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PACIFIC SCIENCE, Vol. XXI, April 1967 
navy blue often appears as velvety black. 
Separating these contrasting colors are three 
lengthwise stripes along the sides. The upper 
stripe is narrow and light blue, the middle is 
broad and black, and the lower is narrow and 
silvery white. The light-blue stripe commences 
on the upper snout (where it meets its fellow), 
touches the upper edge of the eye, and con- 
tinues thence to the caudal base. The black 
stripe runs from the snout through the eye 
to the caudal base, and expands on the caudal 
fin so that the fin is black except for narrow 
white dorsal and ventral margins. The silvery- 
white stripe runs from the rictus to the 
lower edge of the eye and thence along the 
lower mid-side to the caudal base. The dorsal 
and anal fins are black basally and margined 
with white anteriorly. The pectorals and pelvics 
are plain blackish. 
This color was characteristic of the captive 
lousefish during its first 7 days in the swimming 
pool. Thenceforth its ventral surface gradually 
darkened, changing from white to gray-spotted 
(eighth day) to uniform gray (ninth day) to 
gray-black (tenth day). Subsequently the color 
of its undersides fluctuated between gray, deep 
slate blue, and black, there being no apparent 
relation between color and incident light or 
fish activity. Frequently, however, the color of 
the undersides was lighter just after feeding. 
Sometimes the back and the base of the dorsal 
and anal fins were the same color as the under- 
sides. The three lateral stripes were unvaryingly 
the same. By the twenty-first day the fish’s 
dorsal and ventral surfaces were both jet black, 
and no further changes were observed. When 
the fish was preserved after 25 days, it retained 
its melanistic coloration in alcohol. 
During the lousefish’s 2 5 -day confinement, 
the color of the pool walls changed markedly 
as the diatom Melosira proliferated from es- 
sentially nothing to a growth 2 inches thick. 
The fish’s gradual color change paralleled this 
growth. The darkening may have been caused 
by a general increase in the amount of melanin. 
On the other hand, a faculty for rapid color 
change has been reported for Echeneis naucrates 
(Beebe and Tee-Van, 1933:222; Nichols in 
LaGorce, 1939:163; Sanborn, 1932:89; Town- 
send, 1927:171) and for Remora remora 
(Maul, 1956:50, 66), and thus it is possible 
that the observed changes were highly trans- 
itory. 
Another explanation for this color change 
derives from observations on echeneids which 
regularly attach. These fish have been stated 
either to lack countershading (Cott, 1940:43; 
Fincher, 1948:283) or to have reversed coun- 
tershading (Norman and Fraser, 1949:176). 
A lack of countershading supposedly results 
from a failure to maintain constant orientation 
to a light source; a reversal of countershading 
arises from the fact that the echeneid’s belly 
is usually more brightly illuminated than its 
back. The first explanation possibly fits the 
color change described above for the lousefish. 
When captured it had normal countershading, 
but began to lose it after a period in which 
swimming was often inverted or on the side. 
When free in the pelagic environment the 
lousefish presumably swims in a normal attitude. 
REFERENCES 
American Fisheries Society, i960. A List of 
Common and Scientific Names of Fishes 
from the United States and Canada. Am. 
Fisheries Soc., Ann Arbor, Spec. Publ. 2, 
102 pp. 
Beebe, W., and J. Tee-Van. 1933. Field Book 
of the Shore Fishes of Bermuda. G. P. 
Putnam’s Sons, New York and London, xiv 
+ 337 pp., 25 pis., 112 figs. 
Cott, H. B. 1940. Adaptive Coloration in 
Animals. Oxford Univ. Press, New York, 
xxxii -j- 508 pp., 49 pis., 84 figs. 
Jordan, D. S. 1907. Fishes. Henry Holt and 
Co., New York, xv -|- 789 pp., 18 pis., 673 
figs. 
and B. W. Evermann. 1898. The 
Fishes of North and Middle America. Bull. 
U. S. Natl. Mus. (47), Part 3, pp. xxiv -f- 
2183-3136. 
Lagorce, J. O. (Ed.) 1939. The Book of 
Fishes. Natl. Geogr. Soc., Washington. 367 
pp., illus. 
Maul, G. E. 1956. Monografia dos peixes do 
Museu Municipal do Funchal. Ordem Disco- 
cephali. Bob Mus. Funchal (9)23:5-75, 5 
figs., 21 tables. 
Menzies, A. 1791. Descriptions of three new 
