NOTES 
A Gastropod Parasite of Solitary Corals in Hawaii 1 
H. F. Bosch 2 
Of the species of wentletraps (marine gas 
tropods of the family Epitoniidae) that live 
with or feed upon anthozoan coelenterates, 
most are associated with sea anemones. Rob- 
ertson ( 1963 ) lists four species of these snails 
that are known to be either predators or ecto- 
parasites of sea anemones, as well as two oth- 
ers that are assumed to be so. A seventh wen- 
detrap, however, associates itself with a 
scleractinian, rather than with an actinian. 
Found attached to solitary corals of the genus 
Fungia in the Philippine Islands (Root, 1958), 
this wentletrap has been tentatively identified 
as Epitonium aff. costulatmn by Robertson, who 
considered it likely that the snail was feeding 
upon the coral. Thorson (1957) suggested that 
perhaps all members of the Epitoniidae were 
adapted for a parasitic mode of life. Evidence 
supporting both these 'ideas comes from a sim- ' 
ilar Epitonium-Fungia relationship recently 
noted in Hawaii. 
Specimens of the solitary coral, Fungia scu- 
taria Lamarck, collected in Kaneohe Bay, Oahu, 
during the summer and fall of 1963, occasion- 
ally had masses of small white eggs attached to 
them. Usually one or two fragile white snails 
also clung to the corals or to the egg masses. 
These snails were identified as Epitonium ulu 
Pi-lsbry, a wentletrap previously reported only 
from Hilo, Hawaii (Pilsbry, 1921:376; Ed- 
mondson, 1946:138). While only a small per- 
centage of the corals taken in the field had 
adherent eggs or snails, all corals kept in 
1 Contribution No. 221, Hawaii Marine Labratory. 
This study was in part supported by a National Science 
Foundation Summer Fellowship for Graduate Teach- 
ing Assistants. Manuscript received May 26, 1964. 
2 Present address : Department of Oceanography, 
The Johns Hopkins University, Baltimore, Maryland. 
aquaria eventually became infested with them 
during the course of several separate experi- 
ments carried out at the Hawaii Marine Lab- 
oratory. Thirty Fungia, in one instance, became 
infested within three weeks after having been 
placed in a large holding tank in order to test 
their ability to survive in an artificial environ- 
ment. These corals had been routinely inspected 
for damages due to collecting prior to being 
placed in the freshly cleaned tank, and seemed 
free of Epitonium eggs or adults. Yet each 
coral harbored from one to six snails, with 
attendant egg masses, at the end of the three 
week period. The increase in the snail popula- 
tion escaped notice during the interim as 
neither the snails nor their eggs ever appeared 
on the upper, feeding surface of the corals. 
Rather they restricted themselves to the un- 
tentacled areas of their host: the periphery or 
undersurface. By what means the snails were 
introduced into the tank is not known. Pos- 
sibly a few eggs had escaped notice when the 
corals were inspected, or larvae had entered 
with the sea water when the tank was initially 
filled. In either instance, it is clear that a num- 
ber of larvae had rapidly matured and had 
subsequently produced large clutches of new 
eggs. Although the sea water in the tank was 
not filtered or renewed during the three weeks, 
conditions seemed favorable for larval viability 
and growth, as many active veligers were prom- 
inent whenever egg masses were examined 
under the microscope. This seemingly rapid 
development of sexually mature wentletraps, 
the largest of which attained a length of 16.5 
mm, provides an index of maximal growth for 
Epitonium ulu. 
Tissue lesions on the undersurfaces of some 
of the corals (Fig. 1) may have been caused 
by Epitonium, but this was difficult to prove 
267 
