Metamorphosis in the Lobster Homarus (Decapoda): a Review

A homarid lobster hatches as a prelarva and then molts successively through three larval instars (stages I, II, and III), one postlarval stage (IV), and numerous juvenile stages. Between the larval and the postlarval stages their anatomy undergoes major changes as the anatomical features characteristic of larval forms are replaced by those found on juveniles and adults. Physiology, ecology, and ethology also change progressively through stages IV and V, during which the lobster shifts from the planktonic behavior of the larva to the benthic existence of the juvenile and adult. This transition from larva to postlarva, specifically the molt from stage III to stage IV, is a true metamorphosis in which the eyestalk neuroendocrine tissue seems to be involved.