Acoustical Behavior of the Menpachi, Myripristis herndti, 
in Hawaii 1 
Michael Salmon 2 
ABSTRACT : The menpachi ( Myripristis berndti) is found in aggregations inside 
caves and under ledges during the day in water more than 3 m deep. Diel tape 
recordings in these areas showed that the fish produced four types of sounds 
(knocks, growls, grunts, and staccatos), with no crepuscular peaks, from dawn to 
dusk. At night, when the fish scattered to feed, few sounds were detected. 
A fifth sound was produced when fish were hand-held. The sound-producing 
mechanism was determined by a series of ablation experiments on hand-held fish. 
It consisted of a pair of bilateral muscles attached to the skull anteriorly and the 
air bladder, the first two dorsal ribs, and the cleithrum bone posteriorly. 
Populations of 6-7 fish were maintained in the laboratory in large tanks with an 
artificial cave. They remained inside the cave during the day but swam actively 
throughout the tank at night. Brief chasing of a small fish by a larger, accompanied 
by knocking sounds, was frequently observed. Growl sounds were produced during 
more intense aggressive interactions between two fish of about the same size. There 
was no evidence of territoriality by members of any population. 
Few grunt or staccato sounds were produced when various species of nonpreda- 
tory fish were introduced among laboratory populations. Many of these sounds were 
elicited when moray eels were introduced. 
Sound playbacks to four populations from one of two speakers on either side 
of the cave elicited different responses depending on the sound tested. All fish 
immediately turned to and moved toward the experimental speaker when grunt or 
staccato sounds were played. Some fish briefly turned to the experimental speaker 
when knocks were emitted but none moved to the source. There was no detectable 
change in behavior when background noise was played back. 
Three fish tested in an aktograph showed increases in locomotory activity at 
night which corresponded with periods of nocturnal scattering and feeding in field 
populations. 
The acoustical system of the menpachi is compared with that of the longspine 
squirrelfish, Holocentrus rufus, an Atlantic species. 
The "Menpachi” consist of four species of 
economically important fishes in the Hawaiian 
area. Although their habits are well known to 
trap- and spearfishermen, there have been few 
published studies on their ecology and none on 
their acoustical behavior. In this report the be- 
havior correlated with or stimuli eliciting four 
types of sounds (grunts, staccato, knocks, and 
growls) produced by Myripristis berndti (Jor- 
dan and Evermann) are described. A fifth 
1 Contribution No. 267, Hawaii Institute of Marine 
Biology. Manuscript received March 7, 1966. 
2 Department of Biological Sciences, De Paul Uni- 
versity, Chicago, Illinois. 
sound, produced when fish were hand-held, ; 
was physically analyzed in conjunction with 
experiments to determine the sound-producing 
mechanism. Diel patterns of locomotory and 
feeding activity in nonreproductive groups of 
M. berndti , and their relationship to sound 
production were determined by field and lab- 
oratory observations. Experiments were carried 
out to determine the response of laboratory 
populations to playbacks of their own sounds 
and to other fish species commonly associated 
with them in their coral reef community. 
It has been known for many years that 
several species of squirrelfishes (family Holo- 
364 
