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PACIFIC SCIENCE, Vol. XII, October, 1958 
into this more complex symbiotic association. 
In Papetoai Bay, Moorea, at a depth of 20 
feet, about a 200 mm. Parupeneus trifasciatus 
(Lacepede) approached an adult L. dimidiatus . 
As it neared the latter, it changed its color 
rapidly from light tan to mottled pink. The 
Labroides picked over the body and fins of 
this goatfish, moving anteriorly. When it 
reached the forward part of the head, the 
goatfish opened its mouth and the wrasse in- 
serted more than half of its body into the 
mouth and remained there several seconds. 
Subsequently two adult goatfish of the spe- 
cies Mulloidichthys samoensis (Gunther) inter- 
rupted the pair and received the attention of 
the Labroides. D. W. Strasburg has written 
that he made the same observation with L. 
dimidiatus and P. trifasciatus at Eniwetok Atoll 
in the Marshall Islands. In Teavenui Pass, 
Bora Bora, Society Islands, at a depth of 
about seven feet, I saw a 1240 mm. moray eel 
(Gymnothorax javanicus Bleeker) with its head 
and anterior third of its body projecting from 
beneath a coral ledge. It was being picked 
over by a L. dimidiatus about 50 mm. long. 
After about 30 seconds the wrasse devoted its 
attention to the eel’s head, whereupon the 
latter opened its mouth widely, maintaining 
it in this position for about eight seconds 
while the labrid picked inside the upper and 
lower jaws and then disappeared back into 
the pharynx. A sharp lateral jerk of the eel’s 
head preceded the departure of the wrasse. 
The eel was then speared to permit positive 
identification. A similar observation was made 
at Takaroa in the Tuamotus. The eel ap- 
peared to be the same species and the L. 
dimidiatus was a juvenile about 20 mm. in 
length. At Caroline Atoll (10° S., 150°14' W.) 
I saw an adult L. dimidiatus slip the anterior 
third of its body into the gill cavity of the 
chaetodontid Hemitaurichthys thompsoni Fowler 
by way of the gill opening. The latter held its 
opercula open without respiring for several 
seconds to accommodate the labrid. In the 
Tuamotus individual L. dimidiatus were ob- 
served to enter the gill cavities of the wrasse 
Epibulis insidiator (Pallas), the grouper Variola 
louti (Forskal), and the goatfish Parupeneus 
barberinus (Lacepede) via the gill openings. 
Labroides dimidiatus are frequently seen in 
pairs. Also it has been noted that individual 
fish or pairs of fish appear to remain around 
the same small coral head or small section of 
a larger reef. The fish described above in as- 
sociation with Parupeneus trifasciatus is one of 
a pair which has been sighted in the same 
area over a period of six months. Other pairs 
or individual fish have been observed to be 
restricted to small areas. 
If a parasite-feeding fish is resident to a 
small section of bottom and other fishes in 
the area are nonmigratory (probably true for 
the majority of coral reef fishes), its food sup- 
ply would be insufficient, for it would be 
limited to the ectoparasites of fishes in its im- 
mediate surroundings. Therefore, it was not 
surprising to note that fishes come from be- 
yond the range of vision to a Labroides site. A 
school of subadult Mulloidichthys samoensis 
was consistently seen to occupy a region of 
sandy bottom over 50 feet from the shore 
reef where the pair of L. dimidiatus mentioned 
above could be found. As I watched, small 
groups of about eight of the goatfish moved 
toward the Labroides site and remained in the 
area until they had been picked over; then 
they would return to their usual place. Their 
swimming back and forth from where the 
school congregated to where the Labroides 
were resident was not haphazard but direc- 
tional, even though the water was not clear 
enough for me to see the reef from where the 
school was situated. Another species which 
swam to these two labrids from a locality 
previously known to me was a large adult 
Abudefduf septemfasciatus (Cuvier and Valen- 
ciennes), the only one of its size in the area. 
The rocks along the shore where it habitually 
hid are 45 feet from the labrid locale. Caranx 
melampygus Cuvier and Valenciennes, a foot 
or more in length, were other visitors which 
came to be "serviced” and left when the 
service had been finished. These fish are what 
