18 THE SEA SHORE 



This is often a matter of no little importance to the sea-side 

 naturalist, who may require to keep marine animals alive for some 

 time at considerable distance from the sea shore, while their growth 

 and habits are observed. Hence we shall refer to this subject again 

 when dealing with the management of the salt-water aquarium. 



The attractions of the sea coast are undoubtedly greater by day 

 than at night, especially in the summer season, when the excessive 

 heat of the land is tempered by the cool sea breezes, and when 

 life, both on the cliffs and among the rocks, is at its maximum. 

 But the sea is grand at night, when its gentle ripples flicker in the 

 silvery light of the full moon. No phenomenon of the sea, however, 

 is more interesting than the beautiful phosphorescence to be 

 observed on a dark summer's night. At times the breaking ripples 

 flash with a soft bluish light, and the water in the wake of a boat 

 is illuminated by what appears to be liquid fire. The advancing 

 ripples, as they embrace a standing rock, surround it with a ring of 

 flame ; while streaks and flashes alternately appear and disappear 

 in the open water where there is apparently no disturbance of any 

 kind. 



These effects are all produced by the agency of certain marine 

 animals, some of which display a phosphorescent light over the 

 whole surface of their bodies, while in others the light-giving 

 power is restricted to certain organs or to certain well-defined areas 

 of the body ; and in some cases it even appears as if the creatures 

 concerned have the power of ejecting from their bodies a phos- 

 phorescent fluid. 



It was once supposed that the phosphorescence of the sea was 

 produced by only a few of the lower forms of life, but it is well 

 known now that quite a large number of animals, belonging to 

 widely different classes, play a part in this phenomenon. Many of 

 these are minute creatures, hardly to be seen without the aid of 

 some magnifying power, while others are of considerable size. 



Among the peculiar features of the phosphorescence of the sea 

 are the suddenness with which it sometimes appears and disappears, 

 and its very irregular variations both at different seasons and at 

 different hours of the same night. On certain nights the sea is 

 apparently full of living fire when, almost suddenly the light 

 vanishes and hardly a trace of phosphorescence remains ; while, on 

 other occasions, the phenomenon is observed only on certain patches 

 of water, the areas of which are so well defined that one passes 

 suddenly from or iiito a luininoxis sea. 



