LIFE CYCLE OF CYAMUS SCAMMON! (AMPHIPODA:
CYAMIDAE), ECTOPARASITE OF GRAY
WHALE, WITH A REMARK ON THE
ASSOCIATED SPECIES
YUK M. LEUNG
Department of Biological Sciences, University
of Southern California, Los Angeles
ABSTRACT
G_vamus scammoni, parasitic exclusively on gray whale, was studied
under the provision of special scientific permit. Its life cycle was
completed during the journey of winter migration. C. ceti and C.
kessleri, messmates of C. scammoni, followed the same pattern in many
respects. Significantly, the whale-lice can survive out of water for
several days though other am phi pods are poorly adapted for terrestrial
life. The cyamid causes certain damage to the cutaneous tissue of the
host when the juvenile begins its livelihood.
INTRODUCTION
The whale-louse, ectoparasite of mysticete and odontocete, has been recognized
ever since Oniscus ceti of the bowhead whale recorded by Linnaeus in 1758.
Although scores of papers on taxonomy have elaborately been published, yet
many facets are still unexplored. This accounts for the fact that systematic
investigation is not always feasible, not only because the population of the
whale species is widely distributed in different hemispheres, but the cyamids
are often discarded by the commercial whalers. Moreover, the whales are
legally protected so that collecting is no longer available.
The gray whale, Eschrichtius robustus, summers in Chukchi, Beaufort, and
western Bering Seas for food, and in winter it migrates along the Californian
coast to the lagoons of Baja California, Mexico, for breeding and calving. As
the herd travels along a defined course in definite seasons, the life cycle of the
cyamid may well be traced through a successive survey during the entire
journey. Under the provision of the specific scientific permit, the author was
privileged to participate the whaling expedition on several occasions, and visited
the shore station at intervals to collect series of samples of which the accumative data were of significance to make this study possible.
MATERIAL AND METHOD
This study was based on series of Cyamus scammoni and the associated
species, C. ceti and C. kessleri, taken aboard the catcher boat off central CaliSci. Rep. Whales Res. Inst.,
No. 28, 1976, 153-160.
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GENERALCONSIDERATI
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LIFE CYCLE OF CYAMUS SCAMMON!
159
cyamids, particularly those of infesting larger mysticetes, have rigid host specificity and site restrictiveness (Leung l 970a) as C. scammoni occurs habitually
either on the delicate skin tissue of the belly or on the scar of the endemic
cirriped along both jaws of the whale; C. ceti, being received at the same
table occasionally with C. sca11imoni, is found generally on the creases of the
lips, flippers and flukes; whereas C. kessleri localizes only on the umbilicus,
genital opening and anal aperture of the host. During the whaling seasons,
nine whales had been inspected aboard the catcher boat and in the shore
station, and all animals were heavily infested with cyamids of different stages.
Among the three species, C. scammoni exceedingly predominated over the
other two.
The cyamids breathe by means of gills, however, it is remarkable that they
are able to exist beyond the environmental condition. At the shore station it
was not uncommon to see the whale-lice crawling for many hours after the
whale drawn from the sea. While cruising on the catcher boat, it was curious
to observe three individuals of C. scammoni reposing on a steel cable of the
winch in the late afternoon as no whale was taken during the day. Obviously,
these individuals had survived from the catch of the previous day. Further
surprising evidence was afforded by G.]. B. Ross of the Snake Parks and Oceanarium of S. Africa (per. comm.) who reported that the cyamids could outlive
for three days on a stranded south right whale at Algoa Bay in 1971. Integumentary respiration of the whale-lice is of considerable significance, because
they were able to survive for several days divorced from the aquatic environment even though the amphipods are poorly adapted for terrestrial life.
The mouth parts of the cyamid are for piercing. There is some likelihood
that whale-lice are omnivorous feeding on the algal filaments and the outermost layer of skin tissue of the host. However, the bill of fare seems to be
the cutaneous tissue of the host as the young customarily encases itself by
piercing the delicate skin tissue or embedding itself in the cleavages of the
sessile cirriped when it begins to maintain its livelihood. Since the host provides favorable sites and adequate food supplies, opportunity of building up
large population is eminent. On the other hand, the small streamlined odontocete
furnishes neither adequate accommodation nor profuse provisions, and the
survival rate is therefore in a reverse direction (Leung l 970b ).
Three species of cyamids occur on the gray whale. With the exception
of C. scammoni, the systematic status of C. kessleri and C. ceti have long been
bewildered. Although C. kessleri was recorded by E. Wosnessensky in 1864
at Metschigmensky in the vicinity of the Bering Strait, yet the host had not
been identified. It did not come to light until 1954 when Mohr (Hurley and
Mohr 1957) collected a few hundred individuals of this species from a gray
whale killed by the Eskimos off Pt. Barrow, Alaska, and the host proper was
finally justified. C. ceti was described from the bowhead or the Greenland
right whale, but the association with the gray whale is poorly known. Since
the bowhead and the gray whale inhabit in Arctic waters, the possibility of
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.
160
LEUNG
accidental transfer by bodily contact is not unlikely to happen. However, it
is seemingly not the case as our colleague, Dr. F. E. Durham, a bowhead biologist, reported that he found neither C. scammoni nor C. kessleri but C. ceti
on the bowhead (per. comm.). For this reason, the likelihood of interchange
seems unlikely. Virtually, C. ceti is akin to C. monodontis of the narwhal
which Lutken (1873) described it as a "peculiar dwarf-form" of C. ceti. In
view of C. ceti of the gray whale, there is reason to speculate that it may fall
within the original description from the bowhead, and a concept of specific
independent species has been conceived. Consequently, both species should be
thoroughly reviewed.
There are various unnamed species of chonotrichous ciliates (Chonotricha)
infesting the ventral surface of the young cyamids (Fig. 4). It is of interest
that these collar ciliates, alike the cyamids, demonstrate an extraordinary mode
of parasitism that shares on other congeners to occupy the same community,
and the occurrence of interchange is uncommon even though the messmates
are colonized at the adjoining locality. Accordingly, it is suggested that it
may be a contributing factor to identify the whale-lice and the cetaceans in
the presence of the ciliates.
Finally, the whale-lice cause certain damage to the whale skin when the
young begin to maintain their livelihood, and the injury is a result of piercing
the tissue in which they shelter for safety and for food. As a matter of fact,
the outermost layer of whale skin is extremely thin and delicate in structure,
hence it is no wonder that the unwelcome guests frequent these haunts for
living.
ACKNOWLEDGMENT
I am grateful to Mr. Dale W. Rice and Mr. Allen A. Wolman of the National
Marine Fisheries Service for their pertinent information and facilities; to Del
Monte Fishing Co. for permission to make observation in the factory ; and
particularly to the skipper and his crew members of the catcher boat " Allen
Cody" for their full cooperation to make this study possible. The use of the
library and laboratory of Allan Hancock Foundation is gratefully acknowledged.
REFERENCES
HcRLEY, D. E, and J. L. MOHR, 1957. On whale-lice (Amphipoda: Cyamidae) from the California gray whale E. glaucus. ]. Parasitol., 43(3): 352-357.
LEC'W, Y. M., 1965. A collection of whale-lice (Cyamidae: Amphipoda). Bull. Soc. Calij. Acad.
Sci., 64(3): 132-143.
LEC:-IG, Y. M., 1970a. Cyamus orcini, a new species of whale-louse (Cyamidae, Amphipoda) from
a killer whale. Bull. de Inst. Fundamental D'Afrique Noire, Universite de Dakar, T32, ser A, N'3:
669-675.
LEU'.'iG, Y. M., 1970 b. First record of the whale-louse genus Syncyamus (Cyamidae, Amphipoda)
from Western Mediterranean, with notes on the biology of obontocete cyamids. In: Investigation on Cetacea II. Univ. of Berne, Swirzealand, pp. 243-247.
LUTKEN, C. F., 1873. Bidrag til kundakab om arterne af slaegten Cyamus Latr. eller Hvallusene. Vidensk. Selsk. Skr., (5) 10(3) :t 229-284.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.