502 



PARENTAL CARE AMONG FRESH-WATER FISHES. 



selected localities, a nest was found in each, composed of a collection of deli- 

 cate vegetable fibers, resting on the bottom of the trough and matted into an 

 irregularly circular mass, somewhat depressed, and upward of an inch in 

 diameter, the top being covered over with the same materials and having in the 

 center a large hole. The fishes scarcely ever strayed from their nests, but were 

 constantly on guard, defending or repairing them. They were perpetually 

 prying into the hole- at the top and thrusting their heads right into it. On 

 one occasion, one of them entered l)y this hole, and slowly forced itself through 

 the side of the nest. As it gradually moved onwards its body had a pecu- 

 liar, lateral vibratile motion. 

 They would frequently seize 

 hold of the nest and give it a 

 violent tug, shaking :ind 

 tearing loose the vegetable 

 matter of which it was 

 composed ; at other times 

 they would carry to it in 

 their mouths fine conferva- 

 stems and press them witli 

 considerable force into the 

 wall of the nest or thrust 

 them into the hole, which 

 by this means was par- 

 tially concealed. Occasion- 

 ally each was observed hover- 

 ing over its nest with the 

 head close to the orifice, the 

 body being inclined upwards 

 at an angle of about 45°, 

 fanning it with the pectoral 

 fins, aided by a lateral mo- 

 tion of the tail. This curious 

 nuuKeuvre was apparently 

 for the purpose, so to speak, 

 of ventilating the spawn, 

 which could be distinctly 

 seen through the orifice at 

 the top ; at least, by this 

 means, a current of water 

 was made to set in towards 

 the nest, as was rendered 

 perfectly evident by the agi- 

 tation of particles of matter 

 attached to it. This fanning or ventilating process was repeated at short 

 intervals during the day and every day until the s]iawn was hatched, to 

 accomplisli which took between two and three weeks. 



Only one nest contained spawn ; the other was torn in pieces and the mate- 

 rials scattered about, in the hope that we might have the pleasure of seeing it 

 reconstructed. In this we were not disappointed : the fish immediately began 

 to form a new nest in exactly the same spot, and by the following day it was 

 more than half completed. It took a mouthful at a time and was at some 

 pains in adjusting each load, spreading the materials out and pressing them 

 down with its mouth ; it then drew its body slowly over the whole, vibrating 



/ 



Fig. 85. — Three-spined Stickleback male assisting female in 

 spawning. After Coste. 



