Chap. 21 



THE PROTOZOANS 



435 



Ponds, lakes, 

 and seas 



DINOFLAGELLATES 



2. 



Red tides, 

 Florida 



Red waters, 

 Pacific Coast 



Living light, 

 all oceans 



Fig. 21.8. Dinoflagellates: armored and unarmored types. /, Ceratium, with the 

 typical armorlike shell and flagellum. 2, a dinoflagellate (Gymnodinium) that 

 often sheds its armor and becomes a naked swimmer. They occur in vast numbers 

 in the "red tides" of Florida. Tons of dead fishes are thrown on the beaches when- 

 ever these protozoans abound. 3, Gonyaulax polyhedra, a main cause of some of 

 the red water of the oceans. Several kinds of shellfishes feed on them after which 

 they are poisonous as human food. 4, Noctiluca, a relatively large translucent 

 sphere. They float on the sea in vast numbers, each one flashing light. Together 

 they create miles of bioluminescence. //, tentacle; //, flagellum; tf, flagellum; s, 

 groove. (Courtesy, Jahn and Jahn: The Protozoa. Dubuque, Iowa, Wm. C. Brown 

 and Co., 1949.) 





Colony of collared cells Each cell o food frop 



> 3. 



Proterospongia, collored cells 



unique in protozoans 



and sponges 



Fig. 21.9. Protozoans that suggest sponges. /. Codosiga botrytris, each individual 

 of the colony has a kind of food trap called a collar cell or choanocyte. 2, four 

 cells of the colony in different stages of catching and ingesting food; A, a particle 

 caught by the flagellum is whipped against the collar which contracts; B, slides 

 the particle against the body of the cell; C and D, finally it enters the cell body. 

 3, Proterospongia, so called because of the resemblance of its cells to the collared 

 cells (choanocytes) of sponges. (Courtesy, Jahn and Jahn: The Protozoa. Du- 

 buque, Iowa, Wm. C. Brown and Co., 1949.) 



