Post‐planktonic development ofPinnotheres novaezelandiaeinPerna canaliculusfrom Wellington Harbour was found to be similar to that of the other members of the Pinnotheridae. The invasive stage was not found. The sequence of stages found within mussels was an unknown number of pre‐hard stages occurring in both sexes, then a hard‐shell stage; the males show no further morphological changes after this point, but the females mature through a further four soft‐shell developmental stages. No similar post‐hard soft stage occurs in males, although previous workers reported it in maleP. pisum.