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

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

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.