BONY FISHES 279 



also explains why this fish frequents by preference waters which are 

 richly provided with plants. Here, however, it finds also an abundance 

 of animal food, for an exuberant plant life always carries a rich animal 

 life in its train (give proofs). A further sine qua non in the selection of 

 its habitat is the presence of deep portions which 

 do not freeze over, and in which the fish can 

 hibernate. 



C. Enemies. 



From the egg down to its death this peaceful 

 fish is encompassed by dangers. Otters, rats, 

 water- shrews, sea-eagles, herons, and many other 

 aquatic birds, as well as predaceous fish, inces- 

 santly pursue it. Its smaller-sized enemies have 

 to content themselves with young fish, but the 

 larger and stronger of its foes can overpower fish weighing many pounds. 

 (The carp attains to a good age, and a weight of above 66 pounds. The 

 so-called "grey-beards" among the carp are very old fish, the bodies of 

 which are covered with a parasitic growth of algae or fungi. How are 

 such growths correlated with the slow and lazy habits of the fish ?) 

 The carp is a defenceless animal, being utterly unequipped with weapons 

 of defence (proof). 



(a) The dorsal and anal fin carry each in front a sharp, toothed 

 spine ; this, however, cannot be rigidly erected (see stickleback), and 

 hence is of no importance as a defensive weapon. 



(b) As in the majority of fish, in the carp also the upper side of the 

 body is of a far darker colour than the under surface. Hence, when 

 viewed from above (by enemies in the air and the upper strata of the 

 water) the fish cannot easily be distinguished from the dark bottom, and 

 seen from below (by enemies at the bottom and in the lower strata of the 

 water) presents but a slight contrast against the bright sky. Neverthe- 

 less, this double coloration (back blackish-grey to blackish-brown, sides 

 and belly mostly yellowish) affords it but slight protection against its 

 keen-sighted enemies. A more effectual means for the preservation of 

 its species rests upon its great 



D. Fecundity. 



According to calculations, a large female deposits as many as 

 700,000 eggs at one spawning. (Explain the importance of this strong 

 reproductive power in the artificial culture of this fish.) 



