PHYLUM PROTOZOA. FLAGELLATES 



47 



of which one species {brevis) may occur in 

 such great numbers as to cause a periodic 

 red tide in coastal waters. The red tide may 

 appear anywhere in the world, in both 

 tropical and temperate waters. The mis- 

 nomer red tide is the popular name for the 

 brownish-amber discoloration of sea water 

 caused by this microscopic flagellate. Under 

 certain conditions it reproduces at a fantas- 

 tic rate; sixty million have been counted in 

 a single quart. 



The organism produces a toxic substance 

 that is fatal to fish. The tiny pest also re- 

 leases an airborne "poison gas" which ir- 

 ritates the human respiratory tract and may 

 cause coughing, sneezing, and even shortness 

 of breath. 



During the red tide off the coast of Florida 

 in 1952 and again in 1954 enormous num- 

 bers of fish died, and the shore was littered 

 for miles with stinking fish. An extensive red 

 tide results in the loss of tremendous 

 amounts of sea food. 



Another dinoflagellate, Gonyaulax, also 

 causes waters to appear a rusty red at times 

 because of its great numbers. Gonyaulax 

 catenella is known to have been the cause 

 of disastrous poisoning in man. Several kinds 

 of shellfish along the Pacific Coast feed on 

 them, thus making the shellfish poisonous 

 for human consumption. In 1941, there 

 were 346 cases of poisoning with 24 deaths. 

 Since 1941 state laws forbid the gathering 

 of shellfish during the season of the red 

 waters. Experiments have shown the toxin 

 to be about ten times as potent as strych- 

 nine, which is used for poisoning mice. 



The genus Mastigamoeba (Fig. 21) in- 

 cludes species that live in fresh water or in 

 the soil. They not only possess a flagellum, 

 but also form pseudopodia with which they 

 ingest food particles. 



Many flagellates are very complex in 

 structure, especially certain species that live 

 in the intestine of termites (white ants) 

 such as those shown in Fig. 447, p. 639. The 

 relations between these flagellates and the 

 termites in which they live are described in 

 Chapter 37. 



RELATIONS BETWEEN 

 SARCODINA AND MASTIGOPHORA 



Many zoologists believe that flagellates 

 evolved from the green algae among plants 

 and that the Sarcodina arose from a flagel- 

 late or flagellatelike organism. Many green 

 flagellates such as Volvox (Fig. 22) can 

 hardly be separated from green algae. A close 

 relation between amoebas and flagellates is 

 indicated by the fact that in certain species 

 both amoeboid and flagellate stages occur in 

 the same life cycle. Also certain types of 

 flagellates such as Mastigamoeba possess 

 both flagella and pseudopodia. Probably not 

 all Sarcodina arose from the flagellates; some 

 doubtless have evolved from other Sarco- 

 dina. 



CLASSIFICATION OF 

 THE MASTIGOPHORA 



{For reference purposes only) 



Class Mastigophora. These bear one or more 

 flagella in the adult stage. They may be amoe- 

 boid in shape but are generally covered with 

 a pellicle. Many of them are parasitic. Binary 

 fission is usually longitudinal division. No sex- 

 ual reproduction is known in many of the 

 genera. Two subclasses may be recognized ac- 

 cording to their principal method of nutrition. 

 The members of the subclass Phytomastigina 

 are mostly holophytic, although some are sa- 

 prozoic and may be in part holozoic. Those of 

 the subclass Zoomastigina are primarily holo- 

 zoic. 



Subclass 1. Phytomastigina (Or. phyton, 

 plant; mastix, whip). Plantlike; 

 chromatophores usually present; 

 often a red eye spot. 



Order 1. Chrysomonadina. Small; 1 or 2 

 flagella; some colonial. Ex. 

 Uroglenopsis americana (Fig. 

 39). 



Order 2. Cryptomonadina. One or 2 

 flagella and usually 1 or 2 chro- 

 matophores. Ex. Chilomonas 

 Paramecium (Fig. 21). 



