''Bullacta exarata'',

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

the Korean mud snail, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of a

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

or bubble snail, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Haminoeidae Haminoeidae, commonly known as the haminoeid bubble snail family, is a taxonomic family of sea snails, marine opisthobranch gastropod mollusks in the superfamily Haminoeoidea. The name of this family has long been controversial, and used to be ...

, the bubble snails. ''Bullacta exarata'' is a commercially important mollusc which is used as a food item in eastern China.

Taxonomy

''Bullacta exarata'' is the only species in the genus ''Bullacta''. cf. ''Bullacta'' is the type genus of the family Bullactidae Thiele, 1926, as shown in the taxonomy of the Gastropoda by Bouchet & Rocroi (2005). Based on phylogenetic genetic analysis by Malaquias (2010), ''Bullacta exarata'' should be placed in the family

Distribution

''Bullacta exarata'' is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to coastlines of the

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

and

East China Sea The East China Sea is a marginal sea of the Western Pacific Ocean, located directly offshore from East China. China names the body of water along its eastern coast as "East Sea" (, ) due to direction, the name of "East China Sea" is otherwise ...

s from

Hainan Hainan is an island provinces of China, province and the southernmost province of China. It consists of the eponymous Hainan Island and various smaller islands in the South China Sea under the province's administration. The name literally mean ...

to the

Bohai Sea The Bohai Sea ( zh, c=渤海, p=Bó Hǎi, l=Bo Sea) is a gulf/inland sea approximately in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects via the Bohai Strait. It ...

in north-eastern China, the western coast and south coast of Korea and Japan.Ye S.-F. & Lu J.-J. (2001) "Analysis on the spatial distribution of ''Bullacta exarata'' (Mollusca: Gastropoda: Atyidae) population in Yangtze River Estuary, China". '' Zool Res'' 22: 131-136.
abstract
An

ecotype Ecotypes are organisms which belong to the same species but possess different phenotypical features as a result of environmental factors such as elevation, climate and predation. Ecotypes can be seen in wide geographical distributions and may event ...

of this snail introduced from further south has become invasive in

Laizhou Bay Laizhou Bay () is a bay on the southern shore of the Bohai Sea (also known as the ''Bohai Gulf'', or just ''Bo Hai'', which is a large and relatively shallow westward extension of the northern Yellow Sea), bounded by the northwestern coastline o ...

, with population densities of over 160 snails per square meter.

Description

The

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

is bullate, fairly thick, white, spirally striate, with a well-developed

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods an ...

. There is no

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spire ...

and no umbilicus. The

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

is smooth and simple. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

extends for the whole length of the shell, and is narrower above than below. The apertural lip extends upwards beyond the

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

of the shell. The height of the shell is 8 mm and the width of the shell is 6 mm. The animal cannot withdraw itself into the shell, which contains the visceral hump only. The cephalic disc is large and slipper-shaped, feebly emarginate on the dorsal surface behind and with a narrow free margin. The cephalic disc, which is rounded in front, occupies about half of the whole bulk in a contracted state. The edge of the mantle is smooth, without processes of any kind. It, the edge of the mantle (which is slightly retroverted over that of the shell), the foot and the epipodia are (in alcohol) of a pale green colour. The greater part of the mantle, however, under the shell is colourless and transparent. The foot is short, truncate before and behind, and with the epipodia (in much contracted specimens) apparently not well developed. The eyes are minute and quite invisible on the surface. The eyespots are deeply sunk in the tissues. The gill, which is situated far back on the right side, is large and consists of a considerable number of fleshly lobes. Bullacta exarata radula

Digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

: The mouth is a minute transverse slit in the front of the cephalic disc. The jaws are large, but imperfectly cornified. The jaws are angular and minutely, irregularly serrate. They are composed of numerous minute prismatic rods. On the margin many of these rods are transverse and project slightly, forming a minute serration. The radular sack is small. The

radula The radula (; : radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters ...

has the formula 12.1.1.1.12. The central tooth is a simple flat triangular plate. The single lateral tooth is well differentiated from the marginal teeth, from which it is separated by a considerable space, and points in the opposite direction. The marginal teeth are slender, elongate, curved rod-like bodies somewhat expanded at the base. They decrease in size gradually from the second or third marginal, which is slightly larger than the first, outwards. There is a long, narrow, thin-walled

oesophagus The esophagus (American English), oesophagus (British English), or œsophagus ( archaic spelling) ( see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), colloquially known also as the food pipe, food tube, or gullet, ...

with a single coil; before entering the muscular gizzard it is considerably dilated. A longitudinal strand of muscular tissue runs up its dorsal surface for a short distance from the gizzard. The gizzard is large and it contains three horn-shaped, transversely ridged chitinous plates arranged in a triangle. It is maintained in position by a stout transverse muscle on either side, the proximal end of the muscle being fixed to a constriction in the outer wall of the gizzard. The gizzard contains three large, stout chitinous bodies, which are smooth and heart-shaped at their base on its external surface. Internally they are convex, curved and tapering, with stout, somewhat serrate reversed V-shaped transverse ridges. The intestine after leaving the gizzard bears three small, almost spherical, diverticula, one behind the base of each of the chitinous plates. The wall of the intestine is thin and its structure simple; it has a single closely adpressed bend. Bullacta exarata penis-sack

Reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are al ...

: The male intromittent organ is provided with an elongate chitinous stylet. The penis is enclosed in an oval sack. When extracted therefrom it is an almost cylindrical organ with two coils, or constrictions, in its course, bluntly pointed at the apex and much contracted proximally. Its walls are highly muscular, but all the muscles are longitudinal and there is no circular muscular bulb. Its outstanding feature is the presence of a long, slender, sharply pointed, scimitar-shaped, black, horny stylet with a saddle-shaped base which is sometimes prolonged into a long, sharply pointed spur. In some individuals, however, the spur is completely absent. The female genitalia include a well-developed

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

but no

spermatheca The spermatheca (pronounced : spermathecae ), also called ''receptaculum seminis'' (: ''receptacula seminis''), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, Oligochaeta worms and certain other in ...

. The hermaphrodite gland is small in immature specimen.

Nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

: The

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

closely resembles that of ''

Aliculastrum cylindricum ''Aliculastrum cylindricum'', (common names: cylindrical atys, cylindrical true bubble, silkworm shell), is a species of gastropods belonging to the family Haminoeidae. Description The length of the shell reaches . (Described as ''Bulla elo ...

''.

Ecology

The habitat for this species includes intertidal flats, including the

supratidal zone The supralittoral zone, also known as the splash zone, spray zone or the supratidal zone, sometimes also referred to as the white zone, is the area above the spring high tide line, on coastlines and estuaries, that is regularly splashed, but not s ...

and subtidal zone. ''Bullacta exarata'' is a

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

species. Its life cycle has been extensively studied: * Vitellogenesis (Ying & Yang, 2001) * Oogenesis (Ying, 2002) * Spermatogenesis (Ying et al., 2002) * Reproductive system (Ying et al., 2002) * Spermatozoa (Ying et al., 2004). ''Bullacta exarata'' feeds on

diatoms A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

. It is an important consumer in the

tidal flat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...

ecosystem.

Bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

identified in the

digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

of ''Bullacta exarata'' include the genera '' Photobacterium'', ''

Bacillus ''Bacillus'', from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-sh ...

'', ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...

'', ''

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, which have a characteristic curved-rod (comma) shape, several species of which can cause foodborne infection or soft-tissue infection called Vibriosis. Infection is commonly associated with eati ...

'', some genera from the family

Enterobacteriaceae Enterobacteriaceae is a large family (biology), family of Gram-negative bacteria. It includes over 30 genera and more than 100 species. Its classification above the level of Family (taxonomy), family is still a subject of debate, but one class ...

and others. According to the measurement of hygienic indicator bacteria ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

'' in 2001, the meat of ''Bullacta exarata'' meets national standards (3 cells of ''Escherichia coli'' in one gram of fresh meat) in

Shanghai Shanghai, Shanghainese: , Standard Chinese pronunciation: is a direct-administered municipality and the most populous urban area in China. The city is located on the Chinese shoreline on the southern estuary of the Yangtze River, with the ...

province and in most of

Zhejiang ) , translit_lang1_type2 = , translit_lang1_info2 = ( Hangzhounese) ( Ningbonese) (Wenzhounese) , image_skyline = 玉甑峰全貌 - panoramio.jpg , image_caption = View of the Yandang Mountains , image_map = Zhejiang i ...

province.

UNEP The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the Declaration of the United Nati ...

, Qu J., Xu Z., Long Q., Wang L., Shen X., Zhang J. & Cai Y. (2005)
''East China Sea, GIWA Regional assessment 36.''

University of Kalmar Linnaeus University (LNU) () is a state university in the Swedish historical province (''landskap'') Småland, with campuses located in Växjö and Kalmar. Linnaeus University was established in 2010 by a merger of former Växjö University a ...

, Kalmar, Sweden. 81 pp. + annexes. page 29,

Heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

in the tissues of ''Bullacta exarata'' from the

Yangtze The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the third-longest in the world. It rises at Jari Hill in the Tanggula Mountains of the Tibetan Plateau and flows including Dam Qu River the longest source of the Yangtze, i ...

Estuary were measured by Lu et al. in 2001. In Shanghai, the coast is seriously polluted and measured pollutants in the meat of ''Bullacta exarata'' were in 2003 as follows: * 20.70 mg of

petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...

hydrocarbons in one kg of wet weight (exceeds grade I of biological standard) * 13.10 mg of

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

in one kg of wet weight * 33.60 mg of

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

in one kg of wet weight (exceeds grade II of biological standard)

Human use

''Bullacta exarata'' is a commercially important mollusc in eastern China. Common names in

Mandarin Chinese Mandarin ( ; zh, s=, t=, p=Guānhuà, l=Mandarin (bureaucrat), officials' speech) is the largest branch of the Sinitic languages. Mandarin varieties are spoken by 70 percent of all Chinese speakers over a large geographical area that stretch ...

include Tutie () and Niluo (). It is exported as a food source to Hong Kong, Macau, Taiwan and to

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

. It is also used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...

and there were isolated various compounds with pharmacological activities from ''Bullacta exarata''. Mass mortalities of ''Bullacta exarata'' in Zhejiang in 1995 caused economic losses. The species is being cultivated in

mariculture Mariculture, sometimes called marine farming or marine aquaculture, is a branch of aquaculture involving the cultivation of marine organisms for food and other animal products, in seawater. Subsets of it include ( offshore mariculture), fish fa ...

, especially in

Province, where there was a cultivated area of 8,000 ha in 1999. For example, ''Bullacta exarata'' was the main farming species at the farming area of about 10 100 mu (6.73266 km²) in the

Cixi City Cixi (), alternately romanized as Tzeki, is a county-level city under the jurisdiction of the sub-provincial city of Ningbo, in northeastern Zhejiang province, China. As of the 2020 census, its population was 1,829,488. Its urban agglomeration b ...

, with an estimated annual output of 15 million RMB.People's Republic of China, Ningbo Municipal Government, The World Bank (2005)
"Ningbo Water Environment Project Design Review And Advisory Services Environmental Assessment Volume 2: Summary EA"
accessed 17 December 2010. ''Bullacta exarata'' has high

nutrition Nutrition is the biochemistry, biochemical and physiology, physiological process by which an organism uses food and water to support its life. The intake of these substances provides organisms with nutrients (divided into Macronutrient, macro- ...

value. There is high amount of

omega-3 fatty acid Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their ...

s in the canned meat of ''Bullacta exarata'' (there is 600 mg of

eicosapentaenoic acid Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega−3 fatty acid. In physiological literature, it is given the name 20:5(''n''−3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid wi ...

in 100 g of meat).Siriamornpun S., Bhulaidok S., Sihamala O., Yang L. F. & Li D. (2006). "Composition of lipids and fatty acids of ''Bullacta exarata''". ''Asia Pacific Journal of Clinical Nutrition'' 15(Supplement 2): 129
PDF
.

References

This article incorporates public domain text from the reference