Functions of the canal system in the rotaliid foraminifer, Heterostegina depressa

Advanced fossil and living rotaliacean foraminifera are characterized by canal systems located within the walls of their plurilocular calcareous tests. Although these canals were described in detail during the nineteenth century, there biological functions have remained obscure. A study of the recent nummulitid, Heterostegina depressa, has now illuminated the role of the canal system and allowed us to interpret similar structures seen in related foraminifera of Tertiary age. It proves to be a structure of fundamental importance for locomotion, growth, excretion, reproduction and protection.