THE SHAPING OF THE EGG STRINGS 

 IN THE COPEPODS 



By POUL HEEGAARD 



University of Indonesia 

 Bandung, Java 



When examining the different types of egg strings in the copepods, 

 the observer will be struck by the great variety of shape. Not only 

 does it vary among families, but also among closely related genera — 

 yes, even among different species of the same genus. For instance, 

 Brachiella ovalis (Kr.) has small, globular egg strings. The egg 

 strings of Brachiella merlucii Bassett-Smith are sausage-shaped ; 

 those of Brachiella trigla Claus and Brachiella rostrata Kroyer are 

 long, round bands, longer than the animal itself. This variation 

 within the same genus we fmd only in parasitic copepods. We have 

 egg-shaped egg strings in the Cyclopidae, round egg balls in the 

 Diaptomidae, and irregular egg clusters in many Harpacticidae, espe- 

 cially in the small forms living in the tidal zone and digging between 

 the sand grains in the upper i or 2 cm. of the beach. 



We find long strings with many eggs especially in parasitic copepods 

 living in the gill chambers of fishes, or egg strings curled in a spiral 

 held together by a mesenterial-like filament in many Lernaeidae, or 

 in a long, slender string with a single row of eggs in parasitic forms 

 attached on the surface of aquatic animals, as in Caligidae or in 

 Pennellidae. 



The shape of the egg strings is, of course, dependent on the num- 

 ber and size of the eggs in the egg string, but that does not give us 

 the whole explanation of their variety in shape. Nor, if we examine 

 the genital apparatus of the females, which has been minutely de- 

 scribed by Rathke, Claus, Scott, Wilson, and others, do we find an 

 explanation of this variation. There simply is no apparatus in con- 

 nection or contact with the genital duct to shape the egg strings. 

 The shape is entirely determined by the movements of the female and 

 the pressure of the water. This can be seen clearly when in the early 

 morning hours one observes the egg laying of one of the fish-parasite 

 copepod females. 



We will first look at a Caligus female with still empty egg strings 

 attached to her genital openings and the oviduct filled with ripe eggs 

 ready for fertilization and leaving the oviduct. The egg laying begins 



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