Other formats

    Adobe Portable Document Format file (facsimile images)   TEI XML file   ePub eBook file  

Connect

    mail icontwitter iconBlogspot iconrss icon

Studies on Gyrocotyle rugosa Diesing, 1850, A Cestodarian Parasite of the Elephant Fish, Callorhynchus milii

Eggs and Larvae of Gyrocotyle rugosa. (Figs. 3, 4)

page 4

Eggs and Larvae of Gyrocotyle rugosa. (Figs. 3, 4)

Eggs are fully embryonated in the rather short uterine sac and in the adjacent uterine coils. Such eggs, measured in alcohol mounts, are 122 to 135 microns (average 131 microns) long by 76 to 95 microns (average 80 microns) wide, thus being considerably larger than the eggs of G. urna or G. fimbriata. The egg shell is thin and colourless, the operculum inconspicuous. Most eggs show a small knob or boss at the anopercular end. No jelly was noted around the eggs and eggs did not tend to stick together.

Eggs removed by puncturing the terminal region of the uterus and placed in sea water immediately reveal very active embryos. The cilia beat vigorously and the embryo turns, twists, pushes, and struggles. Hatching occurs within a few minutes, apparently largely through the activity of the embryo. The lycophore larva swims very rapidly. It follows a spiral path but turns frequently. In a watch glass, the larvae swim to the top of the water every few seconds then turn and swim to the bottom. In addition, they speed in various directions as if searching for some host, as, indeed, they doubtless are. Since young larvae have been reported in the tissues of adult Gyrocotyle, a freshly collected adult was placed in a petri dish with large numbers of recently hatched larvae. No attraction toward the adult was noted and there was no evidence that any larvae adhered to or penetrated the worm. Reactions of the larvae to certain other objects will be discussed later.

Larvae were killed by pipetting into hot formal-alcohol-acetic solution. They were later stained with Delafield's hematoxlyn or with acetic alum carmine, and mounted in balsam.