The Luminescence of Some Deep-sea Fishes of the Families Gadidae 
and Macrouridae 
Yata Hanedai 
INTRODUCTION 
While studying the Japanese fish Fhysi- 
culus japonicum Hilgendorf, of the family 
Gadidae, Franz (1910) noticed a round black 
pigmented spot situated ventrally and in 
front of the anus. He studied its structure, but 
was unable to explain its physiological func- 
tion. 
Later Kishitani (1930) examined this organ 
and discovered it was an open type of lumi- 
nous organ containing symbiotic luminous 
bacteria. He described its structure and gave 
a specific name to the bacterium, Micrococcus 
physiculus. He could not see any luminosity 
while the fish was living under natural con- 
ditions, and concluded that the luminous 
organ merely produced luminous bacteria 
which were ejected occasionally as a lumi- 
nous cloud into the surrounding sea water. 
In August, 1936, I had an opportunity to 
observe this fish in the dark in an aquarium 
tank at the Asamushi Marine Biological 
Station of Tohoku University, Among many 
other fishes in the tank, I saw one which I 
had never seen before, which emitted light 
from this ventral spot. It did not eject a 
luminous cloud of matter. 
In August, 1937, 1 observed another species 
of the Gadidae, Lotella phycis Temm. & Schl., 
which also possessed a similar type of lumi- 
nous organ, from the duct of which I was able 
to culture luminous bacteria in artificial 
media. 
The fishes of the family Macrouridae are 
closely related to the Gadidae and have a 
luminous organ of the same type. Their 
^ Tokyo Jikeikai Medical College, Tokyo, Japan. 
Manuscript received January 26, 1949. 
luminosity was first recorded by Osorio 
(1912). One species of the family, Malaco- 
cephalus laevis (Lowe), has the same type of 
luminous organ, similarly situated. Osorio 
stated that it was a practice of the Portuguese 
fishermen to force luminous matter from the 
organ by pressing it against pieces of shark 
flesh which they used as bait. In this way the 
flesh became luminous, and so was improved 
as bait for their fishing. This led him to be- 
lieve that the luminous matter consisted of 
luminous bacteria, but since he was unable 
to culture any he could not confirm his belief. 
Hickling (1925, 1926) described the struc- 
ture of the luminous organ of this fish, and 
stated that it was of a new type, the luminous 
matter in the organ consisting of luminous 
granules. In 1931 the same author described 
the luminous gland of Coelorhynchus coelorhyn- 
chus Risso, also as a new type of luminous 
organ containing a luminous granular sub- 
stance. 
Yasaki and Haneda (1936) reported that 
there were 10 species of the Macrouridae with 
luminous organs, from the ducts of which 
they cultured luminous bacteria in artificial 
media. 
In 1938 I examined Malacocephalus laevis, 
described its luminous organ and the con- 
tents, and cultivated luminous bacteria from 
it. Imai (1942) made bacteriological examina- 
tions of material from five species of the 
Macrouridae. 
Recently Parr (1946) has studied many 
macrourid fishes of the western North At- 
lantic and the Central American seas. He 
recognized the outer aspect of the luminous 
organs on the ventral regions of fishes of the 
genera Hymenocephalus, Malacocephalus, Ven- 
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