Developmental arrest during larval life and life-span extension in a marine mollusc.

The length of larval life in the nudibranch Phestilia sibogae is determined by a chance encounter with a specific metamorphic stimulus associated with the post-larval benthic habitat. A developmental hiatus begins at the onset of larval metamorphic competence and ends at metamorphosis; aging is suspended during this hiatus. Because the duration of post-larval life is unaffected by the duration of larval life, total life-span varies with the length of the larval period. Developmental control of the timing of expression of life-history stages is an important factor regulating aging and senescence in animals with complex life cycles.