{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:62558"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:62558","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Crystallographic texture of the arthropod cuticle using synchrotron wide angle X-ray diffraction","abstract":"Arthropods, which include the crustaceans (e.g. crabs, lobsters, isopods), insects, arachnids (e.g. spiders, scorpions, ticks, mites), and several lesser groups, account for approximately 80 percent of all known animal species. The outer covering of these animals is referred to as exoskeleton or cuticle, and it covers the entire body of the animal. It has remarkable mechanical properties which provide structural support to the body, armor against loads that are externally imposed by predators. It also enables mobility through the formation of joints and attachment sites for muscles. Crustacean cuticle contains alpha-chitin-protein organic fibers associated with crystallites of calcite and considerable amounts of amorphous calcium carbonate (ACC). However, the cuticle of the horseshoe crab Limulus polyphemus contains mainly alpha-chitin-protein fibers, but no crystalline biominerals. In this study, X-ray pole figure analysis was performed to investigate the preferred orientation (crystallographic texture) of calcite and alpha-chitin, in the crustaceans, edible crab Cancer pagurus and american lobster Homarus americanus cuticles, with respect to their orientation relationship firstly, and their alignment with respect to the cuticle geometry secondly. The preferred orientation of alpha-chitin in the cuticle of horseshoe crab was also determined. Synchrotron wide-angle X-ray diffraction (XRD) was employed in studying the texture of samples from different parts of the exoskeleton. The importance of the crystallographic textures in biological materials lies in its direct relationship with its possible role of the contained macromolecules in controlling the epitaxy of the minerals during the biomineralization process. Furthermore, it reveals information about the topological texture, which is represented by the fibers' arrangements in the cuticle. This study shows that crab and lobster cuticles reveal a strong crystallographic texture and preferred orientation correlation between the orientation distribution of calcite and alpha-chitin. It was observed that the c-axis of the hexagonal calcite and the b-axis of the orthorhombic alpha-chitin are firstly preferentially aligned parallel to each other and secondly oriented along the surface normal, whereas the other axes are co-aligned with respect to each other throughout the cuticle plane. The observed spatial rotational freedom of the c-axis of alpha-chitin (fiber axis) represents the twisted plywood structure of the alpha-chitin fibers as observed in scanning electron microscopy (SEM). Additionally, a smaller fraction of the alpha-chitin unit cells in lobster and crab cuticle is oriented with their fiber axis toward the cuticle surface, which was also observed in the SEM images of the cuticle. The texture of the horseshoe crab contains two strong fiber texture components perpendicular to each other. The first one is characterized by a very strong crystallographic orientation of b-axis parallel to the surface normal, whereas the other axes are co-aligned through the cuticle surface plan, which is similar to the observed strong fiber texture component in crustacean cuticle. The second fiber texture component is characterized by a strong crystallographic orientation of c-axis (alpha-chitin fiber direction) with a preferred alignment pointing parallel to the cuticle plane. The synchrotron X-ray crystallographic texture results gave for the first time a statistical description of the orientation relationship between the organic and inorganic components in arthropod cuticle, consistent with the morphological texture determined by SEM. This result strongly suggests that the fibrous structure of alpha-chitin assists the growth of calcite crystals in crustacean cuticle by functioning directly or indirectly as a template for nucleation and subsequent growth of calcite on the basis of oriented nucleation and epitaxial growth of calcite.","abstract_html":"Arthropods, which include the crustaceans (e.g. crabs, lobsters, isopods), insects, arachnids (e.g. spiders, scorpions, ticks, mites), and several lesser groups, account for approximately 80 percent of all known animal species. The outer covering of these animals is referred to as exoskeleton or cuticle, and it covers the entire body of the animal. It has remarkable mechanical properties which provide structural support to the body, armor against loads that are externally imposed by predators. It also enables mobility through the formation of joints and attachment sites for muscles. Crustacean cuticle contains alpha-chitin-protein organic fibers associated with crystallites of calcite and considerable amounts of amorphous calcium carbonate (ACC). However, the cuticle of the horseshoe crab Limulus polyphemus contains mainly alpha-chitin-protein fibers, but no crystalline biominerals. In this study, X-ray pole figure analysis was performed to investigate the preferred orientation (crystallographic texture) of calcite and alpha-chitin, in the crustaceans, edible crab Cancer pagurus and american lobster Homarus americanus cuticles, with respect to their orientation relationship firstly, and their alignment with respect to the cuticle geometry secondly. The preferred orientation of alpha-chitin in the cuticle of horseshoe crab was also determined. Synchrotron wide-angle X-ray diffraction (XRD) was employed in studying the texture of samples from different parts of the exoskeleton. The importance of the crystallographic textures in biological materials lies in its direct relationship with its possible role of the contained macromolecules in controlling the epitaxy of the minerals during the biomineralization process. Furthermore, it reveals information about the topological texture, which is represented by the fibers' arrangements in the cuticle. This study shows that crab and lobster cuticles reveal a strong crystallographic texture and preferred orientation correlation between the orientation distribution of calcite and alpha-chitin. It was observed that the c-axis of the hexagonal calcite and the b-axis of the orthorhombic alpha-chitin are firstly preferentially aligned parallel to each other and secondly oriented along the surface normal, whereas the other axes are co-aligned with respect to each other throughout the cuticle plane. The observed spatial rotational freedom of the c-axis of alpha-chitin (fiber axis) represents the twisted plywood structure of the alpha-chitin fibers as observed in scanning electron microscopy (SEM). Additionally, a smaller fraction of the alpha-chitin unit cells in lobster and crab cuticle is oriented with their fiber axis toward the cuticle surface, which was also observed in the SEM images of the cuticle. The texture of the horseshoe crab contains two strong fiber texture components perpendicular to each other. The first one is characterized by a very strong crystallographic orientation of b-axis parallel to the surface normal, whereas the other axes are co-aligned through the cuticle surface plan, which is similar to the observed strong fiber texture component in crustacean cuticle. The second fiber texture component is characterized by a strong crystallographic orientation of c-axis (alpha-chitin fiber direction) with a preferred alignment pointing parallel to the cuticle plane. The synchrotron X-ray crystallographic texture results gave for the first time a statistical description of the orientation relationship between the organic and inorganic components in arthropod cuticle, consistent with the morphological texture determined by SEM. This result strongly suggests that the fibrous structure of alpha-chitin assists the growth of calcite crystals in crustacean cuticle by functioning directly or indirectly as a template for nucleation and subsequent growth of calcite on the basis of oriented nucleation and epitaxial growth of calcite.","abstract_has_math":false,"creators":["Sawalmih, Ali al-"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Raabe, Dierk"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2007,"date_issued":"2007","date_published":"2007","updated_at":"2026-07-30T19:43:28Z","subjects":["info:eu-repo/classification/ddc/620","Kutikula","Röntgenweitwinkelstreuung","Calcit","Chitin","Gliederfüßer","Textur","Synchrotron","Ingenieurwissenschaften","cuticle","wide-angle X-ray diffraction","calcite","arthropods","texture"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124122%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124122%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124122%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/62558","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Raabe, Dierk"]},{"key":"dc:creator","label":"Author","values":["Sawalmih, Ali al-"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2007"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-20838"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/620","Kutikula","Röntgenweitwinkelstreuung","Calcit","Chitin","Gliederfüßer","Textur","Synchrotron","Ingenieurwissenschaften","cuticle","wide-angle X-ray diffraction","calcite","arthropods","texture"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/62558","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124122%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Arthropods, which include the crustaceans (e.g. crabs, lobsters, isopods), insects, arachnids (e.g. spiders, scorpions, ticks, mites), and several lesser groups, account for approximately 80 percent of all known animal species. The outer covering of these animals is referred to as exoskeleton or cuticle, and it covers the entire body of the animal. It has remarkable mechanical properties which provide structural support to the body, armor against loads that are externally imposed by predators. It also enables mobility through the formation of joints and attachment sites for muscles. Crustacean cuticle contains alpha-chitin-protein organic fibers associated with crystallites of calcite and considerable amounts of amorphous calcium carbonate (ACC). However, the cuticle of the horseshoe crab Limulus polyphemus contains mainly alpha-chitin-protein fibers, but no crystalline biominerals. In this study, X-ray pole figure analysis was performed to investigate the preferred orientation (crystallographic texture) of calcite and alpha-chitin, in the crustaceans, edible crab Cancer pagurus and american lobster Homarus americanus cuticles, with respect to their orientation relationship firstly, and their alignment with respect to the cuticle geometry secondly. The preferred orientation of alpha-chitin in the cuticle of horseshoe crab was also determined. Synchrotron wide-angle X-ray diffraction (XRD) was employed in studying the texture of samples from different parts of the exoskeleton. The importance of the crystallographic textures in biological materials lies in its direct relationship with its possible role of the contained macromolecules in controlling the epitaxy of the minerals during the biomineralization process. Furthermore, it reveals information about the topological texture, which is represented by the fibers' arrangements in the cuticle. This study shows that crab and lobster cuticles reveal a strong crystallographic texture and preferred orientation correlation between the orientation distribution of calcite and alpha-chitin. It was observed that the c-axis of the hexagonal calcite and the b-axis of the orthorhombic alpha-chitin are firstly preferentially aligned parallel to each other and secondly oriented along the surface normal, whereas the other axes are co-aligned with respect to each other throughout the cuticle plane. The observed spatial rotational freedom of the c-axis of alpha-chitin (fiber axis) represents the twisted plywood structure of the alpha-chitin fibers as observed in scanning electron microscopy (SEM). Additionally, a smaller fraction of the alpha-chitin unit cells in lobster and crab cuticle is oriented with their fiber axis toward the cuticle surface, which was also observed in the SEM images of the cuticle. The texture of the horseshoe crab contains two strong fiber texture components perpendicular to each other. The first one is characterized by a very strong crystallographic orientation of b-axis parallel to the surface normal, whereas the other axes are co-aligned through the cuticle surface plan, which is similar to the observed strong fiber texture component in crustacean cuticle. The second fiber texture component is characterized by a strong crystallographic orientation of c-axis (alpha-chitin fiber direction) with a preferred alignment pointing parallel to the cuticle plane. The synchrotron X-ray crystallographic texture results gave for the first time a statistical description of the orientation relationship between the organic and inorganic components in arthropod cuticle, consistent with the morphological texture determined by SEM. This result strongly suggests that the fibrous structure of alpha-chitin assists the growth of calcite crystals in crustacean cuticle by functioning directly or indirectly as a template for nucleation and subsequent growth of calcite on the basis of oriented nucleation and epitaxial growth of calcite."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University III, 135 S. : Ill., graph. Darst. (2007). = Aachen, Techn. Hochsch., Diss., 2007"]},{"key":"dc:title","label":"Title","values":["Crystallographic texture of the arthropod cuticle using synchrotron wide angle X-ray diffraction"]}]}],"canonical_facts":{"dc:contributor":["Raabe, Dierk"],"dc:coverage":["DE"],"dc:creator":["Sawalmih, Ali al-"],"dc:date":["2007"],"dc:description":["Arthropods, which include the crustaceans (e.g. crabs, lobsters, isopods), insects, arachnids (e.g. spiders, scorpions, ticks, mites), and several lesser groups, account for approximately 80 percent of all known animal species. The outer covering of these animals is referred to as exoskeleton or cuticle, and it covers the entire body of the animal. It has remarkable mechanical properties which provide structural support to the body, armor against loads that are externally imposed by predators. It also enables mobility through the formation of joints and attachment sites for muscles. Crustacean cuticle contains alpha-chitin-protein organic fibers associated with crystallites of calcite and considerable amounts of amorphous calcium carbonate (ACC). However, the cuticle of the horseshoe crab Limulus polyphemus contains mainly alpha-chitin-protein fibers, but no crystalline biominerals. In this study, X-ray pole figure analysis was performed to investigate the preferred orientation (crystallographic texture) of calcite and alpha-chitin, in the crustaceans, edible crab Cancer pagurus and american lobster Homarus americanus cuticles, with respect to their orientation relationship firstly, and their alignment with respect to the cuticle geometry secondly. The preferred orientation of alpha-chitin in the cuticle of horseshoe crab was also determined. Synchrotron wide-angle X-ray diffraction (XRD) was employed in studying the texture of samples from different parts of the exoskeleton. The importance of the crystallographic textures in biological materials lies in its direct relationship with its possible role of the contained macromolecules in controlling the epitaxy of the minerals during the biomineralization process. Furthermore, it reveals information about the topological texture, which is represented by the fibers' arrangements in the cuticle. This study shows that crab and lobster cuticles reveal a strong crystallographic texture and preferred orientation correlation between the orientation distribution of calcite and alpha-chitin. It was observed that the c-axis of the hexagonal calcite and the b-axis of the orthorhombic alpha-chitin are firstly preferentially aligned parallel to each other and secondly oriented along the surface normal, whereas the other axes are co-aligned with respect to each other throughout the cuticle plane. The observed spatial rotational freedom of the c-axis of alpha-chitin (fiber axis) represents the twisted plywood structure of the alpha-chitin fibers as observed in scanning electron microscopy (SEM). Additionally, a smaller fraction of the alpha-chitin unit cells in lobster and crab cuticle is oriented with their fiber axis toward the cuticle surface, which was also observed in the SEM images of the cuticle. The texture of the horseshoe crab contains two strong fiber texture components perpendicular to each other. The first one is characterized by a very strong crystallographic orientation of b-axis parallel to the surface normal, whereas the other axes are co-aligned through the cuticle surface plan, which is similar to the observed strong fiber texture component in crustacean cuticle. The second fiber texture component is characterized by a strong crystallographic orientation of c-axis (alpha-chitin fiber direction) with a preferred alignment pointing parallel to the cuticle plane. The synchrotron X-ray crystallographic texture results gave for the first time a statistical description of the orientation relationship between the organic and inorganic components in arthropod cuticle, consistent with the morphological texture determined by SEM. This result strongly suggests that the fibrous structure of alpha-chitin assists the growth of calcite crystals in crustacean cuticle by functioning directly or indirectly as a template for nucleation and subsequent growth of calcite on the basis of oriented nucleation and epitaxial growth of calcite."],"dc:identifier":["https://publications.rwth-aachen.de/record/62558","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124122%22"],"dc:language":["eng"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-20838"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University III, 135 S. : Ill., graph. Darst. (2007). = Aachen, Techn. 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