146 



COLLEGE ZOOLOGY 



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

 Fig. 93, B, ctr); 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 

 emerge from blind 

 pouches (Fig. 93, 

 A, 7), one on 



Fig. 93. — Ctenophora. A, Hormiphora plumosa. either side (Fi^. 

 Side view, I, mouth ; 2, aboral pole with sense organ; „, .... , 



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



6, canal; 7, tentacular pouch; 8, tentacle; 9, gelatin- exception the ten- 

 ous substance. B, Pleurobrachia pilcus, view of aboral . 



aspect, showing central statocyst, polar fields (Pf), tacles are not pro- 



and eight ciliated bands (ess, ctr). (A. from Shipley yided with Iiema- 

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



Treatise.) tocysts as are 



those of the 

 Ccelenterata, but are supplied with adhesive or glue cells called 

 colloblasts (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. 



■ctr. 



CSS. 



B 



