HATCHING PATTERNS OF THE MONOGENEAN PARASITES BENEDENIA-SERIOLAE AND HETERAXINE-HETEROCERCA FROM THE SKIN AND GILLS, RESPECTIVELY, OF THE SAME HOST FISH, SERIOLA-QUINQUERADIATA

Eggs of the capsalid monogenean skin parasite Benedenia seriolae and the polyopisthocotylean gill parasite Heteraxine heterocerca, from the same host, the yellowtail Seriola quinqueradiata, have strikingly different hatching patterns when incubated under identical environmental conditions with natural illumination and constant temperature. B. seriolae eggs hatch throughout the hours of daylight, with an indication of an early and a tate hatching peak during the day, while H. heterocerca has a strong hatching peak at dusk and emergence declines in frequency during the night. The significance of this difference in hatching pattern is discussed.