Size and organic content of eggs of echinoderms and other invertebrates as related to developmental strategies and egg eating

In 7 species of echinoderms, 2 species of polychaetes, and 1 species of oyster with feeding larvae, larger eggs were found to contain more organic matter. Although organic matter per egg increases with egg diameter or volume, it is not proportionate to egg volume, because small eggs have more concentrated organic matter than larger eggs. There appear to be differences among higher taxa in the minimum size of freely spawned eggs. These differences could result from different relationships between mortality and reduced egg size arising from differences between larval feeding mechanisms or differences in size at metamorphosis. An egg has more than five times the organic matter of a diatom of the same size and is thus a bigger meal for suspension feeders.