Parasitism on Ordovician Chitinozoa

Borings are common in chitinozoans. They are cylindrical or conical, widening towards the outer surface of the vesicle wall. It is suggested that the cylindrical borings were probably caused by bacteria. Actinomycota and lower Fungi including at least Chytridiomycota, and the conical borings mainly by chytridia. Two types of spore-like bodies, operculate and non-operculate, have been found in situ on two chitinozoan species. The spore-like bodies are of about the same size as the supposed boring organisms in chitinozoans but are never found in association with the borings. They are interpreted as cysts of ectoparasitic nannoorganisms that resemble ciliates and amoebae, and their possible use for determining the biochemical composition of the chitinozoans is briefly discussed.