Sensory elements and innervation in the freshwater bryozoan Cristatella mucedo lophophore.

Abstract

The bryozoans (phylum Bryozoa), widespread inseas and fresh water bodies, are colonial filterfeeders,with their colonies formed of connected zooids. Alarge part of zooids (all of them in the freshwater bryozoans) have their individual foodgathering organ,the lophophore. They feed by means of the activity oflophophore tentacles and their cilia, which create adownward water flow conveying food particles to themouth [1, 2]. The mouth in freshwater bryozoans iscovered with a lobe formed of the body wall, the epistome, the role of which in their foraging behavior isstill vague.Although the bryozoans have long been studied,the data on their nervous system are rather scarce. Theinformation about neuronal background of zooidbehavior are confined to the research dating back tothe early 20th century based on supravital stainingwith methylene blue [3, 4], as well as the ultrastructural studies of four marine and one freshwater bryozoans. However, these papers describe only the generaltentacle ultrastructure and localization of the nervecords [5–9]. The goal of this study was to investigatethe nervous system in tentacles of the freshwater bryozoans as exemplified of