Reproduction and rapid growth in a deep-sea aplacophoran mollusc, Prochaetoderma yongei

Abstract

Prochaetoderma yongei, an aplacophoran mollusc with a wide geographic distribution between 450 and 2200 m depth and high densities in the North American Basin, grows to adult size within 2 mo and sexual maturity w i t h 1 yr. Gametogenesis was asynchronous within individuals from a single sled-trawl sample. Periods of increased recruitment and numbers of ripe individuals occur; whether these recurrent periods are irregular or cyclic at regular intervals is not known. Males usually outnumber females in all size classes. The peak class in length-frequency distributions contains individuals less than 1 yr old. Repopulation of a disturbed area by this species may require about a decade. The rapid growth to maturity by P. yongei and its ability to colonize are attributes adapted to transient or disturbed enwonments, but its low egg numbers and lack of synchrony in egg development are not.