Cloudina

Classification

Cloudina was originally classified in 1972 as a member of the Cribricyathea, a class known from the Early Cambrian. Glaessner (1976) accepted this classification and also proposed that Cloudina was similar to the annelid worms, particularly serpulidpolychaetes. However, Hahn & Pflug (1985) and Conway Morris et al.. (1990) doubted both Germs' and Glaessner's suggested relationships, and were unwilling to classify it to anything more than its own family, Cloudinidae. Some specimens of Cloudina hartmannae display budding, which implies asexual reproduction. On this basis Grant (1990) classified Cloudina as a coral-like cnidarian. Since the tubes had an open base, creating a single living space rather than a series of separate chambers, Cloudina is more likely to be a stem group polychaete worm, in other words an evolutionary "aunt" or "cousin" of more recent polychaetes. This interpretation is reinforced by the even distribution of bore-holes made by predators. However, as with so many Ediacaran life forms, there is great debate surrounding its position in the tree of life, and classification between the kingdom and family level may be unwise.