Sound Production in Triggerfishes — Salmon, Winn, and Sorgente 
17 
Fig. 4. Escape behavior of Rhinecanthus rectangulus when chased by a diver. Upper left : A fish circles 
toward the diver and then enters a hole in the reef ( upper right) . Below. Each photograph shows a fish which 
has entered a hole and locked its spines in place. The tails protrude from the holes. 
All fish stopped producing sounds a few sec- 
onds after attempts to dislodge them ceased. If 
pulled from the area, the fish continued to pro- 
duce sounds until released. These observations 
are based upon the behavior of over 60 R. rec- 
tangulus, and at least 15 fish in the remaining 
species (excluding B. cap i strut us ) . 
Most fish in the field were widely spaced, 
although in Melichthys sp. occasionally some 
were seen swimming in groups. In Batistes and 
Rhinecanthus, individual fish swam alone near 
the bottom, with only 5-10% of the fishes re- 
maining near a hole or ledge in the coral for 
brief periods (5-30 minutes). On one occa- 
sion, 17 B. hursa were seen feeding on a small 
area of coral. Several large fish briefly chased 
smaller conspecifics away from the area, then 
returned to feed. The chasing was accompanied 
by a slight opening of the mouth and rapid, 
continuous volleys of pectoral fin drumming 
sounds. In two other cases, quite different be- 
havior was observed during sound production. 
One fish approached another which had been 
hovering near a hole for several minutes. The 
"resident” and the "intruder” then slowly cir- 
cled, simultaneously rising about 1-2 m off the 
bottom. Brief volleys of pectoral fin sounds were 
produced by both fish as they circled. In addi- 
tion, the body coloration of both changed from 
the usual tan to a bright yellow. The intruding 
fish then swam away from the area. Brief chas- 
ing between conspecific R. rectangulus was also 
observed, but no sounds were detected. 
On two separate occasions, individual B. 
