ANTARCTIC TINTINNIDS - THEIR ECOLOGY, MORPHOLOGY, ULTRASTRUCTURE AND POLYMORPHISM

Ciliates from the suborder Tintinnina are the cosmopolitan organisms l iving mainly in the upper parts of oceans and seas. In consideration o f their morphology and role in food web they are an interesting materi al for researches. Besides the attributes typical for all Ciliata they have some internal and external features typical only for this group. I started my examination of Antarctic tintinnids from the analysis of species composition and seasonal succession in waters of Admiralty Ba y and the Weddell Sea (Wasik and Mikolajczyk 1990, 1994a). Cymatocylis convallaria, with a short lorica horn dominated during the austral su mmer, while C. affinis with the long aboral part of the lorica dominat ed during the winter. In spring and fall the transition in loricae sha pe from one form to the other was observed, a finding which may indica te that some previously separate species are in fact only polymorphs o f one species. To furnish evidence for this suggestion, protoplast mor phology and ultrastructure were compared (Wasik and Mikolajczyk 1991, 1992) with special emphasis on the pattern of somatic and oral ciliatu re (Wasik and Mikolajczyk 1994); the results unequivocally showed that both C. affinis and C. convallaria are indeed polymorphic forms of on e species. Tintinnids are known as ciliates with a protoplast protecte d by different forms of loricae. Depending on the species, the lorica might be hyaline and partially or totally agglutinated by mineral and/ or biological particles. The possibility that tintinnids select partic les during lorica formation is still being debated, but I tried to add ress this issue. The results indicated that particles are selected by them. The investigations were not limited only to an examination of th e material agglutinating the loricae, but included analyses of the mor phology and microarchitecture of the lorica wall (Wasik et al, 1996; 1 997a,b). On the base of electron scanning and transmission microscopie s it appeared that depending on species lorica surface morphology reve aled differences, while wall microarchitecture is very much the same i n a form of honeycomb.