Pelagic Environment 



151 



Catastrophic death of fishes off Florida has 

 also been attributed to blooms of dinoflagel- 

 lates (Gunter, William, Davis, and Smith, 

 1 948) by either poisoning or suffocation. 



Two other kinds of phytoplankton that 

 have fiagella are coccoliths and silicoflagel- 

 lates. Although rare, the chief genera of 

 the first are Coccosphaera and Rhabdosphaera. 

 Both are calcareous and so small that they 

 generally pass between the meshes of 

 plankton nets , yet they are reported to com- 

 prise as much as 13 per cent of some deep- 

 sea sediments (Correns, 1939). Recent 

 studies by M. N. Bramlette (1958) have 

 shown that coccoliths can be useful guide 

 fossils in the geological column. Silicoflagel- 

 lates also are rare off southern California, 



only Dictocha fibula having been recognized 

 in studies at University of Southern Cah- 

 fornia during 1955-1956, although Butschh 

 (1880-1882) reported many others elsewhere. 

 Their siliceous skeletal remains are preserved 

 in the sediments, but their small size makes 

 for difficulty in finding them. 



Other planktonic organisms are definitely 

 animal in origin. Some are protozoans, 

 radiolarians, foraminiferans, and tintinnids. 

 The tiny radiolarians with their siliceous 

 skeletons contribute appreciably to some 

 deep-sea sediments but are unimportant off 

 southern California. Tintinnids are fairly 

 common in the region (Kofoi'd and Grin- 

 nell, 1929) but have few or no hard parts. 

 Most abundant of the three are forami- 



Figure 132. Common net 

 plankton off southern Califor- 

 nia. Diatoms (X 100 to x250), 

 from Cupp (1943): A, Coscino- 

 sira polychorda Gran.; B, Lep- 

 tocylindrus danicus CI.; C, 

 Rhizosolenia alata Brightw.; 

 D, Nitzschia pungens var. at- 

 lantica CL; E, Chaetoceros de- 

 cipiens CI.; F, Ditylum bright- 

 wellii (West) Grun. 



Coccolithophorid (x300): 

 G, Coccosphaera pelagica Wall., 

 silicoflagellate (x50); H, Dic- 

 tyocha fibula Ehrbg. 



Dinoflagellates (XlOO to 

 X200), from Butschli (1883- 

 1887): I, Goniaulax polyhedra 

 Stein; J, Porocentrum micans 

 Ehrbg.; K, Ceratium fusus 

 Ehrbg. 



Tintinnids ( x 60), from Ko- 

 foid and Grinnell (1929): L, 

 Favella franciscana K & G.; 

 M, Heliocostomella subulata 

 (Ehrbg.). 



Radiolarian (rare) (xlVO), 

 from Sverdrup, Johnson, and 

 Fleming (1942): N, unknown 

 species. 



Foraminifer (x25); O, Glo- 

 bigerina bulloides d'Orbigny. 



