Abalone
Abalone (from Spanish Abulón) are medium-sized to very large edible sea snails, marine gastropod mollusks in the family Haliotidae and the genus Haliotis.

Common names for abalones also include ear-shells, sea-ears and Venus's-ears, as well as muttonfish or muttonshells in Australia, ormer in Jersey and Guernsey, perlemoen in South Africa and paua in New Zealand.

There is only the one genus in the family Haliotidae, and about four to seven subgenera. The number of species recognized worldwide ranges from about 100 to 130 (due to the occurrence of hybrids).

The shells of abalones have a low and open spiral structure, and are characterized by several respiratory holes in a row near the shell's outer edge. The thick inner layer of the shell is composed of nacre or mother-of-pearl, which in many species is highly iridescent, giving rise to a range of strong and changeable colors, which make the shells attractive to humans as decorative objects, and as a source of colorful mother-of-pearl.

The flesh (the adductor muscle) of abalones is widely considered to be a desirable food.

Description - The shell of abalones has a convex, rounded to oval shape, and the shell may be highly arched or very flattened. The shell is slightly spiral, with two to three whorls, the last one auriform such that the shell resembles an "ear", giving rise to the common name ‘ear-shell’. The body whorl has a series of holes—four to ten depending on the species—near the anterior margin, for the escape of water from the gills. There is no operculum.

The color of the shell is very variable from species to species. The iridescent nacre that lines the inside of the shell varies in color from silvery white, to pink, red and green-red, through to Haliotis iris, which shows predominantly deep blues, greens and purples.

These snails cling solidly with their broad muscular foot to rocky surfaces at sublittoral depths, although some species such as Haliotis cracherodii used to be common in the intertidal zone. Abalones reach maturity at a relatively small size. Their fecundity is high and increases with their size (from 10,000 to 11 million eggs at a time).

The larvae are lecithotrophic or feed off a yolk sac. The adults are herbivorous and feed with their rhipidoglossan radula on macroalgae, preferring red algae. Sizes vary from 20 mm (Haliotis pulcherrima) to 200 mm (or even more) (Haliotis rufescens).

Distribution - The haliotid family has a worldwide distribution, along the coastal waters of every continent, except the Atlantic coast of South America, the Caribbean, and the East Coast of the United States.

The majority of abalone species are found in cold waters, off the Southern Hemisphere coasts of New Zealand, South Africa and Australia, and Western North America and Japan in the Northern Hemisphere.

The species of sea snail which is known in the sea food trade as the "Chilean abalone", Concholepas concholepas, is from another family altogether. It is not a true abalone at all, but a muricid, or rock snail.

Human Use - Abalone has long been a valuable food source for humans in every area of the world where a species is, or used to be, abundant. The various larger species of abalones have been exploited commercially for food to the extent that many populations are now severely threatened.

The highly iridescent inner nacre layer of the shell of abalone has traditionally been used as a decorative item in jewelry, buttons, and as inlay in furniture and in musical instruments such as guitars, etc.

Structure and properties of abalone shell - The shell of the abalone is exceptionally strong. It is made of microscopic calcium carbonate tiles stacked like bricks. Between the layers of shells is a clingy protein substance. When the abalone shell is struck, the tiles slide instead of shattering and the protein stretches to absorb the energy of the blow. Material scientists around the world are studying the tiled structure for insight into stronger ceramic products such as body armor.

The dust created through the grinding and cutting of abalone shell is dangerous; appropriate safeguards should be taken to protect a person from inhaling these particles. An N95-rated dust respirator, a ventilation system, and wet grinding are requirements to working the shell safely. The calcium carbonate is a respiratory irritant and the particles can penetrate into the lower respiratory tree and cause irritant bronchitis and other respiratory irritation responses. The usual symptoms are cough and sputum production, and secondary infections can occur. If there are proteins left in the shell matrix, it is also possible that they can trigger an allergic (asthmatic) attack. In general, the more someone is exposed to something that triggers their asthma reaction, the larger the reaction. Allergic skin reactions can also occur.

Diseases - Abalones are subject to various diseases. The NSW Department of Primary Industry said in 2007 that abalone viral ganglioneuritis, or AVG, killed up to 90% of stock in affected regions. Using abalone as bait or burley is thus illegal in NSW.

South Africa - The largest abalone in South Africa, the Perlemoen, Haliotis midae, occurs along approximately two-thirds of the country’s coastline. Perlemoen-diving has been a recreational activity for many years, but stocks are currently being threatened by illegal commercial harvesting. In South Africa all persons harvesting this animal need permits that are issued on a yearly basis, and no abalone may be harvested using scuba gear.

For the last few years, however, no permits have been issued for collecting Abalone (Perlemoen), but commercial harvesting still continues as does illegal collection by syndicates. In 2007, because of widespread poaching of abalone, the South African government listed perlemoen as an endangered species according to the CITES section III appendix, which requests member governments to monitor the trade in this species. The abalone meat from South Africa is prohibited for sale in the country to help reduce poaching -- however, much of the illegally harvested meat is sold in Asian countries. As of early 2008, the wholesale price for abalone meat was approximately US$40.00 per kilogram. There is an active trade in the shells which sell for more than US$1,400 per metric ton. There is, however, speculation that local criminal gangs barter Abalone illegally with Chinese nationals in exchange for chemicals used in the production of drugs, reducing the need for the use of money and hence avoiding money laundering issues.

Farming - Farming of abalone began in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, there have been many increasingly successful endeavors to commercially farm abalone for the purpose of consumption. Over-fishing and poaching have reduced wild populations to such an extent that farmed abalone now supplies most of the abalone meat consumed. The principal abalone farming regions are China's mainland, Taiwan, Japan and Korea. Abalone is also farmed in Australia, Canada, Chile, Iceland, Ireland, Mexico, Namibia, New Zealand, South Africa, Thailand, and the United States.

Consumption - The meat of this mollusk is considered a delicacy in certain parts of Latin America (especially Chile), New Zealand, South East Asia, and East Asia (especially in China, Japan, and Korea). In Chinese speaking regions, abalone are commonly known as bao yu, and sometimes forms part of a Chinese banquet. Similar to shark fin soup, it is considered a symbol of wealth and prestige, and is traditionally reserved for special occasions such as weddings and other celebrations. However, the availability of commercially farmed abalone has allowed more common consumption of this once rare delicacy.

Source: Wikipedia, the free encyclopedia