CHAPTER XV 

 PAIRING, COURTSHIP, AND PARENTAL CARE 



Intromittent organs: of Selachians, of Cyprinodonts. Breeding habits of 

 Cyprinodonts. Secondary sexual characters. Courtship of Fighting- 

 fish: of Dragonet, Pugnacity of males at breeding season. Parental 

 care: primitive nests. Nests of Mud-fishes, Bow-fins, Cat-fishes, etc. 

 Breeding habits of Three-spined Stickleback, of Fighting-fish and 

 Paradise-fish, of Bitterling. Cichlids and Cat-fishes carrying eggs in 

 the mouth and attached to the body. Care of eggs in marine fishes: 

 Lump-sucker, Gunnel, Kurtus. Egg-pouches in Pipe-fishes. Parasitic 

 males in oceanic Angler-fishes. 



Those fishes in which there is a definite courtship, or at least 

 a pairing of male and female during the breeding season, very 

 often show marked differences in the two sexes. These may 

 be of two kinds : ( i ) structural peculiarities directly concerned 

 with the fertilisation of the ova, generally taking the form of 

 special male organs for introducing the milt into the body of 

 the female; and (2) structural differences, peculiarities of 

 colour, etc., having no connection with sexual conjugation, 

 but concerned more with courtship and display, or with the 

 battles which take place between rival males. The so-called 

 "claspers " of a Shark are examples of the first type, the horny 

 tubercles on the snout of a Gyprinid at spawning time of the 

 second. 



In all Selachians the fertilisation of the ova takes place within 

 the female's body, and there is consequently a definite sexual 

 union. The mature males are provided with special organs, 

 the "claspers" or mixopterygia, appendages of the pelvic fins 

 (Fig. 107). Each has an internal cartilaginous skeleton, and 

 along the whole length runs a groove or canal leading from a 

 glandular sac at its base. During copulation the two grooves 

 or canals are placed close together, both the claspers are thrust 

 into the cloacal aperture of the female, and the seminal fluid 

 is introduced into the oviducts. In addition to the mixopterygia 

 which they possess in common with the Sharks and Rays, the 

 Chimaeras {Holocephali) are provided with other claspers: the 

 front portion of each pelvic fin is modified and separated off 

 to form an organ provided with two large dermal denticles, 



294 



