Geographic and vertical distribution patterns of living Radiolaria are closely related to the characters of the water column. We studied living Radiolaria in samples collected at closely spaced depth intervals in the waters surrounding Japan in order

Hand separated radiolarian skeletons, mainly from the Panama Basin PARFLUX sediment trap (5°21.8′N, 82°01.4′W) samples, were measured for length, width, and projected area (58 species), and weight (53 species). Volume and density contrast were computed.

Polycystina (~400–800 living species and several thousand extinct forms) and Phaeodaria (~400–500 living species) are exclusively marine, open-ocean planktonic protists, most of which possess elaborate siliceous skeletons. The cytoplasm is divided into

Fluxes of living radiolarians collected in particle traps in the North Pacific central gyre ranged from 5.4 × 104 m−2 at 50 m (of which 52% resulted from individuals of colonial radiolarians) to 103 m−2 day−1 at 2000 m. The fluxex of total radiolarians