Class Polycystinea.

ANDERSON O. R; NIGRINI CATHERINE; BOLTOVSKOY DEMETRIO; TAKAHASHI, KOZO; SWANBERG NEIL

“An Illustrated Guide to the Protozoa", Second Edition

Society of Protozoologists

Lugar: Kansas; Año: 2002; p. 994 - 1022

The polycystines are solitary or colonial, actinopod-bearing, marine, planktonic protists falling into two main groups: 1. Spumellaria with a spherical, cell body plan (Figs. 1 & 2), though the skeletons may have very different symmetries, and 2. Nassellaria with a non-spherical cell body plan and skeletons varying from simple spicules to complex helmet-shaped structures (Figs. 3 & 4). Sizes vary from about 30 m to several hundred m for many skeletal-bearing species, or to several millimeters for larger gelatinous spumellarian species. Most known species occur in open-ocean environments, but some occur in coastal waters. Radiolarian siliceous skeletons contribute substantially to the microfossil record in marine sediments providing one of the most continuous records of micro-organismic evolution (e.g., Kling 1978, Riedel and Sanfilippo 1985, Sanfilippo, Westberg-Smith and Riedel 1985) extending back to the Cambrian, while many modern species can be clearly traced back at least to the early Mesozoic (e.g., Anderson 1983a).