Phosphatic shell plate of the barnacle Ibla (Cirripedia): a bone-like structure.

The carbonate apatite crystals and the segmented structure of the shell plates of the barnacles in the genus Ibla distinguish them from the shell plates of all other barnacles, which are coherent calcitic structures. A detailed study of the hierarchical organization of one of the two shell plate types, the tergum, reveals a remarkably complex structure. Cylinders composed of a chitin-protein complex and nodes of plate-shaped crystals constitute the basic building blocks.

Transformation of amorphous calcium phosphate to crystalline dahillite in the radular teeth of chitons.

A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.

Mössbauer spectroscopy of iron-containing dermal granules from Molpadia intermedia.

Dermal granules containing hydrous ferric oxide cores from Molpadia intermedia were studied by Mössbauer spectroscopy from 1.5 to 300 K and in magnetic fields up to 80 kOersted at 4.2 K.

Minerals formed by organisms.

Organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere. The initial precipitates may differ from the form in which they are finally stabilized, or during development of the organism one mineral may substitute for another. Biogenic minerals commonly have attributes which distinguish them from their inorganic counterparts.

Evolutionary prerequisites for early Phanerozoic calcareous skeletons.

This paper develops the concept that the dramatic appearance of calcareous skeletons in the Lower Cambrian is directly related to the origin of refined mechanisms of intracellular modulation of calcium ion concentration. An homologous family of calcium modulated proteins has recently been discovered. These proteins contain "EF hands", involved in the maintenance of low concentrations of intracellular calcium and the informational use of calcium ion flow (Kretsinger, 1977).

Calcareous deposits in the renal sac of a molgulid tunicate.

Weddellite (calcium oxalate dihydrate) and calcite (anhydrous calcium carbonate phase) are components of concretions in the renal sac of the ascidian tunicate Molgula manhattensis. The presence of weddellite along with urate in the concretions suggests a resemblance to human kidney stones, although, unlike the latter, the concretions in Molgula do not seem to be pathologic deposits.

Characterization of 80-million-year-old mollusk shell proteins.

Fossil glycoproteins of the soluble organic matrix are present in an 80-million-year-old mollusk shell from the Late Cretaceous Period. Discrete molecular weight components, as determined by gel electrophoresis, are preserved. The fossil organic matrix was compared with the organic matrix of a living representative species of the same superfamily.

Vaterite: a mineralization product of the hard tissues of a marine organism (Ascidiacea).

X-ray diffraction and infrared absorption spectra show that the spicules of the common tropical ascidian, Herdmania momus, are mineralized with vaterite. These are the first strictly marine organisms known to normally precipitate vaterite. The biomineralization of vaterite may constitute another link between the urochordates and vertebrates.

Opal precipitation by marine gastropods (Mollusca).

The high silicon content of certain radular sites of the Patellacea (Mollusca, Gastropoda) is shown by infrared absorption spectrums to be fixed in the form of the mineral opal. Opal and goethite mineralize the cusps and bases of the teeth. The presence of opalized base plates only in the families Acmaeidae and Lepetidae appears to be of taxonomic significance.

Biologic precipitation of fluorite.

X-ray diffraction patterns show that the statoliths of marine mysid crustaceans are composed of fluorite, and that this mineral is also a principal phase of the gizzard plates of some tectibranch gastropods. A phosphatic phase is also indicated by chemical analyses in the gizzard plates, but its crystallochemical characterization has not been feasible by x-ray diffraction. The occurrence of fluorite in mysid statoliths confirms the earlier interpretations based on insufficient documentation.

Weddellite in a marine gastropod and in antarctic sediments.

The calcium oxalate dihydrate mineral, weddellite, has been identified in a microarchitectural component of the gizzard plates from the deepwater gastropod Scaphander cylindrellus. This is the first indication of nonpathologic precipitation of this mineral by an animal species. A new occurrence of weddellite in sediments from the Weddell Sea, Antarctica, is also reported, lending support to the earlier interpretation that the mineral is an authigenic constituent of the sediments in this area.

Lepidocrocite, an apatite mineral, and magnetic in teeth of chitons (Polyplacophora).

X-ray diffraction patterns show that the mature denticles of three extant chiton species are composed of the mineral lepidocrocite and an apatite mineral, probably francolite, in addition to magnetite. Each of the three minerals forms a discrete microarchitectural unit of the chiton denticles. This is the first indication that lepidocrocite is precipitated by marine organisms and an apatite mineral by chitons.

INVERTEBRATE FERRITIN: OCCURRENCE IN MOLLUSCA.

Ferritin, in both crystalline and paracrystalline forms, occurs in the columnar epithelial cells of the dorsal wall of the radula of the marine chiton Cryptochiton stelleri, order, Polyplacophora. The ferritin occurs in association with the magnetite of the radular teeth. It has been isolated and crystallized in the presence of cadmium sulfate.

Goethite in Radular Teeth of Recent Marine Gastropods.

The x-ray diffraction patterns of the denticle material from several species show that the material consists of the mineral goethite. This is the first indication that goethite is precipitated by marine invertebrates. The mineralogy of the denticle caps has biologic and geologic implications.