136 



KINGDOMS MONERA AND PROTISTA: 



CILIATES 



Paramec ium 



Vorticella 



Figure 8.6 Ciliate types, all microscopic. 



Nutrition: mostly holozoic, some hunting their 

 prey and others creating currents that bring the 

 prey to them. 



Reproduction: asexual usually is by binary fission 

 in which resistant cysts are formed to endure un- 

 favorable environmental conditions; also probably 

 by budding; sexual reproduction usually involves a 

 unique process; life cycle perhaps mostly haplo- 

 biontic, adult diploid. 



Occurrence: abundant in the ocean and in fresh 

 water; some are parasitic; aquatic forms are among 

 the primary predators of the microscopic world. 



The ciliates are named for their hair-like locomotor 

 structures. Cilia are part of a coordinated locomotor 

 system composed of complex organelles. Many 

 ciliates are free-living forms that can be found in 

 almost any waters; others live in or upon other ani- 



mals. Most ciliates have both sexual and asexual 

 phases in their life cycles. 



Of particular interest in ciliates and suctorians is 

 conjugation, a reproductive process involving the 

 temporary coupling of two individuals. This process 

 occurs during meiosis and leads to cross- fertilization 

 by the exchange of nuclei that act as gametes. Con- 

 jugation is considered sexual reproduction although 

 there is no permanent fusion of cells. 



CLASS SUCTORIA (Suctorians) 



Diagnosis: young resemble ciliates; adults spheri- 

 cal, oval, inverted conical or branched protozoans 

 fastened either by a stalk or directly to living or 

 nonliving aquatic objects; adults with food-getting 

 tentacles that either cover the body or are concen- 

 trated at the unattached end of the body and are or- 

 ganized into two or three clusters (Figure 8.7). 



Structure: much as in ciliates, except for lacking 

 cilia and most organelles in the adults; organelles 

 that are present include contractile vacuoles; one 

 large plus many small nuclei. 



Nutrition: holozoic; tentacles capture and paralyze 

 prey which is sucked into the body through tentacular 

 canals. 



A SUCTORIAN 



Acineta 



Figure 8.7 A suctorian, microscopic. 



