THE STICKLEBACK 



( Gastrosteus aculeatus] 



THE illustration given (Fig. 244) is the natural size of the three-spined 

 stickleback. There are said to be several kinds, but the above is 

 the one which is most plentiful all over Scotland. Every stream, 

 river, and ditch contains them, and they are also got in the sea all 

 round our coasts. They spawn in June, but before doing so a 

 rough nest is made, in which the female deposits her eggs. These 

 are hatched in from twenty-one to twenty-five days. While the eggs 

 are in the nest the male becomes very brilliantly coloured. His 

 belly is scarlet, his sides silvery, and his back yellow and green ; the 

 female, on the other hand, is usually of an olive green. He then 

 keeps a strict watch over nest and eggs, and allows no intruder to 

 come near. 



By December the young are about three-quarters of an inch long. 

 I have on many occasions kept them in a glass globe along with 

 minnows, but the sticklebacks always killed the latter. The usual 

 mode of attack was to swim close up to the minnow with fins spread 

 out and to dash at it sideways, using the hard spine in striking. 

 The minnow slipped out of reach for a moment, but the stickleback 

 renewed the attack in the same way three or four times, after which 

 the minnow fell lifeless to the bottom of the glass. The greatest 

 number of sticklebacks I have seen was at the outlet of Loch Leven. 

 Here they are drawn through the sluices, and being unable to re-enter 

 the loch, the water at this part literally swarms with them. 



If a new loch is made or an old one enlarged these interesting 



255 



