Chapter Seven 



CTENOPHORA 

 (Comb Jelly-fish) 



Ctenophores are delicate creatures that re* 

 semble jelly-fish in general appearance but differ 

 from them in several details. They are practically 

 transparent and have rows of hair-like cilia which 

 appear in bands on the surface of the animal, giving 

 the appearance of the teeth of a comb. These cilia 

 propel the animal through the water. No stinging 

 cells (nematocysts) are present in this group. 



These ctenophores often occur in immense num- 

 bers and devour the microscopic life of the sea, in- 

 cluding the eggs and larvae of certain fish. 



Ctenophores are more abundant on the surface 

 of the sea at night. Many species are luminous and 

 are one of the causes of the "phosphorescence" often 

 seen on the sea at night. !) When rowing through 

 the water on August nights along the New Jersey 

 coast one often notices a flash of light every time 

 the oars strike the water. These flashes are pro- 

 duced by Mnemiopsis leidi. 



(!) Luminous microscopic protozoa (especially Noctiluca miliaris 

 Suri) also produce the so-called phosphorescence of the sea. 



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