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How to solve the problem of inherited behavior patterns and increase the sustainability of technological civilization
Get PDFOccurrence, formation and function of organic sheets in the mineral tube structures of Serpulidae (polychaeta, Annelida).
No full textA scanning electron microscopy study of organic sheets in serpulid tube mineral structures was carried out to discern their function, formation and evolution. The organic sheets may have some taxonomic value in distinguishing the two major clades of serpulids previously identified. The organic sheets in the mineral tube structure occur only in certain taxa belonging to clade A, but not all species in clade A have them. Organic sheets are best developed in genus Spirobranchus. One could speculate that organic sheets have evolved as an adaption to further strengthen the mechanical properties of the tubes in clade A, which contains serpulids with the most advanced mineral tube microstructures. The organic sheets are presumably secreted with at least some mineral phase
Phosphatic Biomineralization in Scyphozoa (Cnidaria): A Review
No full textPhosphatic biomineralization is unknown in modern species of Scyphozoa (Cnidaria). However, some extinct groups of Scyphozoa, such as conulariids and Sphenothallus, were capable of secreting phosphatic exoskeletons. Both conulariids and Sphenothallus used apatite to improve the mechanical properties of their skeletons, which offered better protection than the non-biomineralized periderms. The skeletons of conulariids and Sphenothallus have a lamellar microstructure. The shell lamellae of conulariids are often pierced by tiny pores. Several apatitic mineral structures have been described in conulariids and Sphenothallus, including plywood-like structures. Different lattice parameters of the apatite indicate that the biomineralization mechanisms of the phosphatic cnidarians Sphenothallus and conulariids differed from each other
The Role of Aragonite in Producing the Microstructural Diversity of Serpulid Skeletons
No full textAragonite plays an important role in the biomineralization of serpulid polychaetes. Aragonitic structures are present in a wide range of serpulid species, but they mostly belong to one clade. Aragonitic structures are present in a wide range of marine environments, including the deep ocean. Aragonitic tube microstructures were studied using a scanning electron microscope. X-ray powder diffraction was used to identify the aragonite. Aragonite is used to build five different types of microstructures in serpulid tubes. The most common aragonitic irregularly oriented prismatic structure (AIOP) is also, evolutionarily, the most primitive. Some aragonitic microstructures, such as the spherulitic prismatic (SPHP) structure, have likely evolved from the AIOP structure. Aragonitic microstructures in serpulids are far less numerous than calcitic microstructures, and they lack the complexity of advanced calcitic microstructures. The reason why aragonitic microstructures have remained less evolvable than calcitic microstructures is currently unknown, considering their fit with the current aragonite sea conditions (Paleogene–recent)
Biomineralization of Polychaete Annelids in the Fossil Record
No full textTen distinct microstructures occur in fossil serpulids and serpulid tubes can contain several layers with different microstructures. Diversity and complexity of serpulid skeletal structures has greatly increased throughout their evolution. In general, Cenozoic serpulid skeletal structures are better preserved than Mesozoic ones. The first complex serpulid microstructures comparable to those of complex structures of molluscs appeared in the Eocene. The evolution of serpulid tube microstructures can be explained by the importance of calcareous tubes for serpulids as protection against predators and environmental disturbances. Both fossil cirratulids and sabellids are single layered and have only spherulitic prismatic tube microstructures. Microstructures of sabellids and cirratulids have not evolved since the appearance of calcareous species in the Jurassic and Oligocene, respectively. The lack of evolution in sabellids and cirratulids may result from the unimportance of biomineralization for these groups as only few species of sabellids and cirratulids have ever built calcareous tubes
Shell microstructure of<i>Cornulites</i><i>semiapertus</i>Öpik, 1930 and other early cornulitids from the Ordovician of North Estonia
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