Radiolarian protozoan (Podocyrtis mitra) Science Image

Ref: rad014c



Radiolarian. Coloured scanning electron micrograph (SEM) of the test (skeleton) of a Podocyrtis cothurnata, a type of radiolarian protozoan. Radiolarians build these hard, mineral skeletons around themselves as they float in warm seas with other plankton. They extend their protoplasm as pseudopodia (false feet) through pores in the shell to feed on tiny organisms. The radiolarians can change their density in order to vary their depth. Large numbers of radiolarian skeletons litter the sea bed; these become fossilised to form minerals like flint. Magnification: x190 at 5x7cm size.