Shell Patterns Research Articles

Interior shell patterns among the Spondylid species (Bivalvia: Spondylidae) in Mindanao, Philippines

Abstract. Ruaza FJC, Maturan DC, Bustillo E. 2024. Interior shell patterns among the Spondylid species (Bivalvia: Spondylidae) in Mindanao, Philippines. Biodiversitas 25: 2901-2906. The variations among the species of the Spondylus were assessed based on its interior shell pattern using landmark-based geometric morphometry. A total of 200 specimens were subjected to analysis. Samples of the Spondylid species were collected and photographed, and 15 landmarks from internal shell morphology were quantified and analyzed. The landmarks include the umbo, teeth, size of the muscle scar, and the pallial sinus. Multivariate analysis of variance revealed significant differences in internal shell characters among Spondylid species across sampling sites (p<0.05). Canonical Variance Analysis (CVA) effectively differentiated the local Spondylid species into distinct clusters. In addition, the relative warps captured the most significant sources of variation in the morphological characters analyzed, leading to effective differentiation between the groups or populations of the species. The most distinguishing characteristics among the species are the distance of the pallial line to the ventral tip of the adductor muscle scar and the size of the cardinal tooth. The internal shell characters among the Spondylid species exhibit notable disparity despite their great morphological similarity. These shell characters can be used in the identification while conservation efforts are still in the initial stage of development. The presence of notable dissimilarities in the internal shell characteristics among the Spondylid species indicates that even slight deviations can result in noticeable morphological distinctions. This discovery enhances the understanding of the species divergence within this group and underscores the significance of incorporating internal shell characteristics into taxonomic and ecological investigations.

Vibrations of skew cylindrical shells made of FG-GPLRCs under rapid surface heating

An analysis is performed in this research to examine the thermally induced vibrations in skew cylindrical shells. It is assumed that shell is made from a composite laminated material where each layer is reinforced with graphene platelets (GPLs). The amount of GPLs in the layers may be different which results in a piecewise functionally graded media. The one-dimensional transient heat conduction equation is established through the thickness of the shell. Heat conduction equation is solved using the finite difference method for each layer and continuity of temperature and heat flux is applied between the layers. Crank Nicolson algorithm is implemented to obtain the temperature profile at each time step and after that thermally induced force and moment are evaluated. The kinematics of the shell are estimated following the first order shear deformation shell theory. Also it should be noted that an oblique coordinates system in addition to orthogonal system is defined which make it easier to apply the boundary conditions. The definition of strain and kinetic energies are constructed and Following the Ritz method whose shape functions are estimated by Chebyshev polynomials, energies are provided in discrete form of the governing equations. Results of this study are provided to explore the effects of thermal and mechanical boundary conditions, geometry of the shell, weight fraction and distribution patterns of GPLs. It is highlighted that thermally induced vibrations indeed exist especially in thin class of shells.

Trace Element Patterns in Shells of Mussels (Bivalvia) Allow to Distinguish between Fresh- and Brackish-Water Coastal Environments of the Subarctic and Boreal Zone

The accumulation of trace metals in the shells of bivalves allows quantitative assessments of environmental pollution and helps to reconstruct paleo aquatic environments. However, the understanding on how marine and freshwater mollusks control the level of trace elements in their shells remains very limited. Here, we compared the trace element composition of marine and freshwater bivalves from boreal and subarctic habitats, using examples of widely distributed species of marine (Mytilus edulis, M. trossulus) and freshwater (Anodonta anatina, Unio sp., Beringiana beringiana) mussels. Sizable differences in several trace element concentrations were detected between different species, depending on their environmental niches. A multiparametric statistical treatment of the shell’s elemental composition allowed to distinguish the impact of external factors (water and sediment chemical composition) from active metabolic (biological) control. In particular, the obtained results demonstrated that Ba:Ca and Pb:Ca ratios in mussels’ shells are closely related to the primary productivity of aquatic ecosystems. The Mn:Ca ratio allowed to constrain the environmental conditions of mussels’ species depending on the trophic state of inhabited waterbody. Overall, the marine mussels exhibited stronger biological control of trace element accumulation, whereas trace element pattern in shells of freshwater mussels was chiefly controlled by environmental factors. The obtained results might help to use the trace element composition of bivalves in distinguishing marine and freshwater habitats of mollusks in paleo environments.

DNA barcoding Clithon sp. (Gastropoda: Neritidae) from Badur Beach, Madura, Indonesia, based on COI gene molecular marker

Abstract. Djoemharsjah IS, Ambarwati R, Rahayu DA. 2023. DNA barcoding Clithonsp. (Gastropoda: Neritidae) from Badur Beach, Madura, Indonesia, based on COI gene molecular marker. Biodiversitas 24: xxxx. Neritidae is polymorphic with various shell colors and patterns; therefore, they were doubts about the identifying species from the genus Clithon, namely Clithon sp. from Badur Beach of Madura Island, Sumenep District, East Java Province, Indonesia. In addition, DNA barcoding could provide genetic information using short DNA sequences to quickly and precisely identify species. This study aimed to identify the genus Clithon sp. from Badur Beach, based on Cytochrome Oxidase subunit I(COI) genes and analysis of phylogenetic relationships. The research methods include sampling, sample preservation, morphological identification of species, DNA isolation, amplification, electrophoresis, and sequencing using the Sanger method with genetic analysis using bioinformatics software. The results of COI barcode identification obtained a DNA sequence length of 490bp with a similarity value of the three Clithon sp. samples between 96.75 to 98.97%. The identification with the Barcode of Life Data System consisted of three variations of nucleotide bases, and the average value of the genetic distance with the in-group was 1.74% as Clithon sp. The Phylogenetic tree Clithon sp. from Badur Beach, was in the same clade as Clithon sowerbianum Récluz 1843 and Clithon mertonianum Récluz 1843 with the Neighbor-Joining Tree and Maximum Likelihood methods with bootstrap values between 96-100. Therefore, the COI barcode DNA markers analysis successfully identified Clithon sp. from Badur Beach, Madura, Indonesia as C. sowerbianum.

Secretory and transcriptomic responses of mantle cells to low pH in the Pacific oyster (Crassostrea gigas)

Since the Industrial Revolution, the concentration of atmospheric carbon dioxide (CO2) due to anthropogenic activities has increased at unprecedented rates. One-third of the atmospheric anthropogenic CO2 emissions are dissolved in the oceans affecting the chemical equilibrium of seawater, which in turn leads to a decrease in pH and carbonate ion (CO32-) concentration, a phenomenon known as ocean acidification (OA). This chemical disequilibrium can be detrimental to marine organisms (e.g., mollusks) that fabricate mineralized structures based on calcium carbonate (CaCO3). Most studies on the effect of reduced pH in seawater have been conducted on the early developmental stages of shell-building invertebrates, given less attention to how adult individuals face OA stress. Here, we evaluate histological, secretory, and transcriptional changes in the mantle of adult oysters (Crassostrea gigas) exposure to ambient (8.0 ± 0.2) and reduced (7.6 ± 0.2) pH during 20 days. Most histological observations did not show differences in terms of mantle cell morphology. However, Alcian Blue/PAS staining revealed significant differences in the number of Alcian Blue positive cells in the mantle edge, suggesting a decrease in the secretory activity in this morphogenetic zone. Transcriptomic analysis revealed 172 differentially expressed genes (DEGs) between mantle tissues from adult oysters kept in normal and reduced pH conditions. Almost 18% of the DEGs encode secreted proteins that are likely to be contributing to shell fabrication and patterning. 17 of 31 DEGs encoding secreted proteins correspond to oyster-specific genes, highlighting the fact that molluscan shell formation is underpinned by a rapidly evolving secretome. The GO analysis of DEGs encoding secreted proteins showed that they are involved in the cellular response to stimulus, response to stress, protein binding, and ion binding, suggesting these biological processes and molecular functions are altered by OA. This study demonstrates that histology and gene expression profiling can advance our understanding of the cellular and molecular mechanisms underlying adult oyster tolerance to low pH conditions.

Hydrological controls on base metal precipitation and zoning at the porphyry-epithermal transition constrained by numerical modeling

Ore precipitation in porphyry copper systems is generally characterized by metal zoning (Cu–Mo to Zn–Pb–Ag), which is suggested to be variably related to solubility decreases during fluid cooling, fluid-rock interactions, partitioning during fluid phase separation and mixing with external fluids. Here, we present new advances of a numerical process model by considering published constraints on the temperature- and salinity-dependent solubility of Cu, Pb and Zn in the ore fluid. We quantitatively investigate the roles of vapor-brine separation, halite saturation, initial metal contents, fluid mixing and remobilization as first-order controls of the physical hydrology on ore formation. The results show that the magmatic vapor and brine phases ascend with different residence times but as miscible fluid mixtures, with salinity increases generating metal-undersaturated bulk fluids. The release rates of magmatic fluids affect the location of the thermohaline fronts, leading to contrasting mechanisms for ore precipitation: higher rates result in halite saturation without significant metal zoning, lower rates produce zoned ore shells due to mixing with meteoric water. Varying metal contents can affect the order of the final metal precipitation sequence. Redissolution of precipitated metals results in zoned ore shell patterns in more peripheral locations and also decouples halite saturation from ore precipitation.

Numerical simulation on hydrodynamic lubrication performance of bionic multi-scale composite textures inspired by surface patterns of subcrenata and clam shells

Inspired by the surface of shells in natural world, six bionic multi-scale composite surface textures were designed. Numerical simulation was carried out to investigate the mechanism for influences of the texture geometric parameters and service conditions on lubrication characteristics. The results revealed that the bionic surface enhanced the load-carrying capacity and reduced the friction coefficient. Groove combinations offered a better lubrication performance than wavy combinations. The texture geometric parameters showed significant influence on the frictional characteristics. For all texture shapes, the load-carrying capacity increased approximately linearly with the rotational speed and decreased with the water film thickness. The results would help guide effective texture design to improve the lubrication performance of axial piston pump friction pairs under marine environments.

First principles insights into the relative stability, electronic and catalytic properties of core-shell, Janus and mixed structural patterns for bimetallic Pd-X nano-alloys (X = Co, Ni, Cu, Rh, Ag, Ir, Pt, Au).

The three well-known orderings of the two constituting atomic species in a bimetallic nano-alloy - core-shell, Janus and mixed structural patterns - may be interconvertible depending on the synthesis conditions. Using first principles electronic structure calculations in the present work, we look for the microscopic origin for such structural transformation considering eight Pd-related bimetallic nano-alloys. Our analysis shows that it is the change in atom-atom covalency that is responsible for such structural transformation. Our study also reveals that the three patterns are distinctly identified in terms of total orbital hybridization. Finally, we have analyzed the trend in the relative catalytic activity for the three structures of each bimetallic nano-alloy using the d-band model. Our analysis indicates that the trend in the catalytic activity for the bimetallic Pd-X nano-alloys seems to be intermediate to those of the pristine Pd and Pt nano-clusters possessing similar structure and equal number of total atoms. Among the studied binary nano-alloys, the bimetallic Pd-Ni nano-alloy appears as the most suitable binary pair to develop a non-Pt catalyst.

Population effects of chiral snail shell development relate handedness to health and disease

The spiral patterns of snail shells exhibit chirality, or “handedness.” These patterns often heavily favor the dextral (right-handed, or clockwise) over the sinistral (left-handed, clockwise) phenotype. While the developmental pathways resulting in each enantiomorph (non-superimposable mirror image form) have been studied extensively, there has been limited investigation into how the emphasis on one spiral direction over the other may confer survival benefit. This perspective essay proposes that developmental events determining cell cleavage robustness, mating compatibility, and predator evasion can influence the distribution of dextral and sinistral snails. The connection between chirality and survivability has broader implications for exploring the role of handedness in diseases and their treatments.

Gastropods Colour Patterns in Cassiopids and Naticids from Romualdo Formation, Araripe Basin, Northeast Brazil

The phylum Mollusca includes one of the most beautiful examples of colour patterns in present-day shells. However, they are rare in the fossil record because they demand excellent fossilization. In Brazil, colour patterns in fossil mollusk shells are recorded in gastropods Natica aff. bulbulus White, 1887 from the Riachuelo Formation (Aptian-Albian), Sergipe-Alagoas Basin. This paper presents the first gastropod shells from the Romualdo Formation with colour patterns, visible under natural and UV light, belonging to the families Naticidae and Cassiopidae, collected at Santo Antônio outcrop municipality of Exu, Pernambuco and, Pinheiro and Serra do Mãozinha sites, municipality of Missão Velha and Romualdo site, municipality of Crato, Ceará. Among the cassiopids more than 100 specimens were tested, with 1/3 of them showing a residual colour pattern under UV light exposure, after chemical preparation. They correspond to the species Paraglauconia (Diglauconia) araripensis (Beurlen, 1964), Paraglauconia (Diglauconia) lyrica Maury, 1934, Gymnentome (Gymnentome) carregozica (Maury, 1934) and Gymnentome (Gymnentome) romualdoi Beurlen, 1964. The colour pattern is virtually similar in both genera, with fluorescent stripes on a dark background, showing the taxonomic similarity between them. As for the naticids, about 20 specimens were collected and 15 show good preservation, observing the visible colour pattern under natural light in Natica sp. and Euspira sp.; both new taxa for the Araripe Basin. The residual colour pattern in naticids ranges from spiral stripes to sigmoidal lines and blotches of brown and yellowish tones on a paler background, as observed in fossil species of the same family in the Cenozoic. The new occurrences increase the fossiliferous diversity of mollusks of the Romualdo Formation and extend the understanding of the diversity of colouration patterns of Lower Cretaceous gastropods.

Morphology and Genetic Structure Profile of Farmed Snails Cornu aspersum aspersum and Cornu aspersum maximum in Greece

The subspecies of the species Cornu aspersum, C. a. aspersum, and C. a. maximum are the dominant farmed species in Greece. The morphological and molecular polymorphism of the two aforementioned subspecies has not been studied in depth. In this study, the polymorphism of snails of the two subspecies derived from seven snail farms throughout Greece was studied using morphological and molecular markers. Firstly, the snail samples of both subspecies were categorized in three shell patterns based on shell color and existence of bands. The conducted population structure analysis revealed three major clusters among the farmed snail populations. As concerns genetic diversity, six loci (Ha5, Ha6, Ha8, Ha9, Ha10, and Ha11) were tested for their polymorphism. Genetic variation was reported within populations rather than among populations. Finally, the obtained data highlighted a common gene pool broodstock for snail farms throughout Greece.

Evolutionary loss of shell pigmentation, pattern, and eye structure in deep-sea snails in the dysphotic zone.

Adaptations to habitats lacking light, such as the reduction or loss of eyes and pigmentation, have fascinated biologists for centuries, yet have rarely been studied in the deep sea, the earth's oldest and largest light-limited habitat. Here, we investigate the evolutionary loss of shell pigmentation, pattern, and eye structure across a family of deep-sea gastropods (Solariellidae). We show that within our phylogenetic framework, loss of these traits evolves without reversal, at different rates (faster for shell traits than eye structure), and over different depth ranges. Using a Bayesian approach, we find support for correlated evolution of trait loss with increasing depth within the dysphotic region. A transition to trait loss occurs for pattern and eye structure at 400-500m and for pigmentation at 600-700m. We also show that one of the sighted, shallow-water species, Ilanga navakaensis, which may represent the "best-case" scenario for vision for the family, likely has poor spatial acuity and contrast sensitivity. We therefore propose that pigmentation and pattern are not used for intraspecific communication but are important for camouflage from visual predators, and that the low-resolution vision of solariellids is likely to require high light intensity for basic visual tasks, such as detecting predators.

Quantifying shell patterning helps identify species of Trionychidae.

Softshell turtles (Trionychidae) display characteristic pits and ridges, or "sculpturing," on the bony carapace. Variation in sculpturing pattern may be useful in classifying fossilized shell fragments. Although past attempts could discern qualitative differences in certain best-case scenarios, many early taxonomic uses of sculpturing traits have been reevaluated as unreliable in the face of intraspecific variation. The potential of sculpturing to contain consistently reliable, quantitative, taxonomically informative traits remains underexplored. Here, we revisit this idea by quantifying trionychid shell patterning with topographic measurement techniques more commonly applied to nonhomologous quantification of mammalian teeth and geographic surface topography. We assess potential sources of variation and accuracy of these metrics for species identification. Carapaces of extant specimens used in this study included members of the species Apalone ferox, Apalone spinifera, and Amyda cartilaginea and were obtained from the herpetology collections of the Florida Museum of Natural History. 3D scans of shells were systematically sampled to create digital "fragments." These fragments were quantified using three topographic measurements: Dirichlet Normal Energy (DNE), Relief Index (RFI), and Orientation Patch Count Rotated (OPCR). A nested MANOVA suggests there is significant variation at the species, individual, and carapace location levels of analysis. Linear discriminant analysis correctly predicts a sample's species identity from DNE, RFI, and OPCR 75.2% of the time. These promising results indicate that topographic measures may provide a method for identifying shell fragments that are currently identifiable only as Trionychidae indet. Future work should explore this approach in additional species and account for ontogenetic changes.

Middle Devonian microconchids and anticalyptraeids (Tentaculita) from the northern shelf of Gondwana (Morocco): palaeoecological and palaeobiogeographical implications

ABSTRACT Microconchid and anticalyptraeid tubeworms from the Middle Devonian of Morocco are described for the first time. The assemblage, coming from the locality of Madène el Mrakib (Mader Basin, eastern Anti-Atlas), consists of one microconchid species, Palaeoconchus sanctacrucensis, and one new anticalyptraeid species, Anticalyptraea madenensis. Both species encrusted uppermost Eifelian/lowermost Givetian brachiopod shells. P. sanctacrucensis was hitherto only known from the upper Emsian–upper Eifelian of the Holy Cross Mountains, Poland. Thus, its presence in the shelf habitats of northern Gondwana implies its migration from the southern margin of Laurussia during the transgression associated with the late Eifelian Kačák Episode. The encrustation patterns of the brachiopod shells by the Moroccan microconchids indicate that the brachiopods only served as favourable hard substrate for colonisation by the microconchid larvae. However, the occupation of different valves of the same brachiopod by microconchids and Anticalyptraea may imply that both encrusters potentially avoided direct competition for suspended food particles. Characteristics and position of Oichnus borings present on a few microconchids and anticalyptraeids indicate that they were not necessarily formed syn vivo and produced by predatory organisms. It is likely that they were drilled by some tiny suspension-feeders and may represent non-predatory domichnia.urn:lsid:zoobank.org:act:AA095519-5E68-4EDA-B331-E3944F813412

Molluscan Shell Diversity of Ennore Creek, Chennai, India

Molluscs are the soft bodied invertebrates, which are protected by calcium carbonate shells. The shells are coated mostly with calcium carbonate and protein matrix in a process called bio-mineralization. Apart from playing a major role in the aquatic ecosystem, they are considered to be best bio-indicators of environmental pollution, as their soft tissues, and their shells are known to accumulate the pollutants. The divers patterns and different shell morphologies of the clams, snails and oysters, seem to be influenced by the solar radiation, predator stress and various environmental factors, which seem to regulate the gene expression patterns of the shell formation. In the present study, different molluscan shells were collected and studied for their diverse patterns. They were collected from Ennore, creek of Tamil Nadu, India as it is known to be a lagoon type of ecosystem and plays an important role in maintenance of the aquatic ecosystem surrounding it. The present study showed a diverse shell patterns mostly with reference to clam shells. A few, oyster shells, cerithiid shells and potaminind shells were also observed. A detailed analysis of the shell patterns under the influence of various external environmental cues may be investigated in future.

Design of Energy Efficient WSN Using a Noble SMOWA Algorithm

In this paper, the establishment of efficient Wireless Sensor Network (WSN) networks has been projected to minimize the consumption of energy using a new Self-adaptive Multi-Objective Weighted Approach (SMOWA) algorithm for solving a multi-objective problem. The Different WSN nodes deployment policies have been proposed and applied in this paper to design an efficient Wireless Sensor Network to minimize energy consumption. After that, the cluster head for each cluster has been selected with the help of the duty cycle. After configuring the WSN networks, the SMOWA algorithms have been developed to obtain the minimum energy consumption for the networks. Energy minimization, as well as the amount of day-saving, has been calculated for the different WSNs which has been configured through different deployment policies. The major finding of the research paper is to improve the durability of Wireless Sensor Network (i) applying different deployment strategies: (Random, S pattern and nautilus shell pattern), and (ii) using a new Meta-heuristic algorithm (SMOWA Algorithm). In this research, the lifetime of WSN has been increased to a significant level. To choose the best result set from all the obtained results set some constraints such as “equivalent distribution”, “number of repetitions”, “maximum amount energy storage by a node” has been set to an allowable range.

In-Plane Buckling of Open-Section Shell Segments

The present study investigates elastic buckling behavior of open-section shell segments under action of a central radial load. A design parameter is expressed to characterize the influence of fillet radius on load-bearing capacity. A reduction factor equation is developed as a multivariate function of shell parameters, which evaluates the amount of decrease in load-bearing capacity of the structure caused by the corner fillet. In addition, an expression to predict limit load of the shell structure under clamped end conditions is introduced. Furthermore, a parametric study is performed to reveal the influence of fillet radius and radius-to-thickness ratio on the limit load as well as deformation patterns of the open-section shells. Results show that corner fillets has a significant effect on the limit load of the open-section shell segments under in-plane loading.

TINJAUAN TEKNIK PEMBUATAN TAS YANG MENGGUNAKAN MATERIAL BATOK KELAPA

A bag is an object that is often used by all groups, both lower and upper classes. A bag is a tool for carrying an item of luggage Aside from being a place to store an item, a bag is also an important part of the fashion world. Starting from the shape of a bag and the material in the bag that makes bags increasingly become an important part of the fashion world. The types of bags using one of the materials such as coconut shells. Coconut shells are often used as a traditional craft, with natural coconut shell motifs making the patterns look beautiful. This coconut shell material has properties that are quite strong and beautiful in abstract coconut shell patterns. Nowadays, coconut shells are made into a bag material to attract bag users because of their uniqueness.

Significance of abrasion patterns in Recent pectinoid bivalve shells

Significance of abrasion patterns in Recent pectinoid bivalve shells

Novel methods of resolving daily growth patterns in giant clam (Tridacna spp.) shells

Sclerochronology is a powerful tool for high resolution paleoclimate and paleoenvironment reconstruction. However, we can only observe annual growth bands using traditional technology for most marine bivalves, hampering the ability to establish daily resolution chronology in order to reconstruct past weather changes. Giant clams (Tridacna spp.) are the largest bivalves in the world. Their hard and dense aragonite shells have clear annual and even daily growth bands, creating the potential for daily resolution chronology establishment and paleoweather reconstruction. In this study, we present two new and reliable methods that resolve daily growth patterns in giant clam shells: (1) Fluorescence image method. Measuring the width between two bright fluorescent bands of the Tridacna shell with the help of CooRecorder 9.0 software based on the clear daily growth bands obtained by laser scanning confocal microscope (LSCM). (2) Ultrahigh resolution Sr/Ca method. Counting the amount of Sr/Ca ratio data in each daily cycle derived from Tridacna shell, and then calculating the daily growth increment based on the spatial resolution of Sr/Ca data. The results show the variation of daily growth increments profiles obtained by the two methods synchronize, and the chronology uncertainty is statistically acceptable over a long-term record, indicating that both methods can estimate the daily growth increment of Tridacna shell reliably. The methods developed here lay the foundation for paleoweather reconstruction using daily growth increments of Tridacna spp.