Intercolony fusion suggests polyembryony in Paleozoic fenestrate bryozoans

Abstract

Fusion occurred between pairs of conspecific colonies of Permian fenestrate bryozoans that were of approximately equal radius at time of contact. In contrast, no fusion occurred in pairs of conspecific colonies that were of unequal radius at time of contact. It is suggested that histologically compatible colonies developed from larvae that settled essentially simultaneously and that the larvae were siblings, lecithotrophic with low mobility, and of the same genotype (i.e., polyembryonic). Thus polyembryony appears to have existed as a reproductive “strategy” for at least 275 Myr, and its scarcity in modern taxa cannot be due to recentness of evolution.