Chapter 44 

 Class 2 Suctoria Claparede and Lachmann 



THE Suctoria which have been also known as Acinetaria, 

 Tentaculifera, etc., do not possess any cilia 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 exclusively by the tentacles. 

 Tentacles are of two 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 is thus holozoic. 



Asexual reproduction is by binary fission or by budding. The buds 

 which are formed by either exogenous or endogenous gemmation are 

 ciliated, and swim around actively after leaving the parent individ- 

 ual. Finally becoming attached to a suitable object, the buds meta- 

 morphose into adult forms. Sexual reproduction is through a com- 

 plete fusion cf ccnjugants. 



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

 submerged in fresh or salt water, although a few are parasitic. 



With only suctorial tentacles 

 Body irregular or branching 



Without proboscis or special arms; sometimes with stolon; without 



stalk Family 1 Dendrosomidae (p. 696) 



With proboscis or special arms 



With rectractile processes bearing tentacles 



Family 2 Ophryodendridae (p. 698) 



With branched arms Family 3 Dendrocometidae (p. 699) 



Body more or less bilaterally symmetrical 



Exogenous budding and division. .Family 4 Podophryidae (p. 699) 

 Endogenous budding 



Pellicle thin; within or without lorica; with or without stalk. . . . 



Family 5 Acinetidae (p. 700) 



Pellicle thick; without lorica; a few tentacles, variable in form; 



stalk short, stout Family 6 Discophryidae (p. 706) 



With suctorial and prehensile tentacles; with or witho t lorica; ex- 

 ogenous budding; commensals on marine hydroids 



Family 7 Ephelotidae (p. 709) 



695 



