268 
PACIFIC SCIENCE, Vol. XIX, April 1965 
Fig. 1. The undersurface of the solitary coral Fungia scutaria Lamarck with the wentletrap Epitonium ulu 
Pilsbry and egg masses (arrows). The wentletrap is 1 6.5 mm long. White area to the right of the snail is a 
lesion in the coral’s tissue. 
inasmuch as the snails avoided the light. While 
no direct observations of wentletraps feeding 
on the corals were made, indirect evidence for 
this behavior was furnished by dissection. Vis- 
cera of snails taken from a coral invariably 
contained copious amounts of pink tissue in 
which were imbedded symbiotic algal cells 
( zooxanthellae ) and nematocysts, all charac- 
teristic of the corals. Moreover, wentletraps 
placed near corals which had been stained with 
a vital dye (neutral red) soon became suffused 
with the same color due to the ingestion of 
dyed coral tissue. (For such feeding to occur, 
it was necessary to keep the corals and the 
snails in the dark. ) 
Wentletraps in the absence of their egg 
masses were never found on Fungia. Thus the 
relationship between these two animals may 
be correlated with the breeding cycle of the 
snails and may be only intermittent or tempo- 
rary. The foregoing observations, however, 
show that Epitonium ulu is at least an occa- 
sional ectoparasite of Fungia scutaria. This evi- 
dence supports Thorson’s contention that the 
Epitoniidae in general are adapted to parasit- 
ism and also Robertson’s view of the parasitic 
nature of Epitonium aff. costulatum. 
ACKNOWLEDGMENTS 
I thank the various members of the Univer- 
sity of Hawaii faculty and of the B. P. Bishop 
Museum staff who have so kindly contributed 
helpful suggestions and criticism. I am particu- 
larly indebted to Dr. Alison Kay for identifying 
the specimens of Epitonium ulu as well as for 
her interest in this note. 
REFERENCES 
Edmondson, C. H. 1946. Reef and shore fauna 
of Hawaii. B. P. Bishop Museum Spec. Pub. 
22 : 138 . 
Pilsbry, H. A. 1921. The marine molluscs of 
Hawaii. Proc. Acad. Nat. Sci. Philadelphia 
72(3) : 3 7 6 . 
Robertson, R. 1963. Wentletraps (Epitonii- 
dae) feeding on sea anemones and corals. 
Proc. Malacological Soc. London 35(2 and 
3 ) : 51-63. 
Root, J. 1958. Rapa rapa in the Sulu Sea. Ha- 
waiian Shell News 7(1): 7-8. 
Thorson, G. 1957. Parasitism in the marine 
gastropod family Sealidae. Vidensk. Meddel. 
fra Dansk naturhist. Foren. 119:55-58. 
