78 On the Habits and Food of the Stickleback. 



length ;* and leeches of the other species, when pretty well 

 grown, or longer than himself when expanded, were killed 

 in the manner above mentioned, but not swallowed. 



In one of his attempts to seize a leech, the stickleback, 

 having got it by the tail, the animal curled back, and fixed 

 its disc upon his snout. The efforts of the stickleback to 

 rid himself of this incumbrance were amusing. He let go 

 his hold of the leech, which then hung over his mouth, and 

 darting to the bottom and sides of the glass with all his 

 strength, endeavoured to rub off this tantalizing morsel. This 

 lasted for nearly a minute, when at last he got rid of the leech 

 by rubbing his back upon the bottom of the vessel. The leech, 

 perfectly aware of the company he was in, no sooner loosed 

 his hold, than he attempted to wriggle away from his devour- 

 er ; but before he had reached midway up the tumbler, the 

 stickleback had turned, and finished the contest by swallow- 

 ing him up. 



This voracious little fish not only preys upon the young of 

 the leech, but sometimes devours the fry of its own species. 

 In two or three instances, when leeches had not been procured, 

 a young stickleback, about half an inch long, was dropped in- 

 to the glass, and instantly swallowed. On other occasions, 

 when some of a larger size were put in along with him, he 

 contented himself with killing them. Perhaps the spines of 

 these larger fish, which are erected when in danger, and upon 



* It may be mentioned, as a curious instance of the wonderful arrange- 

 ments of Nature in securing the continuance of species, that the young of 

 the H. complanata, which I have generally found attached to aquatic 

 plants, were, in one instance which fell under my notice, affixed to the un- 

 der surface of the parent leech. This animal which, unlike most of its 

 congeners, never swims, had fastened itself to the side of the glass, and 

 three young ones, about a line in diameter, were thus exhibited to view 

 in a most interesting light for an animal so low in the scale of existence. 

 Thus protected, there was nothing to fear from the attacks of the stickle- 

 back or other enemies. They moved occasionally on the disc of the mo- 

 ther, and, it is conjectured, might remain in that situation, until they had 

 attained such a size as to render further care on the part of the parent 

 unnecessary. To convince myself that this protection was requisite, I de- 

 tached one with the point of a knife, which was instantly devoured by the 

 stickleback. The young H. complanata, from its transparency, forms a 

 beautiful object for the microscope. 



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