Chapter 43 

 Class 2 Suctoria Claparede et Lachmann 



THE Suctoria which are also known as Acineta, Acinetaria, 

 TentacuHfera, etc., do not possess any ciha or any other cell- 

 organs of locomotion in the mature stage. The cilia are present 

 only on young individuals which are capable of free-swimming, 

 and lost with the development of a stalk or attaching disk, and 

 of tentacles. Therefore, an adult suctorian is incapable of active 

 movement. The body may be spheroidal, elliptical, or dendritic; 

 and is covered with a pellicle and occasionally possesses a lorica. 

 There is no cytostome, and the food-capturing is carried on ex- 

 clusively by the tentacles. Tentacles are of tw^o kinds: one is 

 suctorial in function and bears a rounded knob on the extremity 

 and the other is for piercing through the body of a prey and more 

 or less sharply pointed. The tentacles may be confined to limited 

 areas or may be distributed over the entire body surface. The 

 food organisms are usually small ciliates and nutrition thus is 

 holozoic. 



Asexual reproduction is by binary fission or by budding. The 

 buds which are formed by either exogenous or endogenous gem- 

 mation are ciliated, and swim around actively after leaving the 

 parent individual. Finally becoming attached to a suitable ob- 

 ject, the buds metamorphose into adult forms. Sexual reproduc- 

 tion is through fusion. 



The Suctoria live attached to animals, plants or non-living 

 matter submerged in fresh or salt water, although a few are para- 

 sitic. 



With only suctorial tentacles 

 Body irregular or branching 



Without proboscis or special arms; often with stolen; without 



stalk Family 1 Dendrosomidae (p. 629) 



With proboscis or special arms 



With retractile processes bearing tentacles 



Family 2 Ophryodeudridae (p. 632) 



With branched arms Family 3 Dendrocometidae (p. 632) 



Body more or less bilaterally symmetrical 



Exogenous budding and division 



Family 4 Podophryidae (p. 632) 



628 



