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| Dorsal (left) and ventral (right) views of the blacklip abalone |
Abalone (æbəloʊniː/ or /ˌæbəˈloʊniː/; via Spanish abulón, from the (Rumsen language) aulón), is a common name for any of a group of small to very large edible sea snails, marine gastropod molluscs in the family Haliotidae. Other common names are ear shells, sea ears, and muttonfish or muttonshells in Australia, ormer in Great Britain, Abalone and venus's-ears in South Africa, and pāua in New Zealand.
The family Haliotidae contains only one genus, Haliotis, which contains about 4 to 7 subgenera. The number of species recognized worldwide ranges between 30 and 130 with over 230 species-level taxa described. The most comprehensive treatment of the family considers 56 species valid, with 18 additional subspecies.
The shells of abalones have a low open spiral structure, and are characterized by several open respiratory pores in a row near the shell's outer edge. The thick inner layer of the shell is composed of nacre (mother-of-pearl), which in many species is highly iridescent, giving rise to a range of strong changeable colors, which make the shells attractive to humans as decorative objects, jewelry, and as a source of colorful mother-of-pearl.
The flesh of abalones is widely considered to be a desirable food, and is consumed raw or cooked in a variety of dishes.
The shell of abalones is convex, rounded to oval shape, and may be highly arched or very flattened. The shell
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| Abalone with a live sponge in its shell |
is generally ear-shaped, presenting a small flat spire and two to three whorls. The last whorl (known as the body whorl) is auriform, meaning that the shell resembles an ear, giving rise to the common name "ear shell". The "ass’s ear" abalone has a somewhat different shape, as it is more elongated and distended. The shell of Haliotis cracherodii cracherodii Leach, 1814 is also unusual: it has an ovate form, it is imperforate, shows an exserted spire, and has prickly ribs.
A mantle cleft in the shell impresses a groove in the shell, in which are the row of holes characteristic of the genus. They are respiratory apertures for venting water from the gills and for releasing sperm and eggs into the water column. These holes make up what is known as the selenizone which form as the shell grows. This series of 8 to 38 holes is near the anterior margin. Only a small number are generally open. The older holes are gradually sealed up as the shell grows and new holes form. Each abalone species has a typical number of open holes in the selenizone. There are four to ten of these holes, depending on the species. Abalone have no operculum. The aperture of the shell is very wide and nacreous.
The exterior of the shell is striated and dull. The color of the shell is very variable from species to species, and may reflect the animal's diet. 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.
The animal shows fimbriated[disambiguation needed] head-lobes. The side-lobes are fimbriated and cirrated. The rounded foot is very large. The radula has small median teeth, and the lateral teeth are single and beam-like. There are about 70 uncini, with denticulated hooks, the first four very large. The soft body is coiled around the columellar muscle, and its insertion, instead of being on the columella, is on the middle of the inner wall of the shell. The gills are symmetrical and both well developed.
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 spermatozoa are filiform and pointed at one end, and the anterior end is a rounded head.
The larvae are lecithotrophic (i.e. feed off a yolk sac). The adults are herbivorous and feed with their rhipidoglossan radula on macroalgae, preferring red or brown algae. Sizes vary from 20 mm (Haliotis pulcherrima) to 200 mm (or even more) (Haliotis rufescens).
Abalones are herbivorous on hard substrata.
By weight, approximately 1/3 of the animal is edible meat, 1/3 is offal, and 1/3 is shell.
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.
However, the species of sea snail which is known in the seafood trade as the "Chilean abalone", Concholepas concholepas, is from another family altogether. It is not a true abalone, but a carnivorous muricid, or rock snail. It lives in rocky areas.
The meat (foot muscle) of abalone is used for food, and the shells of abalone are used as decorative items and as a source of mother of pearl for jewelry, buttons, buckles, and inlay. Abalone shells have been found in archaeological sites around the world, ranging from 75,000 year old deposits at Blombos Cave in South Africa to historic Chinese abalone middens on California's Northern Channel Islands. On the Channel Islands, where abalones were harvested by Native Americans for at least 12,000 years, the size of red abalone shells found in middens declines significantly after about 4000 years ago, probably due to human predation. Worldwide, abalone pearls have also been collected for centuries.
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| An abalone farm |
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, Taiwan, Japan, and Korea. Abalone is also farmed in Australia, Hawaii, Canada, Chile, France, Iceland, Ireland, Mexico, Namibia, New Zealand, South Africa, Thailand, and the United States.
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| Braised abalones |
Abalone have long been a valuable food source for humans in every area of the world where a species is abundant.
The meat of this mollusk is considered a delicacy in certain parts of Latin America (especially Chile), France, New Zealand, Southeast 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 or bird's nest soup, it is considered a luxury item, 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.
In Japan, live and raw abalone are used in awabi sushi, or served steamed, salted, boiled, chopped, or simmered in soy sauce. Salted, fermented abalone entrails are the main component of tottsuru, a local dish from Honshū. Tottsuru is mainly enjoyed with sake.
In California, abalone meat can be found on pizza, sautéed with caramelized mango or in steak form dusted with cracker meal and flour.
Sport harvesting of red abalone is permitted with a California fishing license and an abalone stamp card. New in 2008, the abalone card also comes with a set of 24 tags. Legal-size abalone must be tagged immediately. Abalone may only be taken using breath-hold techniques or shorepicking; scuba diving for abalone is strictly prohibited. Taking of abalone is not permitted south of the mouth of the San Francisco Bay. There is a size minimum of seven inches (178 mm) measured across the shell and a quantity limit of three per day and 24 per year. A person may be in possession of only three abalone at any given time.
Abalone may only be taken from April to November, not including July. Transportation of abalone may only legally occur while the abalone is still attached in the shell. Sale of sport-obtained abalone is illegal, including the shell. Only red abalone may be taken; black, white, pink, and flat abalone are protected by law.
An abalone diver is normally equipped with a thick wetsuit, including a hood, bootees, and gloves, and usually also a mask, snorkel, weight belt, abalone iron, and abalone gauge. Alternatively, the rock picker can feel underneath rocks at low tides for abalone. Abalone are mostly taken in depths from a few inches up to 10 m (33 ft); less common are freedivers who can work deeper than 10 m (33 ft). Abalone are normally found on rocks near food sources (kelp). An abalone iron is used to pry the abalone from the rock before it can fully clamp down. Divers dive out of boats, kayaks, tube floats or directly off the shore.
The largest abalone recorded in California is 12.34 inches, caught by John Pepper somewhere off the coast of San Mateo county in September 1993.
The mollusc Concholepas concholepas is often sold in the United States under the name "Chilean abalone", though it is not an abalone, but a muricid.
Abalones have been identified as one of the many classes of organism threatened with extinction due to overfishing, acidification of oceans from anthropogenic carbon dioxide, as reduced pH erodes their shells. It is predicted that abalones will become extinct in the wild within 200 years at current rates of carbon dioxide production.
