Sound Production and Associated Behavior in Triggerfishes 1 
Michael Salmon 2 , Howard E. Winn 3 , and Nino Sorgente 2 
Two Atlantic and five Pacific species of 
triggerfish produce sounds by movements of 
the pectoral fins against the side of the body. 
The behavior associated with sound produc- 
tion was observed in the field and in popula- 
tions established in the laboratory. The sounds 
produced by all species when held by the hand 
underwater were analyzed and the pectoral fin- 
air bladder mechanism used to produce the 
sounds was studied principally by a series of 
ablation experiments. 
It has been known for many years that trig- 
gerfishes are capable of producing sounds (Spr- 
ensen, 1884; Mobius, 1889). At least three 
possible mechanisms of sound production have 
been suggested: stridulatory mechanisms, con- 
sisting either of movements of the front teeth 
against one another in Batistes carolinensis, B. 
capriscus, B. vetula, and Melichthys piceus 
(Fish, Kelsey, and Mowbray, 1952 ; Moulton, 
1958; Vincent, 1963) or of the first dorsal fin 
spine against underlying bones in B. erythrodon 
(Schneider, 1961) ; movements of the pectoral 
girdle bones against one another and the air 
bladder in B. aculeatus (Mobius, 1889) ; and 
"fluttering” or "drumming” of the pectoral fins 
against the side of the body in M. piceus, M. 
huniva, B. vetula, and B. carolinensis (S0ren- 
sen, 1884; Cunningham, 1910; Fish et ah, 
1952; Moulton, 1958). At the area of contact 
between the fin and body wall, the air bladder 
evaginated to form two bilateral lobes covered 
by a thin layer of integument and some en- 
1 Contribution No. 280, Hawaii Institute of Marine 
Biology. Part of the study was completed at the 
Lerner Marine Laboratory, Bimini, Bahamas, sup- 
ported by grants ONR 552(07) from the Office of 
Naval Research, and GB-3430 from the National 
Science Foundation. Work in Hawaii was supported 
by U.S. Public Health Service grant NB 06397 and 
a N.I.H. Postdoctoral Fellowship to the first author 
(1 F2 MH-18, 887-01). 
2 Department of Biological Sciences, De Paul 
University, Chicago, Illinois. 
3 Graduate School of Oceanography, University of 
Rhode Island, Kingston, Rhode Island. 
larged scales, called the "tympanum” by Gregory 
(1933). A better term, the "drumming mem- 
brane,” was used and illustrated by Moulton 
(1958). None of these proposed mechanisms 
of sound production have been verified experi- 
mentally. 
Sounds produced by tooth stridulation in 
triggerfishes have been recorded underwater 
in the laboratory, and from fish feeding in the 
field (Moulton, 1958). Sounds produced by 
pectoral fin movements have most commonly 
been elicited from specimens held in the air, 
although Moulton (personal communication) 
has since recorded them from specimens under- 
water. Schneider (1961) and Tavolga (1965) 
concluded that pectoral fin sounds were not 
normally produced by triggerfishes under nat- 
ural conditions in the field. 
As a result of the above studies, there is 
considerable confusion as to the nature and 
operation of sound -producing organs in trigger- 
fishes, as well as to the significance of the 
sounds themselves. This paper attempts to dem- 
onstrate that the pectoral fin-drumming mem- 
brane mechanism is used by several species, 
and that the sounds themselves are correlated 
with agonistic behavior in the field and the 
laboratory. 
MATERIALS AND METHODS 
Hawaiian triggerfish ( Rhine canthus rectan- 
gulus, Melichthys huniva, M. vidua , Batistes 
hursa, and B. capistratus ) were captured by 
hook and line, in fish traps, or by removing 
individuals from holes and ledges in the reef. 
All fish were captured from shallow waters 
(3-20 m) off the coast of Waikiki and Wai- 
anae, Oahu, from November to July, 1964-65. 
The fish ranged from 15 to 38 cm in total 
length. Individuals of the same species were 
hand-held underwater in fiberglas aquaria about 
7.5 cm from an Atlantic Research Corp. hydro- 
phone (LC-57) connected to a Uher 4000-S 
Report tape recorder. Tape speed during all 
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