THE IMPENETRABLE SEA 



many parts of their bodies. One squid, Vampyroteuthis 

 infernalis — one of the most sinister names given to any- 

 sea creature — has two near the base of its fins which 

 have eyehds or shutters which can be opened and closed. 

 Some squids have transparent windows through which 

 the hght from their photophores streams out. Other 

 squids have internal photophores, giving light within 

 their bodies. Others have photophores on eyeballs which 

 are on the ends of stalks — appliances which combine 

 range-finders with their searchlights. 



The fire-fly squid probably possesses the most efiicient 

 light-producing equipment of them all. Although a deep- 

 sea creature it comes to the surface to breed, each year 

 from April to June, in Toyama Bay in the Sea of Japan. 

 It is only four inches in diameter, but it has three fairly 

 large photophores on each of its arm-tips, and on two of 

 its arms numbers of photophores along their entire 

 length. It also has hundreds of photophores scattered 

 over its mantle. Thus equipped the fire-fly squid flashes 

 its lights periodically, as though it were signalling to 

 other creatures. The flashes vary in length and rapidity. 

 The arm, mantle and eye photophores can flash together 

 or separately — they give out the brightest light. The 

 photophores on the arm-tips can flash all together or 

 separately. Science remains in complete ignorance re- 

 garding the purpose of the lighting equipments of some 

 of these squids. 



The emission of light by living animals is a widespread 

 phenomena, which becomes limited to special parts of 

 the body in higher species. Many of the coelenterates 

 show tendencies towards such localization. In medusae 

 the whole body surface may be luminous, but the light 

 may be brighter along specific areas, such as the radial 

 canals, in the ovaries, or in the marginal sense-organs. 

 In certain polyps there are eight luminous bands. 



Creatures of the genus Pyrosoma are joined in free- 

 swimming colonies in the form of hollow Qylinders, closed 



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