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The biomineralization mechanism of mollusc shell has been studied for a long time, but there is a lack of understanding about the relationship between the shell formation in vitro and the signaling system in vivo. In this study, we cloned a novel shell matrix protein gene (hc-temptin), which only be characterized as a water-borne protein pheromone of molluscs in previous studies, from the freshwater mussel Hyriopsis cumingii. By bioinformatics analysis we found that temptin was a gene unique to the clade Lophotrochozoa, and it exists in all mollusc taxa except Cephalopoda. The current data supported the premise that temptin was generated in the early emergence of molluscs and that it maintained a high mutation rate to evolve relative independently. The specificity of hc-temptin expression in the mantle tissue suggests its potential to participate in biomineralization. Its sequence contained typical Ca2+ binding sites. Our experiments involving the pearl formation process, damaged shell repair process, and RNAi experiment showed that hc-temptin was a shell matrix protein that plays an important role in formation of the prismatic layer. The results of this study provided new insights about the origin of the temptin gene and its role in molluscs.

The study of the Neolithic period in the Lake Eyasi Basin was dominated by attempts to formulate the area’s chronology, mobility, settlement patterns, subsistence, and cultural capabilities of Neolithic people as attested by domesticated animals, pottery, and lithic artefacts. Occasionally, studies on molluscs were mentioned, but rarely described in detail. Neolithic sites across the Lake Eyasi Basin have yielded remains of both terrestrial (gastropods) and freshwater mollusc shells (mussels). The abundance of mollusc shell remains in the archaeological records of the Lake Eyasi Basin have played a great role in chronological settings, mobility and community integrations, studies of settlement patterns, and other analyses. Mollusc remains have often been widely interpreted as a food supplement to other reliable food resources such as meat, vegetables and fish. Archaeological excavations and detailed analysis of the shells from Mumba rock shelter, Jangwani 3 and Laghangasimjega 2 have shown that molluscs played different roles. They were effectively used in tool manufacturing, as practical implements for handling objects, as scraping tools, as harpoons for fishing weapons, and sometimes for symbolism and in rituals. Terrestrial and freshwater molluscs coexisted in the Lake Eyasi Basin and were utilised equally by the Neolithic people during the Mid-Holocene period. Keywords: Mollusc shells; Neolithic; Lake Eyasi Basin; Northern Tanzania

The preservation status of the mollusc shell accumulation of sandy barriers at the Amvrakikos Gulf lagoon complex was studied. Taphonomic shell analysis of dead mollusc depositions was undertaken in the summer of 2016 at Amvrakikos lagoon complex within the Tsoukalio and Logarou sandy barriers, which showed significant differences among the major abundant bivalve species of Cerastoderma glaucum and Polititapes aureus. Both hydrodynamic transport and differential exposure to environmental conditions differ among the accumulated shells depositions of the lagoonal sandy barriers. The heavier and more durable shells of C. glaucum are frequently found concentrated at the Tsoukalio lagoon accumulations and show a higher intensity of fragmentation whereas at Logarou lagoon the bioerosion and abrasion is more intense. On the other hand, the lighter, thinner, and thus more fragile shells of P. aureus show higher concentration and intensity of fragmentation and bioerosion at Logarou lagoon sandy barriers. The continuous deposition of shells at Tsoukalio lagoonal sandy barriers, contrary to the long-term deposition at Logarou lagoon, explains the different types of accumulations among the lagoons which are attributed to the geomorphology of the sandy shores as well as the morphological characteristics of the different shells.

Many biological structures use liquid crystals as self-organizing templates for their formation. We review and analyse evidence that the crossed-lamellar biomineral microstructure of mollusc shells may be formed from such a liquid-crystal precursor., We acknowledge funding from projects CGL2017-85118-P and FIS2016-77692-C2-2-P of the Spanish Ministerio de Ciencia e Innovación, the Unidad Científica de Excelencia UCE-PP2016-05 of the University of Granada and the Research Group RNM363 of the Junta de Andalucía.

This article highlights the importance of the addition of Mollusc shell (MS) particles, as bio-filler, on the tribological behavior of high-density polyethylene (HDPE) matrix. The elaborated biocomposites are intended to be used as an orthopedic replacement biomaterial. Different mass content of MS (0, 5, 10, 15 and 20 wt. %) have been added to the HDPE matrix. FTIR analysis, crystallinity rate and Rockwell hardness of different bio-composites were performed. A reciprocating pin-on-disc tribometer was used to fulfil dry wear tests. FTIR analysis showed that the presence of MS particles improved the crystallinity of the HDPE phase. Adding to that, it was found that MS improved the hardness, friction coefficient and wear resistance of the HDPE polymer. In fact, by adding 5 wt. % of MS to the HDPE, good tribological properties were achieved. Scanning Electron Microscopy (SEM) was performed to investigate the wear morphology of biocomposites under dry condition. SEM images showed that the morphology of the worn surfaces had been improved by the addition of MS to the polymer. Finally, a wear scenario was proposed.

Long-term investigations devoted mostly to the Eurasian Arctic sedimentary deposits have provided dated climatic sequence within the Late Pleistocene period. Most of the dates (ca. 315) were obtained by electron spin resonance (ESR) method on marine mollusc remains taken directly from transgressive marine sedimentary deposits. Here, it is shown that the climatic signature revealed in the studied sedimentary sequences can be compared by proxy- and chronologic correlation with the climatic signals recorded in different parts of the continent from deposits of marine, freshwater, and terrestrial origin. The resulting climate-chronostratigraphic record allow the last interglacial to be placed approximately between 145–140 ka and 70 ka with concentration of overwhelming majority of the warm climate-related dates (ca. 82%) in the second half of Marine Isotope Stage (MIS) 5 in the time range between 110 and 70 ka. This evidence coincides with integrative multidisciplinary results derived from the south-eastern coast of the Gulf of Finland. They show unambiguously that the second half of the MIS 5 sequence, at least between ca. 94 ka and 71 ka, reflects the fully interglacial character of the studied deposits. The climate-chronostratigraphic record within MIS 3 displays a sequence of three successive palaeoenvironmental events (59.0–52.0 ka, 47.5–40.0 ka and 32.4–24.8 ka), which are interpreted as the consequence of large-scale climate amelioration during which marine sedimentation occurred on palaeo-shelves what is now dry land. The consistency of the parallel comparative dating results obtained in this study by different methods, both the numerical and relative, exemplify the potential of palaeodosimetric dating methods mainly used in this study — mollusc shell-based electron spin resonance (ESR) and feldspar-based infrared optically stimulated luminescence (IR-OSL) — to chronologically organize the sequence of the Late Pleistocene palaeoenvironmental events, and to improve understanding of the palaeoenvironmental evolution during this period.

The shells of marine invertebrates can serve as high-resolution records of oceanographic and atmospheric change through time. In particular, oxygen and carbon isotope analyses of nearshore marine calcifiers that grow by accretion over their lifespans provide seasonal records of environmental and oceanographic conditions. Archaeological shell middens generated by Indigenous communities along the Northeast Pacific coast contain shells harvested over multiple seasons for millennia. These shell middens, as well as analyses of archival and modern shells, have the potential to provide multi-site, seasonal archives of nearshore conditions throughout the Holocene. A significant volume of oxygen and carbon isotope data from archaeological shells exists, yet is separately published in archaeological, geochemical, and paleoceanographic journals and has not been comprehensively analyzed to examine oceanographic change over time. Here, we compiled a database of previously published oxygen and carbon isotope data from archaeological, archival, and modern marine molluscs from the North American coast of the Northeast Pacific (32° N to 50° N). This database includes oxygen and carbon isotope data from over 550 modern, archaeological, and sub-fossil shells from 8880 years before present (BP) to the present, from which there are 4,845 total δ13C and 5,071 total δ18O measurements. Shell dating and sampling strategies vary among studies (1–118 samples per shell) and vary significantly by journal discipline. Data are from various bivalves and gastropod species, with Mytilus spp. being the most commonly analyzed taxon. This novel database can be used to investigate changes in nearshore sea surface conditions including warm-cool oscillations, heat waves, and upwelling intensity, and provides nearshore calcite δ13C and δ18O values that can be compared to the vast collections of offshore foraminifera calcite δ13C and δ18O data from marine sediment cores. By utilizing previously published geochemical data from midden and museum shells rather than sampling new specimens, future scientific research can reduce or omit the alteration or destruction of culturally valued specimens and sites. The data set is publicly available through PANGAEA at https://doi.org/10.1594/PANGAEA.932671 (Palmer et al., 2021).

Mollusc shell stable isotopes are commonly used to reconstruct past environmental conditions. However, despite being abundant components of natural and anthropogenic fossil accumulations, the geochemical composition of mussel shells ( Mytilus spp.) has rarely received attention in palaeoenvironmental studies. This study tests the suitability of oxygen isotopes (δ18Os) of Mytilus galloprovincialis as palaeothermometer. For 1 year, mussels and water samples were collected twice a month from Berria Beach, in Northern Spain. The geochemical data of the shells indicate that water temperatures can be reconstructed with an average offset of 1.2 ± 0.7°C with respect to the measured values. Furthermore, no prolonged shell growth cessations are observed. These results validate M. galloprovincialis as reliable recorders of seasonal water temperature fluctuations, supporting their use in palaeoenvironmental studies. In addition, further shell and water collections were carried out in the upper and lower areas of a nearby estuary. The geochemical analyses of these shells were aimed to test whether oxygen and carbon stable isotopes (δ13Cs) may be used as novel proxies to identify the shell provenance at local scale. The results show that the δ18Osversus δ13Cscorrelation direction varies along the coast–upper estuary geographical gradient, suggesting it to be a potential new proxy to distinguish between marine and estuarine mussel specimens.

Mollusc aquaculture is a high-value industry that is increasing production rapidly in Europe and across the globe. In recent years, there has been discussion of the potential wide-ranging environmental benefits of this form of food production. One aspect of mollusc aquaculture that has received scrutiny is the production of calcareous shells (CaCO3). Mollusc shell growth has sometimes been described as a sink for atmospheric CO2, as it locks away carbon in solid mineral form. However, more rigorous carbonate chemistry modelling, including concurrent changes in seawater pCO2, pH, dissolved inorganic carbon, and total alkalinity, shows that calcification is a net CO2 source to the atmosphere. Combined with discussions about whether mollusc respiration should be included in carbon footprint modelling, this suggests that greater in-depth understanding is required before shellfish aquaculture can be included in carbon trading schemes and footprint calculations. Here, we show that regional differences in the marine carbonate system can alter the amount of CO2 released per unit CaCO3 formation. Our carbonate chemistry modelling shows that a coastal mussel farm in southern Portugal releases up to ~0.290 g of CO2 per g of CaCO3 shell formed. In comparison, an identical farm in the coastal Baltic Sea would produce up to 33% more CO2 per g of CaCO3 (~0.385 g-CO2·(g-CaCO3)−1). This spatial variability should therefore also be considered if mollusc aquaculture is to be included in future carbon trading schemes, and in planning future expansion of production across the industry.

Background Although the apple snail Pila globosa is used as indicator species for human consumption locally and as fish feed, research on it in general is very scanty. It is used in food industry, in aquaculture as fish bait and used as food in many regions of India and many other countries, but research on it has been started in the 1970s. Only 40 articles are available on this organism in PubMed indicating an urgent need of basic research on it especially work on its spatiotemporal morphometry Therefore, sampling of P. globosa was done from different parts of India in different seasons (summer, winter and rainy), and different morphometric studies were performed on this organism to draw baseline information. Analysis was conducted to study morphometry, the relationship between shell length and the weight and relative condition factor of Indian apple snail Pila globosa collected from five zones (east, west, north, south and centre) of India during 2018–2019 year. Results The shell length (SL) (46.5 ± 13.33), shell width (SW) (40.22±11.5 mm), spire length (SPL) (2.99±0.15 mm), base length (BL) (12.53±2.94 mm), aperture length (AL) (21.95±4.36 mm), aperture width (AW) (2.74±0.47 mm) and shell weight (WT) (31.08±13.76 g) were observed to be varied among the individual sampled across India. Different relationships for SL/SW (Log SW=0.9889 Log SL + 0.9444), SL/SPL (Log SPL = 0.1452 Log SL+0.3815), SL/BL (Log BL=0.7789 Log SL+0.5814), SL/AL (Log AL= 0.6518 Log SL+0.9111) and SL/AW (Log AW=0.4475 Log SL+0.1422) were observed by considering shell length as basic index. The relationship between shell length and shell weight was found to be Log WT=2.0263 Log SL+0.1098. The relative condition factor revealed uninterrupted and good environmental condition observed for apple snails. A negative allometric growth pattern was observed from the length–weight relationship. Conclusion The environments of apple snail in India are not contaminated, and the results can be used as baseline data in aquaculture for model analysis and can be used as a reference for drawing relationship among different morphometric indices of P. globosa in India, as there is no such information available on it. The data can also be used for mass scale production of P. globosa for consumption by human and use in aquatic industries as fish feed.

Marine aquaculture releases mollusc shell debris which can accumulate on the seabed. Due to its low degradability, mollusc shell debris becomes integrated into the sediment, modifying both its structure and associated biogeochemical processes. These changes are expected to influence the biological assemblages within the sediment, which play a key role in the biogeochemical processes due to bioturbation. We performed an in-situ experiment to test the effects of mollusc shell-hash on the bioturbation capacity of the macrofaunal assemblages within the sediments affected by marine aquaculture. The aquaculture facilities chosen were a fish farm in an oligotrophic area of the Mediterranean over a sandy sediment, and a mussel farm in the Atlantic located in an estuary over silty sediment. Mollusc shell-hash promoted macrofaunal assemblages with a high bioturbation potential, regardless of the influence of aquaculture. Nevertheless, in the sediment from the mussel-farm, the shell-hash did not have a marked effect on the macrofaunal assemblages. The effect of shell-hash on promoting macrofaunal communities with a high bioturbation potential capacity is therefore dependent on the existing environmental conditions in the area, including the natural organic matter input and grain size of the sediment. Shell-hash could be used a strategy to improve the ecosystem function of sediments as a circular economy-oriented management practice. This research was funded by the project CGL2015-70136-R from the Spanish National Agency for Research (MINECO/FEDER). CS was funded by the University of Alicante (Ref. UATALENTO 17-11).

Recent technical innovations are revealing surprising patterns in mollusc shell pigmentation, such as an unexpectedly modest role for melanins and rapid divergences in the mix of pigments used to achieve similar colour patterns. The elucidation of the molecular genetic basis of shell pigmentation has been slow, probably because of the high genome complexity of gastropods and bivalves. Recent work within the old field of evolutionary ecology of shell pigmentation allows a greater role for the analysis of large-geographic-scale patterns (sometimes employing citizen-science data), as well as experimental field studies. However, the field remains dominated by land snails as model organisms, while colour pattern evolution in marine gastropods and bivalves, particularly those not exposed to visual predators, remains mysterious.

Rates of peptide bond hydrolysis and other diagenetic reactions are not favourable for Mesozoic protein survival. Proteins hydrolyse into peptide fragments and free amino acids that, in open systems such as bone, can leach from the specimen and be further degraded. However, closed systems are more likely to retain degradation products derived from endogenous proteins. Amino acid racemisation data in experimental and subfossil material suggests that mollusc shell and avian eggshell calcite crystals can demonstrate closed system behaviour, retaining endogenous amino acids. Here, high-performance liquid chromatography reveals that the intra-crystalline fraction of Late Cretaceous (estimated ~80 Ma) titanosaur sauropod eggshell is enriched in some of the most stable amino acids (Glx, Gly, Ala, and possibly Val) and those that racemise are fully racemic, despite being some of the slowest racemising amino acids. These results are consistent with degradation trends deduced from modern, thermally matured, sub-fossil, and ~3.8 Ma avian eggshell, as well as ~30 Ma calcitic mollusc opercula. Selective preservation of certain fully racemic amino acids, which do not racemise in-chain, along with similar concentrations of free versus total hydrolysable amino acids, likely suggests complete hydrolysis of original peptides. Liquid chromatography-tandem mass spectrometry supports this hypothesis by failing to detect any non-contamination peptide sequences from the Mesozoic eggshell. Pyrolysis-gas chromatography-mass spectrometry reveals pyrolysates consistent with amino acids as well as aliphatic hydrocarbon homologues that are not present in modern eggshell, suggestive of kerogen formation deriving from eggshell lipids. Raman spectroscopy yields bands consistent with various organic molecules, possibly including N-bearing molecules or geopolymers. These closed-system amino acids are possibly the most thoroughly supported non-avian dinosaur endogenous protein-derived constituents, at least those that have not undergone oxidative condensation with other classes of biomolecules. Biocrystal matrices can help preserve mobile organic molecules by trapping them (perhaps with the assistance of resistant organic polymers), but trapped organics are nevertheless prone to diagenetic degradation even if such reactions might be slowed in exceptional circumstances. The evidence for complete hydrolysis and degradation of most amino acids in the eggshell raises concern about the validity of reported polypeptide sequences from open-system non-avian dinosaur bone and other Mesozoic fossils.

The diversity of Hippothoidae (Bryozoa, Cheilostomata) in New Zealand is increased from 12 named species to 17 and the number of genera from three to five. New species are recognised in the genera Antarctothoa, Hippothoa, Jessethoa n. gen. and Neothoa (newly discovered in New Zealand waters). A new species of Plesiothoa from New South Wales is also described. Collectively, the new taxa encrust a range of substrata (a catenicellid bryozoan, brown and red macroalgae, rock and mollusc shell). The status of two existing species is changed—Hippothoa divaricata pacifica Gordon, 1984 is raised to full species, and Hippothoa watersi Morris, 1980 is used for putative Hippothoa flagellum in New Zealand. New data are given for these species and Hippothoa peristomata Gordon, 1984, and little-known Antarctothoa buskiana (Hutton, 1873) and Antarctothoa cancer (Hutton, 1873) are illustrated by scanning electron microscopy for the first time.

8 pages, 4 figures, 1 table, supplementary data https://doi.org/10.1016/j.zool.2020.125778, Gastropod shells may present large spines and sharp shapes that vary according to environmental, taxonomic, and evolutionary factors. In these cases, classic morphometric methods used to study shell contour might not provide a clear representation of morphological shell based on angular decomposition of contour. The present study analyzed and compared for the first time the robustness of the contour analysis using wavelet transformed and Elliptic Fourier descriptors for gastropod shells including enlarged spines. For that, we analyzed two geographical and ecological separated populations of Bolinus brandaris from the NW Mediterranean Sea. Results showed that contour analysis of gastropod shells with enlarged spines can be analyzed using both methodologies, but the wavelet analysis provided a better local discrimination. From an ecological perspective, shells with spines of different sizes were observed in both localities suggesting a wide plasticity of the species, This paper is a result of the research project “Evaluación y seguimiento del Plan de Gestión de Dragas para Embarcación”, ref. AG-2016-233, funded by the Department of Agriculture, Livestock, Fisheries and Food of the Government of Catalonia (Spain), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

The purpose of this study is to improve the recruitment of flat oyster larvae, an endangered species, by means of a specific marine infrastructure made of concrete. This work aims to develop and optimize concrete formulations by varying the type of cement and introducing shellfish by-products into their composition and determine which concrete formulation is the most sustainable to marine organism colonization. Indeed, it is essential to obtain a sustainable concrete submitted to aggressive marine environment (chloride ions diffusion and bio-colonisation). Four concrete formulations were tested with two types of cements (CEMII and CEMV) and with or without the incorporation of shell aggregates. The durability of these materials was tested after 3 months of immersion in the Rance of Dinard (France). It appears from this study that the CEMII concrete exhibits a good mechanical resistance independently of the presence of shell, after immersion in situ. This concrete also shows better resistance to chloride ions diffusion than CEMV. However, CEMV possess larger compressive strengths than CEMII, and mollusc shells incorporation does not decrease this strength as much as for CEMII. Shell incorporation in the concretes has an effect on strength, chloride penetration and porosity which depend on the used cement and seawater.

(IF 3.41; Q1); International audience; Bioclastic particles derived from mollusc shell debris can represent a significant fraction of sandy to gravelly sediments in temperate and cool‐water regions with high carbonate productivity. Their reworking and subsequent transport and deposition by waves and currents is highly dependent on the shape and density of the particles. In this study, the hydrodynamic behaviour of shell debris produced by eight mollusc species is investigated for several grain sizes in terms of settling velocity (measurements in a settling tube) and threshold of motion under unidirectional current (flume experiments using an acoustic profiler). Consistent interspecific differences in settling velocity and critical bed shear stress are found, related to differences in shell density, shell structure imaged by scanning electron microscopy and grain shape. Drag coefficients are proposed for each mollusc species, based on an interpolation of settling velocity data. Depending on the shell species, the critical bed shear stress values obtained for bioclastic particles fall within or slightly below empirical envelopes established for siliciclastic particles, despite very low settling velocity values. The results suggest that settling velocity, often used to describe the entrainment of sediment particles through the equivalent diameter, is not a suitable parameter to predict the initiation of motion of shell debris. The influence of the flat shape of bioclastic particles on the initiation of motion under oscillatory flows and during bedload and saltation transport is yet to be elucidated.

Radix sp., Gyraulus sp. and Pisidium sp. are aquatic mollusc taxa. Although their fossil shells occur widely in dammed palaeo-lake sediments in the Yarlung Tsangpo valley in Tibet, their hydrochemical and hydrological implications are not fully understood. Moreover, vital effects on the trace element and stable isotope composition of the aragonite shells of these molluscs are unclear. We measured the values of δ13Cshell, δ18Oshell, Sr/Cashell and Mg/Cashell of the fossil shells of Radix sp., Gyraulus sp., and Pisidium sp. collected from the dammed lake sedimentary sequences at Xigaze and Lhainxiang in Tibet, with the aim of reconstructing the palaeo-hydrochemistry and palaeo-hydrology of the dammed palaeo-lake. The results show that the values of δ18Owater, Sr/Cawater and electrical conductivity (EC) of the dammed palaeo-lake water are higher than those of the modern Yarlung Tsangpo River water. Nevertheless, the dammed palaeo-lake still exhibited a through-flow status, together with freshwater characteristics. The values of δ18Oshell and δ13Cshell of Gyraulus sp. and Radix sp. have a positive relationship, but their ratios of Sr/Cashell and Mg/Cashell are not correlated. Moreover, δ18Oshell in the Radix sp. shells is ~2.97 ‰ more enriched and has a stronger relationship with δ18Owater than is the case for shells of Gyraulus sp. The values of δ18Oshell and δ13Cshell of Pisidium sp. are similar to those of the shells of Radix sp., and we conclude that the shells of Radix sp. are the most suitable mollusc shell for recording the δ18Owater of the ambient water of water bodies in the Tibetan Plateau.

Animals avoid predator attack in different ways; some carry defensive structures to reduce predation, with the classic example being hermit crabs and their use of a mollusc shell as a portable refugium. During shell selection, various shell characteristics are investigated by the crab to determine their suitability. Here we consider the role of visual cues. Previous research suggests that some hermit crabs are more likely to initially choose a conspicuous shell but also to move to backgrounds against which they are less conspicuous, suggesting a short-term/long-term trade-off. Across experiments in which we manipulated shell and background colour, we show initially that Pagurus bernhardus prefer black shells over white but this preference was lost in the absence of visual cues. We then show that the strength of preference was dependent on background colour. We repeated this last experiment with red and yellow shells against red or yellow backgrounds to investigate whether this preference extended to chromatic hues. A preference for darker (red) shells was expressed, but preference alteration with background was not observed. P. bernhardus therefore discriminate between shells in terms of shell and background colour, and discrimination may be rooted in a preference for darker shaded shells. Postprint

A three-dimensional porous carbon skeleton with hexagonal channels was synthesized by using mollusc shell as the carbon source. The obtained mollusc shell based macroporous carbon material (MSBPC) has high conductivity and is very favorable for use in the electrolyte penetration and electron transfer, making it an excellent carbon substrate for composite electrode materials. After incorporation of MnO 2 nanosheets, the MSBPC/MnO 2 was synthesized and applied in supercapacitors, which exhibited a high specific capacitance of 386 F g −1 at 1 A g −1 with an excellent rate performance (278.7 F g −1 at 10 A g −1 ), and outstanding cycling stability, with a capacitance retention of 83% after 5000 cycles at 20 A g −1 . The good electrochemical performance indicates the high potential of the prepared MSBPC/MnO 2 as a novel supercapacitor electrode material with a high power density, excellent long life cycling, and environmental friendliness.

Understanding environmental conditions faced by hunter-fisher-gatherers during the Pleistocene and Holocene, and interpretation of subsistence strategies, social organisation and settlement patterns, are key topics for the study of past human societies. In this respect, oxygen isotope values (?18O) of mollusc shell calcium carbonate can provide important information on palaeoclimate and the seasonality of shell collection at archaeological sites. In this paper, we tested P. vulgata shells from northern Iberia as a paleoclimate archive through the study of shell oxygen isotope values and sclerochronology of modern samples. Results showed that limpets formed their shells close to isotopic equilibrium, with an average offset between measured and predicted values of 0.36?. This offset is significantly reduced with respect to those reported in previous studies, probably due to the use of highly resolved data on the isotopic composition of the water when calculating predicted values. Despite large intra-specific variability, shell growth patterns of P. vulgata revealed a common pattern of higher growth in spring and a growth cessation/slowdown in summer and winter. The seasonal growth cessation/slowdown did not exceed three months. Therefore, a correct interpretation of the season of shell collection is still possible. Reconstructed seawater temperature exhibited a high correlation with instrumental temperature (R2 =0.68 to 0.93; p b 0.0001). Despite periods of growth cessation/slowdown, mean seawater temperatures and annual ranges were reconstructed accurately. As demonstrated here, seawater temperature can be reconstructed with a maximum uncertainty of ±2.7 °C. Therefore, our study shows that oxygen isotope values from P. vulgate can be used for the reconstruction of paleoclimate and the season of shell collection This research was part of the projects NF100413 (Newton International Fellowship granted to IGZ) and HAR2013-46802-P (funded bythe Spanish Ministry of Economy and Competitiveness, MINECO).

Mollusc shells, beyond the treasure of information inherently conveyed through their morphology and chemical composition also have the capacity to preserve DNA sequences over the long term in their inner structure. This has been clearly demonstrated for the first time in the study published in this issue of Molecular Ecology Resources by Der Sarkissian et al. (2017). With a methodology specifically dedicated to ancient DNA and solid matrices, the authors were able to successfully extract and amplify DNA from marine shells spanning the last 7,000 years. Furthermore, using metagenomic analyses, they could identify important factors affecting DNA recovery. Using reference genomes and sequences in a targeted approach to assign high-throughput sequencing reads, the authors revealed both the presence of endogenous mollusc DNA and a potent pathogen of Manilla clam. Collectively, the results presented in this study open extremely promising research avenues, from palaeogenomics and evolutionary biology to ecological genomics at population and community levels, as well as the opportunity to fine-tune diagnostic tools for conservation and aquaculture purposes. Last but not least, this study also offers exciting perspectives in epigenomics and the evolution of regulatory processes in the context of adaptation to global change. It can be easily expected that the approach developed by Der Sarkissian et al. (2017) will be pursued and extensively investigated in the near future by the scientific community interested in these issues.

This chapter presents a general review of the research on mollusc shell recycling as aggregates in concrete production. The mollusc species studied were oyster, cockle, scallop and mussel. All these shells are similar in composition and their structure is made mainly of calcium carbonate. The use of recycled shell aggregates in concrete produces a reduction of the hardened density and a drop in workability. Also the mechanical properties at 7 and 28 days are negatively affected. This was due to the flaky shape of the aggregates and the presence of the nacre layer of the shells, which reduces bonding and increases porosity.

The adductor muscle scar (AMS) is the fixation point of adductor muscle to the shell. It is an important organicinorganic interface and stress distribution area. Despite recent advances, our understanding of the structure and composition of the AMS remain limited. Here, we report study on the AMS of three bivalves: Mytilus coruscus, Chlamys farreri and Ruditapes philippinarum. Results showed that there were significant differences among their AMS structures. Both M. coruscus and C. farreri were found to have a columnar layer above the nacreous platelet shell structure at the AMS and this layer was more organized in M. coruscus. There was no distinguishable twolayer structure in R. philippinarum. Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) results showed that the AMS was much smoother than the nacreous inner shell in all the three species and the AMS had minor different compositions from the nacreous shell layer. SDS-PAGE (sodium dodecyl-sulfate polyacrylamide gel electophoresis) study of the proteins isolated from the interface indicated that there was a 70 kDa protein which seemed to be specifically located to the highly organized columnar AMS structure in Mytilus coruscus. Further analysis of this protein showed it contained high level of Asx (Asp+Asn), Glx (Glu+Gln) and Gly. The special structure and composition of the AMS might play important roles in the stability, adhesion and function at this stress distribution site.

Raised atmospheric emissions of carbon dioxide (CO2) result in an increased ocean pCO2 level and decreased carbonate saturation state. Ocean acidification potentially represents a major threat to calcifying organisms, specifically mollusks. The present study focuses on the impact of elevated pCO2 on shell microstructural and mechanical properties of the bivalve Cerastoderma edule. The mollusks were collected from the Baltic Sea and kept in flow-through systems at six different pCO2 levels from 900 μatm (control) to 24,400 μatm. Extreme pCO2 levels were used to determine the effects of potential leaks from the carbon capture and sequestration sites where CO2 is stored in sub-seabed geological formations. Two approaches were combined to determine the effects of the acidified conditions: (1) Shell microstructures and dissolution damage were analyzed using scanning electron microscopy (SEM) and (2) shell hardness was tested using nanoindentation. Microstructures of specimens reared at different pCO2 levels do not show significant changes in their size and shape. Likewise, the increase of pCO2 does not affect shell hardness. However, dissolution of ontogenetically younger portions of the shell becomes more severe with the increase of pCO2. Irrespective of pCO2, strong negative correlations exist between microstructure size and shell mechanics. An additional sample from the North Sea revealed the same microstructural-mechanical interdependency as the shells from the Baltic Sea. Our findings suggest that the skeletal structure of C. edule is not intensely influenced by pCO2 variations. Furthermore, our study indicates that naturally occurring shell mechanical property depends on the shell architecture at μm-scale.

Climate change and ocean acidification are likely to have a profound effect on marine molluscs, which are of great ecological and economic importance. One process particularly sensitive to climate change is the formation of biominerals in mollusc shells. Fundamental research is broadening our understanding of the biomineralization process, as well as providing more informed predictions on the effects of climate change on marine molluscs. Such studies are important in their own right, but their value also extends to applied sciences. Biominerals, organic/inorganic hybrid materials with many remarkable physical and chemical properties, have been studied for decades, and the possibilities for future improved use of such materials for society are widely recognised. This article highlights the potential use of our understanding of the shell biomineralization process in novel bio-inspired and biomimetic applications. It also highlights the potential for the valorisation of shells produced as a by-product of the aquaculture industry. Studying shells and the formation of biominerals will inspire novel functional hybrid materials. It may also provide sustainable, ecologically- and economically-viable solutions to some of the problems created by current human resource exploitation. (C) 2016 Elsevier B.V. All rights reserved.

Mollusc shells are renowned for their mechanical strength and toughness. To better understand the mineralization process of the shell, structure of the body whorl and base of Conus litteratus (Conus shell) were in detail investigated by using scanning electron microscopy. Three-point bending tests were taken to demonstrate that each layer of crossed-lamellar structures is indispensable to enhance the whole strength of the shells. The results show that the conch shell is composed of hierarchical structure from nano scale to macro scale, and the basic constituent is long rod-shaped aragonite. Different positions of the shell have varied structures, and the base is more complicated than the body whorl. The mechanical properties of Conus are highly anisotropic and the arrangement of middle layer has a great influence on the bending strength. The outer and inner layers are very thin but play a protective role for the middle layer.

To infer the early evolution of mollusc shell microstructures we must know the most ancient fossil record of molluscs. Fortunately the shells of many early molluscs are preserved via internal coatings and replacements by apatite that record sub-micrometer structural details that otherwise would be lost during diagenetic recrystallization. We herein discuss the methodology by which one can infer original shell microstructure from phosphatized fossils, pointing out the main problems and solutions in interpreting these traces of original shell crystal morphology. We also review the information these fossils have provided about the earliest evolution of the mollusc shell. Our long-term goal is to create a dataset of microstructures in early molluscs, which will be useful in understanding the incipient evolutionary arms race between molluscs and their predators, and will help elucidate how the mollusc biomineralization toolkit was built through time.

There is limited documentation on the status and dynamics of fished marine shelled mollusc species in many countries. Some of the challenges are due to obscure documentation of species, extensive unregulated and unrecorded fishing and unawareness of drivers behind declining stocks. The lack of understanding makes it difficult to formulate effective management plans. Here, we assess the fishers’ perceptions on changes in abundance of targeted marine shelled mollusc species and status of associated fished habitats. We interviewed 132 marine shelled mollusc gleaners (fishing by walking) at five sites in coastal Kenya. We established that a multispecies marine shelled mollusc fishery is present in Kenya and that this fishery is conducted by both women and men. We distinguished 158 different shelled mollusc species being targeted. The gleaners perceived a temporal decline of gleaned species. The main causes for the decline were perceived to be overfishing of shells, elevated sea-surface temperature and habitat destruction. The more experienced gleaners perceived a greater decline indicating a baseline shift in perceptions. Our findings suggest that local ecological knowledge is useful to understand historic changes in fisheries lacking long-term scientific data. Furthermore, it highlights the potential benefits of a collaboration between ecologists and gleaners to improve our understanding of the status and dynamics of fishing of marine shelled molluscs as well as other types of fishing.

Biogenic carbonate mollusc shells have the unique property of being a durable material found in many archaeological and geological sites, recording in their shell chemical composition the ambient environmental conditions during the mollusc's lifespan. In particular, mollusc shell Mg/Ca ratios have been suggested to be related to seawater temperature, although such a relationship is controversial and appears to be species- and even location-specific. This study investigates the use of Laser-Induced Breakdown Spectroscopy (LIBS) for the rapid measurement of Mg/Ca profiles within Patella vulgata shells, via comparison with one established analytical technique that is most often used for this purpose, ICP-OES. LIBS offers some advantages over other spectrometric techniques, including ICP-OES, the latter requiring initial micromilling of sample powders. LIBS offers faster measurement, reduced sample preparation, easier automation and less complex and lower cost instrumentation. A high correlation is evident between LIBS and ICP-OES Mg/Ca profiles within four archaeological P. vulgata shells, as well as strong similarities between LIBS measurements made in two different areas of each P. vulgata shell (i.e. the apex and a more conventional transect along the axis of shell growth). Validation of the LIBS technique for determination of Mg/Ca profiles within P. vulgata shells has implications for archaeological studies, because a greater number of shell specimens sampled from each archaeological site and chronological level can be measured, thereby improving the statistical robustness of data interpretation and conclusions. One example archaeological application that would benefit from application of the LIBS technique is identification of the season-of-capture of marine molluscs as a food resource for prehistoric societies. This research was performed as part of the projects “TRACECHANGE: Tracing Climatic Abrupt Change Events and its Social Impact during the Late Pleistocene and Early Holocene (15-7 ky cal BP) (HAR2013-46802-P)”, and “Photonics Sensors for Safety & Security (SENSA)” (TEC2016-76021-C2-2-R), both funded by the Spanish Ministry of Economy and Competitiveness. A. García-Escárzaga’s work was funded by the University of Cantabria through a predoctoral grant and I. Gutiérrez-Zugasti’s work was funded by the Spanish Ministry of Economy and Competitiveness through a Juan de la Cierva grant (grant JCI-2012-12094).

Nacre is the inner layer of the mollusc shell and provides exceptional toughness via its highly organized organic–inorganic composite structure. Pif is an organic matrix protein from the nacreous layer of the pearl oyster Pinctada fucata and exhibits regulatory behavior in nacre formation. Here, we investigated features of Pif97, the N-terminal of Pif, using a recombinant form of Pif97 produced in Escherichia coli. We observed that recombinant Pif97 was able to efficiently form a complex with calcium ions. Additionally, recombinant Pif97 showed both in vitro growth inhibition of thermodynamically stable calcite, stabilization of amorphous calcium carbonate, and exclusive binding affinity to metastable aragonite and chitin. These results imply the participation of Pif97 in the calcification of nacre including the association of the inorganic phase and polysaccharide template. We propose that recombinant Pif97 has inherent characteristics of the native form, which are significant for interrelating with orga...

Calcareous root tubes are widely distributed across the Badain Jaran Desert and the Tengger Desert of the Alashan Plateau in northwest China. However, the reliability of their 14 C dating results and their environmental significance remain unclear. In this study, the conventional 14 C ages of 31 calcareous root tube samples and one aquatic mollusc shell sample, which were all collected from the Badain Jaran Desert and the Tengger Desert, were measured. The results reveal that nine of the 14 calcareous root tube samples from the Badain Jaran Desert were from Marine Isotope Stage (MIS) 3, while two samples were from MIS 2. The other three samples were dated to the mid-Holocene, one of which is consistent with the aquatic mollusc shell sample collected from the shoreline of Zhunzhahanjilin Lake in the Badain Jaran Desert. Moreover, the 17 calcareous root tube samples from the Tengger Desert were all dated to the mid- and late-Holocene, most of which were from the mid-Holocene. The results demonstrate that calcareous root tubes can be used as

Bio-derived honeycomb-like ordered macroporous carbon with highly interconnected hexangular channels and excellent electronic conductivity is prepared by carbonizing the organic matrix of mollusc shells. The unique structure ensures fast electron transfer throughout the entire three-dimensional network and effective electrolyte penetration, which makes the mollusc shell derived carbon network (MSDCN) an ideal substrate for supercapacitor electrodes. Via a simple hydrothermal process, cubic Co3O4 was incorporated with the MSDCN, and the as-obtained Co3O4@MSDCN exhibits an outstanding electrochemical performance with high specific capacitance (1307 F g−1 at 1 A g−1), impressive rate performance (with a capacity retention of 61.0% at 20 A g−1) and long cycle life (84% of the initial capacitance remained after 3000 cycles at 5 A g−1).

Marsh clams (Polymesoda sp.) were an important dietary item for pre-Columbian people living along the Caribbean coast of Nicaragua. Their intensive exploitation is synchronous with major cultural changes associated with the emergence of socio-political complexity in Central America. In this paper we present the results of an oxygen isotope seasonality study on archaeological shells retrieved from Karoline, a shell midden site dated to ~2 cal kBP and located along the southern margin of Pearl Lagoon (Caribbean coast of Nicaragua). Modern shells ( Polymesoda arctata) were also analysed for stable isotopes. The results indicate that archaeological specimens from Karoline may have experienced different hydrological conditions or nutrient supply within the lagoon compared to present day. The seasonal analysis reveals that there were no preferential seasons for the collection of marsh clams during the distinct phases of site formation; instead, exploitation occurred throughout the year.

Molluscs possess a number of attributes that make them an excellent source of past environmental conditions in estuaries: they are common in estuarine environments; they typically have hard shells and are usually well preserved in sediments; they are relatively easy to detect in the environment; they have limited mobility as adults; they grow by incremental addition of layers to their shells; and they are found in all the major environments surrounding estuaries—terrestrial, freshwater, brackish, and marine waters. Analysis of molluscan assemblages can contribute information about past changes in sea level, climate, land use patterns, anthropogenic alterations, salinity, and other parameters of the benthic habitat and water chemistry within the estuary. High-resolution (from less than a day to annual) records of changes in environmental parameters can be obtained by analyzing the incremental growth layers in mollusc shells (sclerochronology). The shell layers retain information on changes in water temperature, salinity, seasonality, climate, river discharge, productivity, pollution and human activity. Isotopic analyses of mollusc shell growth layers can be problematic in estuaries where water temperatures and isotopic ratios can vary simultaneously; however, methods are being developed to overcome these problems. In addition to sclerochronology, molluscs are important to Holocene and Pleistocene estuarine palaeoenvironmental studies because of their use in the development of age models through radiocarbon dating, amino acid racemization, uranium-thorium series dating, and electron spin resonance (ESR) dating.

We report a temperature calibration for Δ 47 from bivalve carbonate that lies within error of theoretical predictions (Schauble et al., 2006; Guo et al., 2009). The temperature sensitivity of this calibration is lower than several different earlier calibrations determined using either inorganic calcite, corals, foraminiferans and coccoliths, or brachiopods and bivalved molluscs, but it agrees with more recent Δ 47 -temperature relationships determined from measurements of clumped-isotopes in mollusc and brachiopod shells. We demonstrate that mollusc shell temperature calibrations originating from different laboratories that have not been corrected for instrument backgrounds may differ by as much as ∼0.07‰ in Δ 47 over the ∼0 to 30 °C temperature range even where dΔ 47 /d T agree. Because recent calibrations for Δ 47 vs. T from several different laboratories agree for bivalved mollusc shells, yet differ from an early calibration for bivalved molluscs, we suggest it is unlikely that temperature-Δ 47 variability is attributable to phylum-specific vital effects, and instead conclude that differences in calibration slope between phyla and/or inorganic calcite are more easily explained by variability in measurements made in different laboratories. Discrepancies in both calibration slopes and/or intercepts indicate that Δ 47 values measured in natural materials may be more significantly influenced by instrument-specific effects, as well as effects from sample preparation and handling and purification of CO 2 than current techniques are able to correct for, and therefore, temperatures obtained by comparing measurements of Δ 47 to independently determined calcite calibrations may err by a far greater amount than acknowledged in previous studies.

Mollusc shells introduce complexity and heterogeneity into soft-sediment habitats and might regulate the structure and functioning of benthic assemblages. Two areas of an unvegetated tidal flat located at the mouth of Paranagua Bay (southern Brazil) largely differ in substrata characteristics and macrofaunal assemblage structure. Sediments of the inner part of the studied site are structurally more complex than those of the peripheral portion, due to high densities of empty shells of the bivalve Anomalocardia brasiliana. The effects of this biogenic matrix on macrofaunal recolonisation during a three-month period were assessed through a reciprocal transplantation experiment of defaunated sediment between shelled and bare habitats. Hypotheses were tested to distinguish between three possible causes of variation: (i) habitat complexity, (ii) intrinsic factors of each area (regardless of the presence/absence of shells), and (iii) their interaction. Habitat structural heterogeneity provided by empty shells does not explain the large differences between macrofauna in shelled and bare habitats. Assemblages that colonised transplanted sediments became similar to those in controls at the area to which they were moved, but differed from those in controls at the area where they originated. The lack of a consistent response of assemblages to the presence of shells can be explained not only by the extremely fast recovery following small-scale experimental disturbances, but also by the dispersal mechanisms related to reproductive traits of the dominant taxa. Changes in assemblages were greatly influenced by the tanaid Monokalliapseudes schubarti, the numerically-dominant species that showed consistent differences among treatments. The reduced dispersal capacity due to the lack of planktonic larval stages associated with high fecundity, continuous reproduction and fast growth were determinant features for the rapid colonisation of defaunated sediments, regardless of habitat complexity. Despite the well-recognised impact of mollusc shell production on soft-sediment habitats, our study showed that its effects are scale-dependent, both spatially and temporally, and might be regulated by the structure of local assemblages and species-specific responses related to dispersal mechanisms.

Mollusc shell biomineralisation involves a variety of organic macromolecules (matrix proteins and enzymes) that control calcium carbonate (CaCO3) deposition, growth of crystals, the selection of polymorph, and the microstructure of the shell. Since the mantle and the hemocytes play an important role in the control of shell formation, primary cell cultures have been developed to study the expression of three biomineralisation genes recently identified in the abalone Haliotis tuberculata: a matrix protein, Lustrin A, and two carbonic anhydrase enzymes. Mantle cells and hemocytes were successfully maintained in primary cultures and were evaluated for their viability and proliferation over time using a semi-automated assay (XTT). PCR and densitometric analysis were used to semi-quantify the gene expression and compare the level of expression in native tissues and cultured cells. The results demonstrated that the three genes of interest were being expressed in abalone tissues, with expression highest in the mantle and much lower in the hemocytes and the gills. Biomineralisation genes were also expressed significantly in mantle cells, confirming that primary cultures of target tissues are suitable models for in vitro investigation of matrix protein secretion.

Covering behavior is a common but strange behavior in the sea urchin Glyptocidaris crenularis.The evolutionary basis of the behavior remains largely unknown and unclear.We investigated the effects of different ecological environments in the laboratory on the characteristics of the covering behavior of the sea urchin G.crenularis.We used three different environments: with shells(covering group),with brick(sheltering group) and without covering materials(blank group).After seven months culture in each environment,we observed the covering behavior of the sea urchin G.crenularis using shells of two species of bivalve molluscs(Ruditapes philippinarum and Mytilus edulis) as potential covering material.The results showed that sea urchins in covering and sheltering groups picked up a shell and placed it onto its upper surface in a significantly shorter time than those in the blank group(P0.05).The number of sea urchins displaying covering behavior and the number of shells used for covering over time increased to a plateau for all three groups.The number of sea urchins displaying covering behavior reached the plateau at 40,40 and 160 minute in the covering,blank and sheltering groups,respectively.The number of shells used for covering in covering,blank and sheltering groups reached plateau at 40,40 and 120 minutes,respectively.Significantly more sea urchins displayed the covering behavior in the sheltering group than the other two groups(P0.05).However,there was no significant difference between the other two groups(P0.05).The number of shells used for covering was similar for the three groups(P0.05).However,the species of mollusk shell sea urchins used to cover differed significantly(P0.05).The percentage of sea urchins that used only one mollusc shell species as the covering material reached 78%.Long exposure to light could influence the covering behavior of G.crenularis.The degree of covering behavior decreased in sea urchins that were exposed to light for a period of time.Light may be a selective pressure for the covering behavior.The covering behavior may be the result of a long-term evolutionary process because all sea urchins maintained the covering behavior in the different environments.Glyptocidaris crenularis could not loss the covering behavior due to the lack of covering material in a period of time,although the intensity and degree of the covering behavior could be influenced.Glyptocidaris crenularis showed obvious selectivity to the type of covering material.This may be related to the characteristics of the covering material and the physiological state of the sea urchins.We think that the covering behavior is possibly one of the strategies to avoid light.Other strategies to avoid light could be selected by G.crenularis if habitats in the field lack covering and sheltering materials.The covering behavior of G.crenularis can be influenced by various factors.The comprehensive effects of these factors on covering behavior and the effect of covering behavior on physiology in G.crenularis needs further study.

Curious eroded depressions, most resembling an eye shedding an elongate tear, are found in gently sloping, intertidal, carbonate-rich arenite outcropping on the sea coast near Lakes Entrance, Victoria, southeast Australia. The depressions, known locally as "Tears of the Virgin," are evidently formed by multiple generations of a barnacle, Chthamalus antennatus Darwin, 1854 in association with cyanobacteria. While the round part of a depression offers the barnacle a modicum of protection from impacts during high tides, it is also partially inhabited by cyanobacteria, which extend into and tend to fill the elongate tear. As such, this appears to be the first case of mutualism between a higher invertebrate and cyanobacteria, with the cyanobacteria reducing the barnacle's risk of desiccation while receiving metabolic wastes from it during low tides. It is also the first record of a balanomorph barnacle eroding calcareous arenite beneath its shell, the net effect of which would be expected to reduce its adhesion to the substrate. However, the siliceous residue, resulting from the barnacle's dissolution of the more than 80% of the calcite-rich sedimentary rock, is sequestered in delicate folds on the inside of the shell wall as it grows. A brief review of cirripedes capable of excavation includes the first photographic documentation of excavation of a mollusc shell by a verrucomorph.

The Anadaragranosa and Pernaviridis shell sample were prepared in powder and plate form has been studied. The crystal structure of the shells was studied by x-ray diffraction (XRD). The identification and quantitative analysis were performed by the XRD patterns and the Rietveld method. It found that the crystal structure of Anadaragranosa shells is a pure aragonite phase, and the Pernaviridis shells is a mixture phase of aragonite and calcite. Also we used the scanning electron microscope (SEM) to study the Morphology of the Anadaragranosa and Pernaviridis shell sample. The results on SEM micrographs agree well with those of XRD. The results from SEM can be described the textural information and used to determine of the mollusc shell. In addition, the metals in the shells were determined by ESR spectroscopy. The metals in all samples reveals that Mn were found in all mussel shells, and then the ESR spectrum agree well with those of XRD and SEM result, then it can be used to indentification of structural of mollusc shell.

Synthesis hydroxyapatite (HA) powders from mollusc shell with the solid solution reaction method. The process is a new method which makes the amount of HA powder in large quantities. The advantage of the solid state method which involves molar ratio of calcium and phosphorus through a thermal treatment and reaction time, caused by the diffusion of ions in the solid particles. HA is the only apatite present in the reaction products, apart from minute fractions of certain other calcium compounds. The final product is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared (FTIR)

The mollusk shell mobilizes calcium from environment for skeletal mineralization. This occurs through synthesizing solids in solution in the presence of organic molecules of specific interior regions of the conch shell. The ultrastructure and microhardness of the Hemifusus tuba conch shell living in the Huang/Bo sea area are investigated in the paper. It is shown that the composition and microstructure of the mollusk shell vary in different positions. The prodissoconch shell consists only of aragonite with the crossed-lamellar microstructure. While the spiral shell and the body shell of the Hemifusus tuba conch shell are composed of one calcite layer and several aragonite layers. The calcite layer consists of cylindrical grains, but the aragonite layers are crossed-lamellar ultrastructure at three size scales. The minimum structure size (the third-order lamella) is at about 20 nm − 80 nm. The margin of shell aperture is only composed of calcite with cylindrical grains. This natural optimization of the shell microstructure is intimately due to the growth of the organic matrix. At different positions the microhardness of mollusc shell is different due to different crystal structures and crystal arrangements. The growth process of shells allows a constant renewal of the material, thus enabling their functional adaptation to external environments.

Strong textures of mollusc shell layers are utilised to provide phylogenetic information. Aragonitic and calcitic layers are the targets here, inside which nacre layers, but not only, play a specific role. At the light of the texture patterns and a parcimonious approach, nacre appears not as an ancestral form of calcium carbonate in mollusc layers. Also, from texture terms we can propose some links to ancestral fossilised species. The aragonite unit-cell distortions due to macromolecule complex insertions in the microstructures are measured on raw specimens for several aragonite layers of gastropods and bivalves. The textural information is used to provide precise structural determination of the biogenic aragonite. Such information might provide useful lights on the biomineralisation processes in the future, in cladistic approaches. Farming conditions are shown not to influence much shell textures of Helix aspersa aspersa. Closely related species exhibit globally close textures, among which three are good candidates for bone neogeneration and which textures are identical. Electrodeposition of aragonite, with inclusion of molecular extract from shell species, results in nacre-like layers exhibiting structural distortions similar to known inductive layers. X-ray diffraction experiments are shown to provide invaluable insights in testing biomineralisation and phylogenetic hypotheses.

Kim, J.K., Khim, B.-K., Woo, K.S., & Yoon, S.H. 2009: Records of palaeo-seawater condition from oxygen-isotope profiles of early Pleistocene fossil molluscs from the Seoguipo Formation (Korea). Lethaia, Vol. 43, pp. 170–181. High-resolution δ18O profiles of early Pleistocene fossil molluscs (Mizuhopecten tokyoensis hokurikuensis) from the shallow-marine sedimentary Seoguipo Formation (Korea) were found to exhibit distinct annual cycles identified by their unique seasonality (δ18O amplitude). A direct comparison of fossil δ18O profiles with that of living shells (Amusium japonicum japonicumi) indicated that the palaeoseawater conditions differed from present-day seawater. Specifically, the positive δ18O shift in the isotope profile of the fossil specimens relative to that of the living mollusc shell reflected that palaeotemperature was lower than that today. However, a comparison of the coldest palaeotemperatures (determined from the heaviest δ18O values of fossil shells), with the present-day winter temperatures indicates that temperature variation alone cannot account for the entire positive δ18O offset. These findings indicate that variation in the seawater δ18Ow values plays a dominant role in the biogenic carbonate precipitation of fossils. Thus, the fossil shells obtained from stratigraphic units suggest different palaeoenvironmental conditions, including lower temperatures and 18O-enriched glacial seawater, when compared with the present-day conditions. The Seoguipo Formation records at least five cycles of relative sea-level fluctuations, with changes in fossil δ18O amplitudes separated by sequence boundaries likely to reflect variations of unique palaeoseawater condition, although the oxygen-isotope profile of fossil molluscs appears to provide a snap-shot of the palaeoclimatic signature. □Early Pleistocene, mollusc fossils, oxygen isotope, palaeoenvironment, seawater temperature.

The pottery investigated in this study comes from late mesolithic inland sites next to rivers in Northern Germany. The first AMS 14C datings of food crusts from these sites showed surprisingly high ages, which could be caused by the hardwater effect. Modern samples from the rivers have ages of several hundred 14C years, and a modern food crust prepared from fish with a certain reservoir age shows the same age as the fish. Surprisingly, there was a large age difference between water samples and fish/mollusc shell from the same river. Associated archaeological samples of terrestrial and fluvial origin show age differences of several hundred and up to 3000 years. These high age differences are only to a limited extent transferred to the archaeological food crusts.