage is for manufacture of ""Shark Cartilage Powder"" or pills as a cure for cancer. The anti cancer claims of such powders marketed in many parts of the world has been discounted by the US Food and"
"cake form using a water-soluble wax binder and rigged to life vests. The Navy employed Shark Chaser extensively between 1943 and 1973. It is believed that the composition does repel sharks in some situations, but not in all, with about a 70% effectiveness rating. On the other hand, Albert Tester questioned the idea that dead shark bodies or chemicals based on them could work as shark repellent. In 1959, he prepared and tested extracts of decaying shark flesh on tiger sharks in Hawaii and blacktip sharks at Enewetak Atoll. Tester found that not only did the dead shark extracts fail"
"guanaco or alpaca in such blends: inclusion of silk (then a very costly fiber) was even more common among the ""natural sharkskins"". Whereas, ""artificial sharkskin"", a much less costly substitute, is a fabric variant that is more often found from that period and can contain synthesized or synthetic fibers that were developed contemporary to those eras. Artificial sharkskin variants used for suiting first appeared in the 1950s and rapidly garnered worldwide appeal in artificial sharkskin (costing much less than its ""natural"" counterpart: which most consumers were not aware existed, so far out of their price range it remained), attaining broad"
"all paleontologists agree that these are from true sharks, suspecting that these scales are actually those of thelodont agnathans. The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period. The first sharks looked very different from modern sharks. At this time the most common shark tooth is the cladodont, a style of thin tooth with three tines like a trident, apparently to help catch fish. The majority of modern sharks can be traced back to around 100 million years ago. Most fossils are of teeth, often in large numbers. Partial skeletons and even"
"often passed off as glass paper; Stalker and Parker cautioned against it in ""A Treatise of Japaning and Varnishing"" published in 1688. In 1921, 3M invented a sandpaper with silicon carbide grit and a waterproof adhesive and backing, known as ""Wet and dry"". This allowed use with water, which would serve as a lubricant to carry away particles that would otherwise clog the grit. Its first application was in automotive paint refinishing. There are many varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond. In addition to paper,"
"material was developed by Dr. Tony Brennan, material science and engineering professor at University of Florida while trying to improve antifouling technology for ships and submarines at Pearl Harbor. Brennan realized that sharks do not experience fouling. He observed that shark skin denticles are arranged in a distinct diamond pattern with millions of tiny ribs. The width-to-height ratio of shark denticle riblets corresponded to his mathematical model for the texture of a material that would discourage microorganisms from settling. The first test performed showed an 85% reduction in green algae settlement compared to smooth surfaces. Sharklet's texture is a combination"
"or if the technique was developed separately. In the 17th and early 18th centuries, the term ""shagreen"" began to be applied to leather made from sharkskin or the skin of a rayfish (probably the pearled ray, ""Hypolophus sephen""). This form is also termed sharkskin or galuchat. Such skins are naturally covered with round, closely set, calcified papillae called placoid scales, whose size is chiefly dependent on the age and size of the animal. These scales are ground down to give a roughened surface of rounded pale protrusions, between which the dye (again, typically green vegetable dye) shows when the material"
"Shark cartilage Shark cartilage is a dietary supplement made from the dried and powdered cartilage of a shark; that is, from the tough material that composes a shark's skeleton. Shark cartilage is marketed under a variety of brand names, including Carticin, Cartilade, or BeneFin, and is marketed explicitly or implicitly as a treatment or preventive for various illnesses, including cancer. There is no scientific evidence that shark cartilage is useful in treating or preventing cancer or other diseases. Controlled trials have shown no benefit to shark cartilage supplements, and shark cartilage contains potentially toxic compounds linked to Alzheimer's disease and"
"earliest authenticated pictorial piece of sperm whale scrimshaw (1817). The tooth was inscribed: ""This is the tooth of a sperm whale that was caught near the Galapagos islands by the crew of the ship Adam [of London], and made 100 barrels of oil in the year 1817."" Other sea animal ivories were also used as alternatives for rarer whale teeth. Walrus tusks, for example, may have been acquired in trade from indigenous walrus hunters. Scrimshaw essentially was a leisure activity for whalers. Because the work of whaling was very dangerous at the best of times, whalers were unable to work"
"hundredweight of sandpaper. The liver was also used as a source of oil, and the carcasses cut up and used to bait crab traps. The meat of this species is marketed fresh or dried and salted, though it is considered ""coarse"" in some quarters. In the United Kingdom, it is one of the species sold under the names ""flake"", ""catfish"", ""huss"" ""rock eel"", or ""rock salmon"". In France, it is sold as ""grande roussette"" or ""saumonette"", as after being skinned and beheaded it resembles salmon. This species is also sometimes processed into fishmeal, or its fins dried and exported to"
"be accepted as fact for so many years. Numerous cancers in sharks, including tumors in shark cartilage, were documented by Gary Ostrander and his colleagues from the University of Hawaii in research published in 2004. The ongoing consumption of shark cartilage supplements has been linked to a significant decline in shark populations and the popularity of these supplements has been described as a triumph of pseudoscience and marketing over scientific evaluation. Manufacturers of shark cartilage supplements provide anecdotal testimonials from those who claim to have experienced relief from arthritis symptoms and pain, as a result of taking shark cartilage supplements."
"their extinction. In the summer of 2004, Lane Labs, the manufacturers of BeneFin, was ordered to cease the promotion of BeneFin as a treatment or cure for cancer, as they had not conducted any research as to their claims for the product, much less reported any potential side effects. Thus, the FDA ordered Lane Labs to ""pay restitution to all of its customers from September of 1999 to the present."" Shark cartilage Shark cartilage is a dietary supplement made from the dried and powdered cartilage of a shark; that is, from the tough material that composes a shark's skeleton. Shark"
"In many parts of the world, including the US, hagfish skin is used for clothing, belts, or other accessories. In the United States, the black hagfish has been trapped for commercial purposes. Trapping in Oregon began in October, 1988 in Newport. The hagfish are frozen whole, at sea, and then shipped to South Korea. Recent studies have shown that hagfish slime has similar properties of spider silk, strong and light. If hagfish slime could be replicated in laboratories it could replace artificial materials, like nylon, in women's stockings and workout pants. This would ultimately be better for the environment since"
"countries and while some prescription medicines are available with this effect, unauthorized sales are illegal. Some prosecutions have been pursued over unlicensed sales of escharotic products such as Cansema. Eschar An eschar (; Greek: ""eschara"") is a slough or piece of dead tissue that is cast off from the surface of the skin, particularly after a burn injury, but also seen in gangrene, ulcer, fungal infections, necrotizing spider bite wounds, spotted fevers and exposure to cutaneous anthrax. The term ""eschar"" is not interchangeable with ""scab"". An eschar contains necrotic tissue, whereas a scab is composed of dried blood and exudate."
"Silky shark The silky shark (""Carcharhinus falciformis""), also known by numerous names such as blackspot shark, grey whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. Highly mobile and migratory, this shark is most often found over the edge of the continental shelf down to . The silky shark has a slender, streamlined body and"
"submarines and ships. One variety is traded as ""Sharklet"". A lot of the new methods for replicating sark skin involve the use of polydimethylsiloxane (PDMS) for creating a mold. Usually the process involves taking a flat piece of shark skin, covering it with the PDMS to form a mold and pouring pdms into that mold again to get a shark skin replica. This method has been used to create a biomimetic surface which has superhydrophobic properties, exhibitng the Lotus effect. One study found that these biomimetic surface reduced drag by up to 9%, while with flapping motion drag reduction reached"
"Drug Administration, Federal Trade Commissions and medical studies. In spite of such injunctions, the trade in this powder continues and the shark cartilage powder is still widely marketed as a cancer cure, stated to be selling at US$145 per gram. It is also stated that in Costa Rica, one single firm alone processed 235,000 sharks every month to manufacture cartilage pills. Seafood Watch recommends that everyone avoid eating shark. The majority of shark fisheries around the globe have little monitoring or management. With the rise in demand for shark products there is a greater pressure on fisheries. Sharks experience a"
"the effectiveness of semiochemicals as a shark repellent was conducted by scientists from SharkDefense Technologies and Seton Hall University. The study's results were published in the scientific journal ""Ocean & Coastal Management"" in 2013. The study concluded that the existence of a putative chemical shark repellent has been confirmed. As of 2014, SharkDefense partnered with SharkTec LLC to manufacture the semiochemical in a canister as a shark repellent for consumers called Anti-Shark 100. Recently, SharkDefense used the same semiochemicals found in SharkTec's product to reduce shark by-catch by 71% in a government grant initiative. The government agency NOAA released these"
"fins for use in shark fin soup, on level with tiger, mako, blue, porbeagle, thresher, hammerhead, blacktip, sandbar and bull shark. As traditional medicine (especially Chinese medicine, but also known from Mexico, Brazil, Kenya, Eritrea, Yemen, Iran, India and Bangladesh) sawfish parts, oil or powder have been claimed to work against respiratory ailments, eye problems, rheumatism, pain, inflammation, scabies, skin ulcers, diarrhea and stomach problems, but there is no evidence supporting any of these uses. The saws are used in ceremonies and as curiosities. Until relatively recently many saws were sold to visiting tourists, or through antique stores or shell"
"at around long respectively; the fact that females mature at a smaller size than males is unusual among sharks. Though not normally aggressive towards humans, the sand devil can inflict serious wounds if provoked. Its common name refers to its habit of snapping vigorously at fishery workers when caught, and even out of the water it is capable of lunging upwards to bite. This shark is caught incidentally in bottom trawls operated by commercial fisheries targeting other species. It is edible but seldom brought to market. The International Union for Conservation of Nature (IUCN) presently lacks the data to list"