Mr. Heupel et Mb. Bennett, The occurrence, distribution and pathology associated with gnathiid isopodlarvae infecting the epaulette shark, Hemiscyllium ocellatum, INT J PARAS, 29(2), 1999, pp. 321-330
Gnathiid isopod praniza larvae were found to infect the epaulette shark Hem
iscyllium ocellatum. All sharks carried larvae on their external body surfa
ce, with the preferred attachment site in both sexes around the cloaca (P<0
.05). The claspers were the second site of preference in male sharks. Withi
n the buccal and branchial cavities, about 16% of larvae were attached to t
he roof and floor of the mouth and 84% attached to the gills. A significant
positive correlation existed between larval number and fish size. Histolog
ical examination showed that larval attachment in the buccal cavity elicite
d variable responses, the most severe being a loss of epithelium and compre
ssion of underlying tissue. No host cellular response or tissue proliferati
on was observed. Praniza attached preferentially to the efferent side of gi
ll filaments (relative to blood flow), and caused loss of epithelium, compr
ession of tissue, and a small amount of connective tissue proliferation. At
tachment to the gill septum or to the afferent side of the gill filament ca
used lamellar disruption, a cellular inflammatory response, and connective
tissue proliferation. Scanning electron microscopy showed little obvious pr
aniza-induced gill damage, other than localised tissue distortion to form "
pockets" around larvae attached between filaments. The results suggest that
praniza larvae do not cause sufficient tissue damage to adversely affect t
he health of this shark species. (C) 1999 Australian Society for Parasitolo
gy. Published by Elsevier Science Ltd. All rights reserved.