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Record: oai:ARNO:504282

AuthorS. van der Spoel
TitleStrobilation in a mollusc; the development of aberrant stages in Clio pyramidata Linnaeus, 1767 (Gastropoda, Pteropoda)
JournalBijdragen tot de Dierkunde
AbstractThe occurrence of aberrant stages in the protandric hermaphrodite Clio pyramidata is considered in relation to the sexual cycle of this species. The anatomy of the juveniles, males and females is shortly discussed especially with regard to their sexual organs. The anatomy of the developing (the normal-complete) and of the growingaberrant stage is briefly reviewed. It is shown that the aberrant stage is formed by strobilation of a normal specimen, probably as a result of less favourable environmental conditions. As the most important conclusions it can be stated that: 1) the aberrant stage described by van der Spoel (1962) is a normal stage in the life cycle; 2) the aberrants are most abundant in the population in the months before the reproductive peaks; 3) the aberrants seem to occur more frequently when environmental conditions become less favourable; 4) the aberrants develop from specimens in the female phase; 5) the aberrants develop into male specimens; 6) the aberrants arise by strobilation of a normal specimen; 7) the animal, which gives rise by strobilation to an aberrant, is after strobilation an asexual shell-less specimen; 8) the strobilation points to an evolutionary relation between worms and molluscs.
Document typearticle
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