Bullacta exarata isendemic to coastlines of theSouth andEast China Seas fromHainan to theBohai Sea in north-eastern China,[1][9] the western coast and south coast of Korea[1] and Japan.[10]Anecotype of this snail introduced from further south has becomeinvasive inLaizhou Bay, with population densities of over 160 snails per square meter.[11]
Theshell is bullate, fairly thick, white, spirally striate, with a well-developedperiostracum.[3] There is nospire and noumbilicus.[3] Thecolumella is smooth and simple.[3] Theaperture extends for the whole length of the shell, and is narrower above than below.[3] The apertural lip extends upwards beyond theapex of the shell.[3]
The height of the shell is 8 mm and the width of the shell is 6 mm.[12]
The animal cannot withdraw itself into the shell, which contains the visceral hump only.[3] The cephalic disc is large and slipper-shaped, feebly emarginate on the dorsal surface behind and with a narrow free margin.[3]
The cephalic disc, which is rounded in front, occupies about half of the whole bulk in a contracted state.[3] The edge of themantle is smooth, without processes of any kind.[3] 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.[3] The greater part of the mantle, however, under the shell is colourless and transparent.[3] The foot is short, truncate before and behind, and with theepipodia (in much contracted specimens) apparently not well developed.[3] The eyes are minute and quite invisible on the surface.[3] Theeyespots are deeply sunk in the tissues.[3] The gill, which is situated far back on the right side, is large and consists of a considerable number of fleshly lobes.[3]
Drawing of one row of teeth in theradula ofBullacta exarata. C - central tooth, L - lateral tooth, 1-12 - marginal teeth.
Digestive system: The mouth is a minute transverse slit in the front of the cephalic disc.[3] Thejawss are large, but imperfectly cornified.[3] The jaws are angular and minutely, irregularly serrate.[3] They are composed of numerous minute prismatic rods.[3] On the margin many of these rods are transverse and project slightly, forming a minute serration.[3] The radular sack is small.[3] Theradula has the formula 12.1.1.1.12.[3] The central tooth is a simple flat triangular plate.[3] 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.[3] The marginal teeth are slender, elongate, curved rod-like bodies somewhat expanded at the base.[3] They decrease in size gradually from the second or third marginal, which is slightly larger than the first, outwards.[3]
There is a long, narrow, thin-walledoesophagus with a single coil; before entering the muscular gizzard it is considerably dilated.[3] Alongitudinal strand of muscular tissue runs up its dorsal surface for a short distance from the gizzard.[3] The gizzard is large and it contains three horn-shaped, transversely ridgedchitinous plates arranged in a triangle.[3] 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.[3] The gizzard contains three large, stout chitinous bodies, which are smooth and heart-shaped at their base on its external surface.[3] Internally they are convex, curved and tapering, with stout, somewhat serrate reversed V-shaped transverse ridges.[3] The intestine after leaving the gizzard bears three small, almost spherical, diverticula, one behind the base of each of the chitinous plates.[3] The wall of the intestine is thin and its structure simple; it has a single closely adpressed bend.[3]
Drawing of penis-sack ofBullacta exarata.Drawing of penis extracted from the sack.Drawing ofstylet extracted from the penis.
Reproductive system: The male intromittent organ is provided with an elongate chitinousstylet.[3] The penis is enclosed in an oval sack.[3] 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.[3] Its walls are highly muscular, but all the muscles are longitudinal and there is no circular muscular bulb.[3] 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.[3] In some individuals, however, the spur is completely absent.[3]
The female genitalia include a well-developeduterus but nospermatheca.[3] The hermaphrodite gland is small in immature specimen.[3]
According to the measurement of hygienic indicator bacteriaEscherichia coli in 2001, the meat ofBullacta exarata meets national standards (3 cells ofEscherichia coli in one gram of fresh meat) inShanghai province and in most ofZhejiang province.[18]
Bullacta exarata is a commercially important mollusc in eastern China.[7] Common names inMandarin Chinese include Tutie (Chinese:吐铁;pinyin:Tǔtiě) and Niluo (Chinese:泥螺;pinyin:Níluó).[23] It is exported as a food source to Hong Kong, Macau, Taiwan and toSoutheast Asia.[24] It is also used intraditional Chinese medicine and there were isolated various compounds with pharmacological activities fromBullacta exarata.[25]
Mass mortalities ofBullacta exarata in Zhejiang in 1995 caused economic losses.[17] The species is being cultivated inmariculture, especially inZhejiang Province, where there was a cultivated area of 8,000 ha in 1999.[17]
For example,Bullacta exarata was the main farming species at the farming area of about 10 100mu (6.73266 km2) in theCixi City, with an estimated annual output of 15 millionRMB.[26]
^abcdYe S.-F. & Lu J.-J. (2001) "Analysis on the spatial distribution ofBullacta exarata (Mollusca: Gastropoda: Atyidae) population in Yangtze River Estuary, China".Zool Res22: 131-136.ISSN0254-5853.abstract.
^Pilsbry H. A. (1895).Manual of Conchology, structural and systematic, with illustrations of the species. Polyplacophora, (Chitons.) Acanthochitidae, Cryptoplacidae and appendix. Tectibranchiata.15:page 362-363.plate 40, figure 97.
^(in Chinese) Ying X. P & Yang W. X. (2001). "Mitochondrial changes during vitellogenesis in oocytes ofBullacta exarata".Zoological Research22(5): 379-382.PDFArchived July 7, 2011, at theWayback Machine.
^(in Chinese) Ying X. P. (2002). "Study on ultrastructure of oogenesis ofBullacta exarata".Developmental and Reproductive Biology11(1): 29-36.
^(in Chinese) Ying X. P., Jiang N. C. & Yang W. X. (2002). "Ultrastructural studies on spermatogenesis ofBullacta exarata".Zoological Research23(5): 400-404.PDFArchived July 7, 2011, at theWayback Machine.
^(in Chinese) Ying X. P., Chen N., Hua E. C., Fu L. & Wang X. (2002). "Histological studies on the reproductive system ofBullacta exarata".Donghai Marine Science20(3): 24-31.
^Lu, J.; He, W.; Zhou, K.; Tang, Y.; Ye, S.; Sun, P. (2001). "Behavior of Zn, Cu, Pb and Cd in biota of Yangtze Estuary".Science in China Series B: Chemistry.44 (1):165–172.doi:10.1007/BF02884823.
^abcSiriamornpun S., Bhulaidok S., Sihamala O., Yang L. F. & Li D. (2006). "Composition of lipids and fatty acids ofBullacta exarata".Asia Pacific Journal of Clinical Nutrition15(Supplement 2): 129.PDFArchived August 11, 2011, at theWayback Machine.
Ge B.-M., Bao Y.-X., Cheng H.-Y. & Zheng X. (2006). "Population Distribution ofBullacta exarata in Cixi Shore, Southern Hangzhou Bay in Summer".Fisheries Science.ISSN1003-1111.abstract.
Gu, X.; You, Z.; Wang, Y.; Ding, W.; Xu, H. (1997). "Preliminary study on growth of mud snailBullacata exarata".Journal of Zhejiang College of Fisheries.16 (1):6–11.
(in Chinese) Li S.-g. (2005). "The Biology ofBullacta exarata (泥螺的生物学)".Reservoir Fisheries4: 42-54.
(in Chinese) Liu H. (2003). "Technology for aquiculture ofBullacta exarata in benefit ponds in salt fields (盐场效益池泥螺养殖技术初探)".Jiangsu Province Salt Science & Technology3: 15-16.
(in Chinese) Wang Y., You Z., Zuo H. & Wang G. (2003). "Study on Ecological Habit of Mud Slug,Bullacta exarata (养殖泥螺生态习性研究)".Journal of Ningbo University (Natural Science & Engineering Edition)3: 240-244.
(in Chinese) Wang Y.-n. & Yu H. (2006). "Techniques for Culture ofBullacta exarata in Retaining Water Intertidal Zone (泥螺的滩涂蓄水养殖技术)".Fisheries Science & Technology Information5: 238-240.
(in Chinese) Xu P. (2003). "A Study on Breeding and Enhancement Technique ofBullacta exarata (Philipi) (泥螺Bullacta exarata(Philippi)育苗及增养殖技术探讨)".Modern Fisheries Information4: 24-26.
Ye S.-F. & Lu J.-J. (2001). "Characteristics and ecological significance of the developing population ofBullacata exarata (Philippi, 1848) (Mollusca: Gastropoda, Atyidae) in the Yangtze estuary, China".Resources and Environment in the Yangtze Basin10(3): 216-222.ISSN1004-8227.abstract.
(in Chinese) You Z., Wang Y. & Ding W. (1994). "Effects of environmental factors onBullacta exarata (Gastropoda, Scaphandridae) at different developmental stages".Journal of Zhejiang College of Fisheries13(2): 79-85.
(in Chinese) Zhang Z. (2001). "Technology Exploration of PickledBullacta exarata (腌制泥螺的工艺探讨)".Journal of Shaoxing College of Arts and Sciences (Natural Science)7: 71-73.
Zhu S.-Y., Wu Y.P., Sheng H. D. et al. (2008). "Artificial hybridization and juvenile nursery ofBullacta exarata".J. Zhejiang. Ocean. Univ.1: 32-36. Natural Science.
(in Chinese) Zuo H., Wang Y., Xu J. & Wang G. (2005). "Key Technique onBullacta exarata Culture (泥螺生态系管养的技术要点)".Fisheries Science1: 29-30.
