ABSTRACT
The tentacles of shallow-water, north European dendrochirote holothurians have been compared at an ultrastructural level using scanning electron microscopy (S.E.M.). Apparent differences between specimens of the same species are mostly ascribable to contraction of the tentacles and the loss of the fuzzy coat and cuticle in some specimens. In Ocnus regeneration of tentacles is seen as a possible source of intraspecific variation in tentacle texture. All the species studied possess papillae and cilia on their tentacles. Differences were found in the fine structure of the tentacles between Thyone species and the other species studied. Structures seen on Duasmodactyla tentacle trunks are considered to have a sensory function. The structural differences and, in some cases, lack of them are discussed in relation to interspecific competition.
