Changes in Rates of Increase in Size and of Exoskeletal Production during Old Age in the Isopod Ligia oceanica (L.)

Abstract

THE male isopod Ligia oceanica (L.) goes on moulting and growing even when its spermatogenesis has come to an end^1–4. The coexistence of growth and senescence seems to me an unexpected finding in a higher metazoon. It is possible to split up the postpuberal growth period of Ligia into the sexually mature stage and the senescent stage, both of which are states of morpho-physiological equilibrium, and an intermediate transitional phase. The term ‘stage’ is here used as equivalent to the French term étape and is composed of several ‘stadia’ separated by a moult. In the sexually mature stage the gonads are fully developed, in the senescent stage they are degenerated. The transitional phase is characterised by various degrees of testicular degeneration.