SICB Division of Invertebrate Zoology (DIZ)

DIZ Researchers Database Entry

Richard R. Strathmann

Functional Requirements and Constraints
Most of my research is on functional requirements and constraints for embryos, larvae, and juveniles of marine invertebrates. I am interested in why the beautiful and diverse patterns of development have evolved as they have instead of in other ways. Research by my students and me includes constraints on protecting aggregations of embryos, evolution of development rates, larval feeding mechanisms, plasticity in larval forms, and the costs and benefits of larval dispersal.
One recent interest, made possible by collaboration with Danny Grünbaum, is compromises between swimming and feeding that affect larval form and behavior. Extending ciliated bands into long loops increases a larva's ability to capture scarce planktonic food, but Danny's model predicts that this form decreases stability of swimming in moving water, in which gradients of velocity turn the larvae. Observations on movements of sand dollar larvae (front and top views in A and B) confirm the predictions from Danny's mathematically modeled larva (in C). In a chamber with flow upward on one side and downward on the other, larvae that are swimming upward are tilted, move across flow lines into the downward currents, and then are carried downward faster than they can swim upward. Extensions of ciliated bands that make these larvae good eaters appear to make them poorer swimmers.