DIATOM FILMS ON WHALES IN SOUTH
AFRICAN WATERSTAKAHISA NEMOTQ 1 i, PETER B. BEST 2 l
KIMIE ISHIMARU 1 > AND HIDEAKI TAKAN0 3 >2)I) Ocean Research Institute, University of Tokyo, Tokyo
Sea Fisheries Institute, Department ef Agriculture and Fisheries, Cape Town
3) Tokai Regional Fisheries Research Laboratory, Tokyo

ABSTRACT

Diatoms found on the skin of minke whales and 4 species of toothed
whales in the waters off South Africa were examined. Typical Cocconeis ceticola was common on minke whales and was also found on a southern bottlenose whale. C. ceticola f. constricta was, on the other hand, found only ona southern bottlenose whale and C. ceticola f. berardiusii was found on a Cuvier's
beaked whale. Stauroneis orympica was found on a Cuvier's beaked whale, akiller whale and a strap-toothed whale. Gomphonema aestuarii and Synedra sp.
were also found on a strap-toothed whale, while an unidentified Navicula sp.
was also found on a minke whale and a strap-toothed whale.
On the assumption that typical C. ceticola is only contracted in high latitudes, its occurrence on whales in the waters off South Africa shows that theseanimals may recently have migrated from colder waters.
INTRODUCTION

Many diatom species on whales have been described in the North Pacific andin the Antarctic (Hart, 1935; Hustedt, 1952; Nemoto, 1956, 1958). Diatom films
on the skin of whales have been mostly found in the waters of high latitudes, and they
have generally been considered common in the colder waters of both hemispheres.
There are few observations of diatoms on whales caught in the waters off South.
Africa (Mackintosh and Wheeler, 1929; Best, 1969). It is generally accepted thatdiatoms (mainly Cocconeis ceticola and its related forms) propagate and form films on
the skin of cetaceans in colder waters and are not so common in temperate waters,
although Gambell (1972) has speculated that the lack of ectoparasites on whales
at Durban may have been due to the greater rate of epidermal decomposition in
the higher sea temperatures prevailing there.
In recent studies of whales caught or stranded on the coast of South Africa,
22 specimens of diatom films from skin or teeth have been collected. These specimens are examined taxonomically and the occurrence of diatoms as skin films ofwhales is discussed in relation to hydrographic conditions.

Sci. Rep. Whales Res. Inst.,
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NEMOTO, BEST, ISHIMARU AND TAKANOMATERIALS AND METHODS
Diatom samples were collected between 1969 and 1973 by one of us (Best)
from whales caught or stranded around South Africa. Host species included bothbaleen and toothed whales (Table 1 ).
Diatom specimens were mostly collected from the skin but one diatom film wascollected from the teeth of a strap-toothed whale. The samples from minke andbottlenose whales were collected immediately after death while they were alongside or on the deck of the catcher. Those from the other species were collectedfrom stranded animals some unknown time after death. All samples were preservedin 10% formalin/sea water with the skin of the whales. The diatom samples werethen scratched from the skin and washed with distilled water and rinsed three orfour times. After preservation in potassium permanganate for 24 hours, hydrochloric acid was added and the samples kept for a further 24 hours. After boiling for
5 minutes, the samples were washed and rinsed several times, and frustules of diatoms were kept on plates. Double coating of carbon and gold was used for electron
TABLE 1.
Specimenno.

DIATOM SAMPLES* FROM WHALES FROM SOUTH AFRICA

Date
collected

Species

Length(m)

Sex

Localityt

69/10

July

5 '69

Killer whale (0. orca)

6.10

M

73/10

Oct. 25 '73

5.77

F

75/1

Jan.

19 '756.43

M

33°361 S 28°041 E

78/15

Apr.

6 '78

Cuvier's beaked whale(<;. cavirostris)
Southern bottlenose
whale (H. planifrons)
Strap-toothed whale(M. layardii)
Minke whale(B. acutorostrata)

Bordjies Drif
Cape Point
Still Bay

5.46

M

Milnerton

8.53

M

29°301 s 32°51 1 E

7.62
9.14
7.62
7 .92
8.23
8.23
8.23
8.23
8.84
9.14
8.64
8.28
8.15
8.28
8.86
8.43
8.61

M
F
F
F

U71/2200

Aug. 28 '71

U71/2201
U71/2202
U71/2203
U71/2211
U71/2232
U71/2243
U71/2245
U71/2313
U71/2315
U73/1255
U73/1256
U73/1299
U73/1304
U73/1306
U73/1446
U73/1559
U73/1839

Aug. 28 '71
Aug. 29 '71
Aug. 29 '71
Aug. 30 '71
Aug. 31 '71
Sept. 5 '71
Sept. 5 '71
Sept. 16 '71
Sept. 18 '71
June 24 '73
June 24 '73
June 26 '73
June 27 '73
June 27 '73
July 17 '73
July 29 '73
Sept. 28 '7"3

M
M
F
F

M
M

29°57 1 s 31°19 1 E
30"461 s 31°19 1 E
30"48 1 s 31°58 1 E
31°101 s 30"551 E
31°06' s 31°01 1 E
31°11 1 s 30"461 E
31°051 s 31°47 1 E
30"04 1 s 31°35 1 E
30"42 1 s 33°25 1 E

F
M

M
M
M

31°10' s 31°01 1 E
30°321 s 31°491 E
30"22 1 s 32°04 1 E
31°15 1 s 31°25 1 E
30"27 1 s 31°17 1 E
29°45' s 32"12' E

MF* All samples taken from skin except 78/15 where sample taken from teeth.
t All animals collected at sea apart from 69/10, 73/10 and 78/15, which were all stranded animals.

Sci. Rep. Whales Res. Inst.,
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DIATOM FILMS ON WHALES

microscopy. The specimens were examined with both scanning and ordinary electron microscopes.
The scanning electron microscope JSM-35 was mainly used for the identification of species. Some species are still under examination, but their preliminary
identification is described in this paper.
DESCRIPTION OF SPECIESThe species of diatoms identified and the host species of whales involved areshown in Table 2.
TABLE 2. DIATOMS OCCURRING ON THE SKIN AND TEETH
OF WHALES IN THE WATERS OFF SOUTH AFRICA
Minke whale

Cocconeis ceticola(typical form)
C. ceticola f. constricta
C. ceticola £ berardiusii
Stauroneis olympica
Navicula sp.
Gomphonema aestuarii
Synedra sp.

Southernbottlenose
whale

Cuvier's
beakedwhale

Killerwhale

Straptoothed
whale

18

Only pennate diatoms were found in the diatom films examined. There wereclear differences between the diatom species on different host whales. The typicalform of Cocconeis ceticola Nelson was found on every minke whale but only a very
few individuals on one of the toothed whales examined (southern bottlenose whale).
On the skin of the southern bottlenose whale, some specimens of C. ceticola were
somewhat deformed and a clear constriction was observed. The edge of the valves
was sometimes absent as shown in Fig. F in Plate I. Small numbers of a slender
form of C. ceticola were also found on this whale. On the Cuvier's beaked whale
the more slender form of C. ceticola was found, but with no constriction at the edge
where the stauros of the lower raphe reaches the edge. This type of C. ceticola has
been found previously on the skin of Baird's beaked whale Berardius bairdii (Kriashtorin, 1962), and is named as the form berardiusii.
The constricted form of Cocconeis ceticola has often been observed in toothed
whales. As indicated in Plate I F, the constricted parts sometimes lack the outeredge of the valve, and the hole on the inside is deformed as indicated in Plate I H.
The hole in the edge of typical Cocconeis ceticola is rather similar to other holes along
the edge (shown in Plate I B, C) or a little deformation is observed as shown in
Plate I E.
Four other species of pennate diatoms were found on toothed whales. Stauroneis olympica Hustedt was found on the Cuvier's beaked whale, killer whale andstrap-toothed whale. This species has clear pseudosepten from the tips of the cell,
Sci. Rep. Whales Res. Inst.,
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NEMOTO, BEST, ISHIMARU AND TAKANO

which is different from the pseudosepten and the shape of the tip of S. omurai N emoto(Nemoto, 1956) found on sperm whales in the North Pacific. The shape of S.
olympica as originally described (Hustedt, 1952) is more slender than these specimens
and the structure of the stauros may be somewhat different. However, considering
the varieties within one diatom species on different species of whales, these specimens may be attributed to the Stauroneis olympica complex. The closely related species S. aleutica reported by Nemoto (1956) can also be put in this group. Stauroneis
diatoms were also present on sperm whales off South Africa, Chile and Australia(Best, 1969). The presence of Navicula species (possibly Stauroneis olympica, as described from the epiphytes on barnacles on a humpback whale from the Antarctic)
was described on a sperm whale landed in the Outer Hebrides (Hart, in Clarke,
1956). This species is possibly cosmopolitan or bipolar on sperm whales and toothed whales (Hart, in Best, 1969).
Small naviculoid diatoms were found on the strap-toothed whale, and werealso found in the film of Cocconeis ceticola on the skin of one minke whale. Gomphonema aestuarii Cleve which is also described by Giffen ( 1966) in South African
waters, and Synedra sp., which is very close to S. tabulata (Ag.) Kupzing (Harrison
and Thurley, 1974), were also found on the teeth of this strap toothed whale.
DISCUSSION

Studies of skin films of Cocconeis ceticola have suggested that these diatoms aremost common on cetaceans in the colder water of high latitudes.
Mackintosh and Wheeler (1929) concluded that such diatom films on whales
are undoubtedly contracted in the austral summer in Antarctic or sub-Antarctic
waters. Hart (1935) described the general tendency for the rate of diatom film
infestation of blue and fin whales to increase as the season progressed at South
Georgia. Gambell (1968) also noted the diatom infestations on sei whales caught
at South Georgia; and that sei whales newly arrived from the breeding grounds inthe middle of the summer season do not bear diatoms. However, Mackintosh andWheeler (1929) also noted that small spots of C. ceticola were seen on a few immature (fin and blue) whales at Saldanha Bay, South Africa. Best (1969) and Bannister (1969) recorded the presence of C. ceticola on sperm whales (mostly large or
medium-sized males) off Donkergat (South Africa) and Albany (Western Australia) respectively, during the autumn and winter. Cocconeis diatoms have also beenrecorded from whales in the Eastern Pacific off South America (A. Aguayo L., pers.
comm.). Clarke (1956) found no clear infestation with diatoms of Cocconeis typeon the sperm whales caught in the Azores.
Diatoms in the northern part of the North Pacific, where many diatoms arefound on the baleen and sperm whales, have been described by Nemoto (1956).
Diatom infestation is common in the Bering Sea and its adjacent waters, while inthe coastal waters, Cocconeis diatoms are often observed on both sides of the Pacific;
off British Columbia (Pike, 1953) on the eastern side, and in the Okhotsk Sea andoff Hokkaido waters in Japan on the western side (Omura, 1950). Cocconeis cetiSci. Rep. Whales Res. Inst.,
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DIATOM FILMS ON WHALES

101

cola Nelson is the most common diatom on baleen whales. The varieties and formsof C. ceticola in the North Pacific have been described and discussed by Usachev(1940), Nemoto (1956, 1958), Nemoto et al. (1977) and Kriashtorin (1962). According to these authors, the typical Cocconeis ceticola form is only described frombaleen whales. Kriashtorin (1962) reported some large-sized C. ceticola as a newvariety, C. ceticola var. arctica, but this is clearly the same type of C. ceticola fromits shape and size. The fact that the typical form of C. ceticola has now been foundon the skin of minke whales caught off South Africa suggests that minke whales
are similar to other rorquals as host-types. C. ceticola has also been recorded fromminke whales in the Antarctic (Ohsumi et al., 1970), but no remark was madeconcerning the type of C. ceticola involved.
Cocconeis ceticola f. constricta Nemoto is found on the skin of sperm whales in the
North Pacific (Nemoto, 1956). C. ceticola has also been recorded from sperm whales
off Donkergat, South Africa (Best, 1969) and off Albany, Western Australia (Bannister, 1969) : no distinction was made, however, between form constricta and typical ceticola. Cocconeis diatoms found on the Hyperoodon planifrons in the waters off
East London, South Africa, were of two types. A very few specimens of typicalC. ceticola forms were found, but the rest were all constricted forms. Constricted
forms found in this study show some variation although there was no clear boundary to separate them. One was typical C. ceticola f. constricta which was previously
found on sperm whales (Nemoto, 1956). Kriashtorin (1962) also described thesame type from sperm whales in the Far Eastern seas. It was clearly shbwn that theedge of the raphe-valve where the stauros reaches was absent or deformed. The
second type of constricted form was similar to C. ceticola f. berardiusii which was firstdescribed by Kriashtorin (1962) from Berardius bairdii. This type (Kriashtorin,
1962 in Fig. le) is the same as the type M in Fig. 3 in Nemoto (1958), and wascommon among the diatoms on thecavirostris examined in this paper. As no
Cocconeis specimen was found on the killer whale in this study, it is difficult to as-,sess the position of Cocconeis orcii Kriashtorin described by Kriashtorin (1962).
From the surface structure shown by him, C. orcii is one variety of C. ceticola and is
not a valid species.
The global distribution and occurrence of parasitic diatoms on whales are interesting. As stated previously, Cocconeis diatoms are mainly described from thehigh latitudes of the North Pacific and Southern Hemisphere, where they can form
films over a large part of the body (Bennett, 1920). Cocconeis diatom infestation onwhales in lower latitudes is usually rarer and much smaller in extent ("small spots"Mackintosh and Wheeler, 1929), so it might be concluded that such animals arerecent migrants from higher latitudes. The only resident cetacean population outside the Antarctic known to carry Cocconeis films is the Franciscana dolphin, which
lives in water from 13-23°C (Nemoto et al., 1977). Presumably therefore it is possible to contract Cocconeis films in water as warm as 13°C, but as little is known
about the seasonal incidence of diatoms on or movements of the Franciscana dolphin it is impossible to give an upper limit to the temperature range in which C.
ceticola can survive. On the assumption that the films of Cocconeis on the largerz.

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NEMOTO, BEST, ISHIMARU AND TAKANO

102

cetacea are contracted only in high latitudinal waters, the presence of C. ceticola onminke whales off Durban from June to September indicates that the animals haverecently arrived from colder waters, and that the migration may be more protracted
over time than for other baleen whale species. The presence of Cocconeis films on
H. planifrons andcavirostris off South Africa is the first indication that these
species may also migrate from Antarctic or sub-Antarctic to warmer waters.

z.

ACKNOWLEDGEMENT

We would thank Mr G. Smith, boatswain of the whale-catcher C. G. Hovelmeiner for his kind assistance in collecting diatom samples from minke whales in
1973.
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BENNETT, A. G., 1920. On the occurrence of diatoms on the skin of whales. Proc. Roy. Soc. London, 91: 352-

357.
BEST, P. B., 1969. The sperm whale (Physeter catodon) off the west coast of South Africa. 4. Distribution
and movements. Invest. Rep. Div. Sea Fish. S. Afr., 78: 1-12.
CLARKE, R., 1956. Sperm whales of the Azores. Discovery Rep., 28: 237-298.
GAMBELL, R., 1968. Seasonal cycles and reproduction in sei whales of the Southern Hemisphere. Discovery Rep., 35: 31-134.
GAMBELL, R., 1972. Sperm whales off Durban. Discovery Rep., 35: 199-358.
GIFFEN, M. H., 1966. Contributions to the diatom flora of South Africa-III. Diatoms of the marine littoral regions at Kidd's Beach near East London, Cape Province, South Africa. Nova Hedwigia, 13 (I &2): 245-292, 5 pls.
HARRISON, R.J. and K. W. Thurley, 1974. Structure of the epidermis in Tursiops, Delphinus, Orcinus andPhocoena. pp. 45-71. In: R.]. Harrison (ed.), Functional anatomy efmarine mammals. Academic Press.
HART, J., 1935. On the diatoms of the skin film of whales, and their possible bearing on problems of whale
movement. Discovery Rep., 10: 247-282.
HusTEDT, F., 1952. Diatomeen aus der Lebensgemeinshaft des Buckelwals (Megaptera nodosa Bonn.). Arch.
Hydrobiol., 46: 286-298.
KRIASHTORIN, L.B., 1962. The diatoms of the skin film of whales in the Far-Eastern seas. Trucfy Inst.
Okeanol. A. N. U.S.S.R., 58: 314-321.
MACKINTOSH, N. A. and J.F.G. Wheeler, 1929. Southern blue and fin whales. Discovery Rep., 1: 257-540.
NEMoro, T., 1956. On the diatoms of the skin film of whales in the northern Pacific. Sci. Rep. Whales Res.
Inst., II: 99-132.
NEMOTO, T., 1958. Cocconeis diatoms infected on whales in the Antarctic. Sci. Rep. Whales Res. Inst., 13:

185-191.
NEMOTO, T., R. L. BROWNELL, ]R, and T. lsHIMARU, 1977. Cocconeis diatom on the skin of Franciscana.
Sci. Rep. Whales Res. Inst., 29: 101-105.
0HSUMI, S., Y. MASASKI and A. KAWAMURA, 1970. Stock of the Antarctic minke whale. Sci. Rep. Whales
Res. Inst., 22: 75-125.
OMURA, H., 1950. Whales in the adjacent waters of Japan. Sci. Rep. Whales Res. Inst., 4: 27-113.
PIKE, G. C., 1953. Two records of Berardius bairdii from the coast of British Columbia. j. Mamm., 34 (!):

98-104.
UsACHEV., P. I., 1940.
torin)

Diatoms propagation of the skin film of whales.

Z,ool. Z,h., 19 (2).

(In Kriash-

Sci. Rep. Whales Res. Inst.,
No. 32, 1980

DIATOM FILMS ON WHALESEXPLANATION OF PLATE
PLATE I
Figures A.D.F.G. are taken by light microscope, B.C.E.H.K.L. are taken byscanning electron microscope and l.J. are taken by Electron microscope.
A. *-raphevalve of Cocconeis ceticola Nelson typical form found on minke whale(B. acutorostrata) U73/1299. B.-raphevalve of C. ceticola ·typical form on minke
whale U73/1304. C.-raphevalve of C. ceticola typical form on minke whale U71/
2200. D.*-raphevalve of C. ceticola typical form on minke whale U71/2203. E.raphevalve of C. ceticola typical form on minke whale U71/2245. F. *-raphevalveof C. ceticola f. constricta Nemoto on southern bottlenose whale 75/1. G.-raphelessvalve of C. ceticola f. constricta on southern bottlenose whale 75/1. H.-raphevalveof C. ceticola f. constricta on southern bottlenose whale 75/1. I.*-Gomphonema aestuarii
on strap-toothed whale, 78/15. J. *-G. aestuarii on strap-toothed whale. K.Stauroneis olympica Hustedt found on killer whale 69/10. L.-S. olympica found on
killer whale 69/10.
* External views of valves, others are internal views.

Sci. Rep. Whales Res. Inst.,
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103

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