146 



COLLEGE ZOOLOGY 



the aboral end are eight meridional ciliated bands (Fig. 93, A, 5; 

 Fig. 93, B, ctr)j these are the locomotor organs. Each band has 

 the cilia arranged upon it in transverse rows and fused at the 

 base; each row thus resembles a comb. These are raised and 

 lowered alternately, starting at the aboral end, and cause an 

 appearance like a series of waves travel- 

 ing from this point toward the mouth. 

 The animal is propelled through the 

 water with the oral end forward. Light 

 is refracted from these moving rows of 

 cilia, and brilliant, changing colors are 

 thus produced. 

 Some species are 

 phosphorescent. 

 Most cteno- 

 phores possess 

 two solid ] contrac- 

 tile tentacles (Fig. 

 93, A, 8) which 



p f'~" ^^4 *\<&? emerge from blind 



.pouches (Fig. 93, 

 A, 7), one on 

 either side (Fig. 

 With one 

 exception, the ten- 

 tacles are not pro- 

 vided with nema- 

 tocysts as are 

 those of the 



CCELENTERATA, but are supplied with adhesive or due cells called 

 cnUobla^ts (Fig. 95). The colloblasts produce a secretion of use 

 in capturing small animals which serve as food. The spiral 

 filament (sf) in each colloblast is contractile, and acts as a 

 spring, often preventing the struggling prey from tearing the 

 cell away. 



c.ss. 



FIG. 93. CTENOPHORA. A, Hormiphora plutnosa. 

 Side view, i, mouth ; 2, aboral pole with sense organ; 

 3, funnel; 4, paragastric canal ; 5, a ciliated band; -93 > -"/ 

 6, canal; 7, tentacular pouchj 8, tentacle; Q, gelatin- 

 ous substance. B, Pleurobrachia pileus, view of aboral 

 aspect, showing central statocyst, polar fields- (Pf), 

 and eight ciliated bands (c.ss, c.tr). (A, from Shipley 

 and MacBride, after Chun ; B, from Lankester's 

 Treatise.) 



