PARASITIC CRUSTACEA 



I I 



the female resembles a fat worm. The whole cycle from egg to the 

 death of the adult female takes about eight or ten weeks, and occurs 

 throughout the year, so that there may be half a dozen overlapping 

 generations in one year. The fish which are infected tend to linger 

 for a greater length of time in shallow water than their uninfected 

 fellows; this results in the nauplii being liberated in shallow water, 

 where they are more likely to encounter flounders. 



Fig. 49. Parasitic copepoda. A, Lernaeocera branchialis, adult 

 female from the gills of whiting (Gadus merlangus). Actual 

 length about 3 cm. B and C, Brachiella obesa, B, adult female, 

 Oblique view, actual length, excluding egg sacs, about 3 mm. C, 

 adult male, lateral view, drawn to same scale. Specimens taken 

 from the gills of red gurnard (Trigla cuculus). 



Lernaeocera branchialis is typically an inshore parasite. This is 

 in contrast with a very closely allied species, L. obtusa, which has 

 only very recently been recognised. The adult females of this species 

 are found on offshore populations of the haddock {Gadus aeglefinus), 

 and the chalimus stages are found on the lemon sole (Microstomia 

 kitt). There is also a difference in the site of attachment of these 

 two copepods : L. branchialis penetrates the junction of the heart 



