Originally published in Biological Bulletin and used with permission.


Larvae of the gastropod Haliotis rufescens are classified as "nonfeeding" because they cannot capture particular foods. However, for only 1 out of 5 independent cultures was a net decrease observed in dry organic weight during the complete period of larval development (5 to 7 days). In fact, there were net increases in dry organic weight from the oocyte (day 0) to the newly formed veliger larvae (2-day-old). These weight increases during early development could be explained by increases in the amounts of specific biochemical components of the larvae, relative to oocytes. The metabolic rates of larvae were measured (oxygen consumption) and used to compare (i) the reuired energy for development with (ii) the energy supplied from the catabolism of biochemical reserves. This analysis revealed that the cost of development for larvae could not be explained by the rates of use of the energy stores initially present in the oocyte. Larvae, from two independent cultures, could only supply 25% or 71% of their energy requirements by the use of internal reserves. Larvae of H. rufescens cannot use particulate foods and, thus, this energy resources cannot be invoked. Estimates of the contribution that dissolved organic material in seawater could provide to larvae, showed that this pool of exogenous material could supply the missing energy. It is suggested that "nonfeeding" larvae can feed, but that their only available nutrients are in a dissolved form.


Biology | Physiology