Observations on the Microanatomy ofCoccolithus PelagicusandCricosphaera Carterae, With Special Reference to the Origin and Nature of Coccoliths and Scales

Abstract

Coccolith structure, mode of origin and arrangement on the cell surface have been investigated in two marine coccolithophorids,Coccolithus pelagicus(Wall.) Schiller andCricosphaera carterae(Braarud et Fagerland) Braarud, by means of light microscopy and electron microscopy of whole mounts and sections. The presence of flagellar bases inCoccolithus pelagicusis also demonstrated in spite of the fact that the cells of this phase of the life-history are non-motile. In both organisms the coccoliths are shown to be accompanied by unmineralized scales, details of which are illustrated; in particular, each coccolith is attached to the margin of an unmineralized oval plate which completely covers the central ‘pore’ on the side towards the subtending cell. Scales and coccoliths arise within the cisternae of the single Golgi body in a manner closely resembling the origin of scales in species ofChrysochromulina.It is therefore suggested that the coccoliths of the two taxa investigated can be interpreted as modified (and calcined) scale rims.