1. 1. Egg diameters (mm) of the spatangoid echinoids Abatus shackletoni, Abatus nimrodi and the asteroids Notasterias armata, Diplasterias brucei, and Perknaster fuscus antarcticus were 1.28, 1.97, 3.54, 2.80 and 1.20, respectively. A. shackletoni, A. nimrodi, N. armata and D. brucei, brood their embryos to a juvenile stage; P. fuscus antarcticus apparently is a broadcast spawner with pelagic lecithotrophic larvae. 2. 2. Eggs were composed primarily of protein (33-53%) and lipid (36-59%). Juveniles had higher levels of insoluble protein and ash due to the formation of structural and skeletal material. 3. 3. There was little decrease in the amount of energy from egg to juvenile during development. This supports the hypothesis that large egg size in marine invertebrates with lecithotrophic development is more important in producing a large juvenile than in the provision of a large amount of energy for development. 4. 4. Comparisons of reproductive output and reproduotive effort in echinoderms with lecithotrophic development reveal a high degree of interspecific variability. 5. 5. This variability is related to the differential allocation of energy to somatic and gametic tissues based on differences in functional morphologies. 6. 6. Variable reproductive efforts in species with lecithotrophic development confound comparisons with species with planktotrophic development and make tests of energetic hypotheses for alternate life-history stategies in marine invertebrates difficult. © 1986.