Carbonate biomineralization in marine organisms normally occurs as three distinct types, known respectively as: “controlled”, “induced” and “influenced”. Among invertebrates, reef-building tubeworms belonging to the family Cirratulidae appear to provide us with the first known example of “double-phased” biomineralization as they simultaneously combine controlled and induced biomineralization types in the formation process of their tubes. Miocene (Diplochaetetes) and Recent (Dodecaceria) bioconstructions from southern Peru were studied to investigate the mineral structure of cirratulids: the primary ultrastructure of the tube walls points to controlled biomineralization, while the “intertube” areas between walls filled by a calcareous matrix, frequently with agglutinating extraneous sand grains, are deemed the product of an induced biomineralization. The means by which this double biomineralization process occurs have yet to be described in detail. This study is therefore focused on this aspect by examining cirratulid aggregates via optical microscopy, epifluorescence, SEM, EDS analyses and morphometry. Results have also been statistically evaluated in order to detect the possible relationship between the size and chemical composition of the skeletal component and the morphology of the bioconstructions which in turn hints to environmental parameters. Both fossils and recent specimens show similar correlations among composition and morphometric parameters, suggesting that the development/evolution of these bioconstructions is presumably unaffected by environmental chemical/physical conditions. The peculiar double phased biomineralization system of cirratulids seems not evolved since the Eocene, when they appeared.
DOUBLE-PHASED BIOMINERALIZATION PROCESSES IN MARINE INVERTEBRATES: THE EXAMPLE OF CIRRATULIDS (POLYCHAETA, ANNELIDA) FROM SOUTHERN PERU
Alberto COLLARETASecondo
;Giulia BOSIOPenultimo
;
2023-01-01
Abstract
Carbonate biomineralization in marine organisms normally occurs as three distinct types, known respectively as: “controlled”, “induced” and “influenced”. Among invertebrates, reef-building tubeworms belonging to the family Cirratulidae appear to provide us with the first known example of “double-phased” biomineralization as they simultaneously combine controlled and induced biomineralization types in the formation process of their tubes. Miocene (Diplochaetetes) and Recent (Dodecaceria) bioconstructions from southern Peru were studied to investigate the mineral structure of cirratulids: the primary ultrastructure of the tube walls points to controlled biomineralization, while the “intertube” areas between walls filled by a calcareous matrix, frequently with agglutinating extraneous sand grains, are deemed the product of an induced biomineralization. The means by which this double biomineralization process occurs have yet to be described in detail. This study is therefore focused on this aspect by examining cirratulid aggregates via optical microscopy, epifluorescence, SEM, EDS analyses and morphometry. Results have also been statistically evaluated in order to detect the possible relationship between the size and chemical composition of the skeletal component and the morphology of the bioconstructions which in turn hints to environmental parameters. Both fossils and recent specimens show similar correlations among composition and morphometric parameters, suggesting that the development/evolution of these bioconstructions is presumably unaffected by environmental chemical/physical conditions. The peculiar double phased biomineralization system of cirratulids seems not evolved since the Eocene, when they appeared.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
