A cyphonautes larva (Bryozoa: Gymnolaemata) from the Bellingshausen Sea, Antarctica

Bryozoans are an important component of the sessile, suspension-feeding fauna on the Antarctic continental shelf, (Knox & Cameron, 1970; Dell, 1972; Winston, 1983; Winston & Heimberg, 1988). Antarctic bryozoan faunas are systematically diverse, and display a broad range of colony morphotypes; they include fast-growing, short-lived species and long-lived perennials (Winston & Heimberg, 1988). Very little is presently known about the reproductive biology of Antarctic bryozoans, although it seems that a preponderance of species brood lecithotrophic larvae with a short, free-swimming phase. Planktotrophic larvae with a free-swimming phase of several weeks occur in a variety of gymnolaemate families, principally distributed in temperate coastal waters, and most often associated with specialized microhabitats or substrates. This type of larva, referred to as a cyphonautes (Zimmer & Woollacott, 1977), has not previously been reported from polar seas, and its occurrence in the Bellingshausen Sea, Antarctica, is thus of considerable interest.

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