134 



KINGDOMS MONERA AND PROTISTA: 



Occurrence: with diatoms (Chrysophyta) consti- 

 tute the most typical and numerous life in fresh-water 

 and marine plankton; also include many parasites. 



Flagellates get their name from the possession of 

 one or more whip-like organelles, the flagellae, which 

 are locomotor and feeding structures. Many of these 

 protists possess chlorophyll and some of them even 

 have cell walls. For these reasons they are plant- 

 like. The chlorophyll allows the typical plant process 

 of photosynthesis. 



The flagellates are believed to approximate most 

 closely the ancestors of plants and animals. Within 

 the living flagellates one can find a transition from 

 cell-like to multicellular-like creatures. Also, there 

 is division of labor among a colony's "cells," a 

 feature of most multicellular animals (Eumetazoa) 

 whose individual cells, tissues, or organs have dif- 

 ferent functions. 



The flagellates are of major economic importance. 

 Certain of them cause diseases of man and animals, 

 perhaps the most serious human disorder being 

 African sleeping sickness. Termite-inhabiting flagel- 

 lates enable termites to obtain nutrients from wood 

 by performing the early stages of digestion. The "red 

 tides" that poison seafoods are fantastic concentra- 

 tions of certain flagellates. 



SARCODINA ( = RHIZOPODA) 



Diagnosis: characterized by flowing extensions of 

 the cytoplasm (pseudopodia) for locomotion (amoe- 

 boid movement) or feeding; worm-like movement, as 

 in some flagellates, is also found; individual's shape 

 irregular or spherical; simple to complex skeletons or 

 shells may be present; many bear flagellate young or, 

 in certain conditions, gain flagellae (hence cannot be 

 easily segregated from the flagellates); most are soli- 

 tary, mobile, and free-living creatures, but some are 

 colonial, sedentary, and/or parasitic (Figure 8.4). 



Structure: individuals regularly distinct, with a 

 cell membrane but without a cell wall; nucleus com- 

 plete and complex, one to many per individual but 

 none especially larger than the others; chlorophyll 

 absent; contractile vacuoles, one to several but with- 

 out contributing canals or vacuoles as in ciliates, are 

 found in fresh-water species; organization typically 

 less complex than that of the flagellates; no pellicle, 

 plastids, stigma, or trichocysts. 



Autrtlion: holozoic, saprophytic, or parasitic. 



SARCODINES 



Actmophrys 



Figure 8.4 Sorcodine types, all microscopic. 



Reproduction: mostly asexual by binary fission; 

 also asexual by multiple fission and plasmotomy 

 (cell division without mitosis that is somewhat 

 analagous to fragmentation; limited to multinucleate 

 species); sexual processes as in Flagellata. 



Occurrence: fresh-water, marine, and moist ter- 

 restrial habitats; many parasitic species are known. 



Sarcodina includes the amoeboid forms, those that 

 move and capture food by projecting their proto- 

 plasm in the direction traveled or toward prey. This 

 phylum is closely related to the flagellates — so close, 

 in fact, that some species are shifted between the 

 two phyla as various workers advance their interpret- 

 ations of life cycles. Both phyla show the alternation 

 of sexual and asexual generations. 



