140 



MARINE AQUARIA 



respond by slight movements. Care on this point is of vital importance, 

 as decomposition is very rapid. 



Sea Horses. Owing to the vastness of the field we cannot here go 

 into a detailed list of marine aquarium inhabitants, but we cannot pass 

 the subject without special mention of those quaint fishes, sea horses 

 {Hippocampus) . Although appearing like some mythological animal in 

 miniature, they are true fishes. They make a very striking appearance in 

 the aquarium, always attracting great attention. Their tails are prehen- 

 sile and are used much the same as a monkey's, fastening themselves to 

 twigs, bits of grass or any small object, ready to let go in a moment, 

 swim a short distance and fasten somewhere else or perchance socially 

 link tails with another. Their movements through the water might be 

 described as being very sedate. Locomotion is produced mainly by vibra- 

 tion of the dorsal fin, the body being tipped forward at a slight angle. 



Although the movement through the water 

 is not rapid, it has the appearance of being 

 accomplished entirely without effort. The 

 breeding habits of the sea horse are also most 

 peculiar. The female develops an intromit- 

 tent organ as the breeding season approaches, 

 while the brood-pouch on the belly of the 

 male becomes thickened and vascular. The 

 fishes face each other, the female advances, 

 places one or more eggs in the pouch of the 

 male, retreats and repeats until the spawning 

 is finished. When the eggs have hatched, the 

 pouch splits slightly and he works the young 

 out of it by gently rubbing against a firm sur- 

 face. The young are as perfectly formed as 

 the parents. 



Sea horses feed upon small marine Crus- 

 tacea about equal in size to daphnia. Some 

 European aquarists claim to have gotten them 

 to eat dried shrimp, but, so far as we are able to learn, nobody in America 

 has been successful in this. Although different attempts were made to 

 induce them to eat daphnia, it has seldom been accomplished. The 

 author was fortunate enough to persuade sea horses to modify their ideas 

 to that extent, the process taking much patience. Daphnia can only live 

 about 5 minutes in seawater, so at first they all die while the sea horses 

 are apparently thinking the matter over. By repeated trials the smaller 

 fishes finally started to eat, and the larger ones took the hint from the 

 smaller. Shrimp will eat the dead daphnia, but if much is left over it 



Fig. 113. Sea Horse 

 (Maximum size) 



