PRATT, M.C.; Duke University, Durham, NC: It�s where you put your mouth that matters: how the location of feeding zooids within a colony affects ingestion rate in bryozoans.

While there is a wide diversity of colonial animals, very similar colony growth forms seem to have evolved convergently across taxa. Is there a functional reason why these similar growth forms evolved? What selection pressures may have played a role in shaping colony form? Bryozoan colonies of different forms show specific patterns in the location of their feeding zooids. Not all zooids are capable of feeding; some species of bryozoans have many other types of zooids (reproductive, defensive, structural, etc.). Optimizing the location of feeding zooids in a colony could affect overall colony feeding success and strongly shape colony form. In this study, I investigated how feeding performance varies as a function of feeding zooid location. For two species of bryozoans (Membranipora membranacea and Bugula pacifica), I compared the ingestion rate for zooids within a colony (e.g. upstream versus downstream, edge versus middle) as well as for zooids within a colony versus those that were isolated outside of the colony. Flow visualization (using particle image velocimetry) was also performed on the different treatments in order to understand the variation in feeding performance between zooids in different locations. I found that zooid location does affect feeding performance, which suggests that variation in feeding performance of zooids in different locations may have played a role in selecting for certain colony growth forms and where the feeding zooids are located in those forms.