Description
Heliozoa with axonemes terminating at or near nuclei; nucleus may be large and central (one genus) or small and numerous and located towards the periphery of the cell. Axopodia taper from base to tip. Microtubu les within the axonemes in double interlocking coils. Mitochondrial cristae are tubular. With 2 types of simple extrusomes which cause prey to adhere to the heliozoan so it can be ingested (Patterson and Hausmann , 1 9 81 ) . Cells often fuse around a large accumulation of food. Reproduction mainly by binary fission , but autogamy (within one diploid cell giving rise to two haploid cells which fuse again) occurs in a cyst. Trophic cells are naked; cysts are surrounded by a layer of siliceous elements. Common and widespread in freshwater , also in soil , occasionally encountered in brackish and marine environments . Affinities unclear, but may lie with the stramenopiles (Patterson , 1986) . Two genera. References: Mignot (1979, 1980a, 1980b, 1984) and Patterson (1979) . 1. With a central nucleus .. ........... .. Actinophrys 1'. Cell with several peripheral nuclei. .... ...... .... .. . ... ...... ............ ....... ... ... ......... Actinosph
Type species
Figures
No linked figures.
Raw text
Heliozoa with axonemes terminating at or near nuclei; nucleus may be large and central (one genus) or small and numerous and located towards the periphery of the cell. Axopodia taper from base to tip. Microtubu les within the axonemes in double interlocking coils. Mitochondrial cristae are tubular. With 2 types of simple extrusomes which cause prey to adhere to the heliozoan so it can be ingested (Patterson and Hausmann , 1 9 81 ) . Cells often fuse around a large accumulation of food. Reproduction mainly by binary fission , but autogamy (within one diploid cell giving rise to two haploid cells which fuse again) occurs in a cyst. Trophic cells are naked; cysts are surrounded by a layer of siliceous elements. Common and widespread in freshwater , also in soil , occasionally encountered in brackish and marine environments . Affinities unclear, but may lie with the stramenopiles (Patterson , 1986) . Two genera. References: Mignot (1979, 1980a, 1980b, 1984) and Patterson (1979) . 1. With a central nucleus .. ........... .. Actinophrys 1'. Cell with several peripheral nuclei. .... ...... .... .. . ... ...... ............ ....... ... ... ......... Actinosph