Agglomerated loricae of the tintinnids <i>Codonella, Codonellopsis</i> and <i>Dictyocysta</i> from North Atlantic, tropical Pacific and Southern Ocean waters.

Abstract

Some 30 species of planktonic tintinnids agglomerate coccoliths and diatom fragments on to their loricae, which have fascinated scientists for centuries. We here provide semi-quantitative scanning electron microscopic observations on tintinnid lorica agglomerations by the small Southern Ocean <i>Codonellopsis</i> cf. <i>soyai</i> Hada, intermediate sized North Atlantic <i>Codonellopsis pusilla</i> (Cleve) Kofoid and Campbell, and larger Southern Ocean <i>Dictyocysta lepida</i> Ehrenberg and tropical Pacific <i>Codonella galea</i> Haeckel. Smaller tintinnids appeared to non-selectively use ubiquitous <i>Emiliania huxleyi</i> liths, but when absent could shift to ambient diatom fragments, while larger tintinnids preferentially used heavier coccoliths of <i>Calcidiscus, Coccolithus</i> and <i>Helicosphaera</i> adding up to an estimated 25% extra lorica weight. Lorica agglomerations appeared more prominent in colder waters compared to warmer tropical waters. Selective feeding in tintinnids is closely linked to their swimming behavior, and possible benefits from agglomerated loricae for ballasting and slowing of swimming speed are discussed.