Estimation and interpretation of egg provisioning in marine invertebrates.

Per-offspring maternal investment is an integral part of life-history theory. To understand the evolution of per-offspring maternal investment in marine invertebrates, a number of mathematical models have been developed. These models examine how selection affects the proportion of maternally derived egg energy used to produce a newly metamorphosed juvenile (s) and make predictions about the distribution of s in nature.

DEVELOPMENTAL CONSEQUENCES OF AN EVOLUTIONARY CHANGE IN EGG SIZE: AN EXPERIMENTAL TEST.

Larvae of two species of sea urchins (Strongylocentrotus droebachiensis and S. purpuratus) differ in initial form and in the rate of development. To determine whether these differences are attributable to the large interspecific difference in egg size, we experimentally reduced egg size by isolating blastomeres from embryos.

CYPHONAUTES' CILIARY SIEVE BREAKS A BIOLOGICAL RULE OF INFERENCE.

Biologists routinely assume that a mechanism demonstrated in one organism will be found in others in which form, function, ancestry, and physical parameters are similar. These criteria failed to predict the feeding mechanism of the cyphonautes larva of bryozoans. Larval and adult bryozoans feed with cilia similar in size and distribution, with similar current velocities, and similar Reynolds numbers.