On a Skin Disease and a Nematode Parasite of a Dolphin,Tursiops truncatus (Montagu, 1821)
By
TOSHIKAZU HOSHINA and YASUO SuGIURA(Tokyo University of Fisheries)

Present paper deals with a skin disease due to a fungus and nematode parasite both found in a bottle-nosed dolphin, Tursiops truncatus(MONTAGU, 1821) which died in a pond of Yatsu Pleasure-ground at
Yatsu sea-shore of Chiba Pref.
The animal was a female, 266 cm in length, 180 kg. in weight andwas captured at the sea-shore of above-mentioned place on July in 1954
and attacked by a skin disease on December of that year, since thenthe animal gradually grew weak and died in the middle of the next month.
At first the skin became relaxation and on January of next year
numerous nodules appeared on the skin.
Besides the skin disease, the animal was showing slight scoliosis.
By the dissection, myositis caused by a bacterial infection and two cestodelarvae were found at the part, moreover acute pnemonia was found. The
scoliosis may be arisen from these pathological conditions.
A swimming pool merely divided by wire-netting and with thebottom of mud has been used to rearing the animal. Therefore thekeeping condition was not fitted for the animal in various point. Asthe food, fish-flesh have been used. Probably, the unsuitable rearing
made the animal weaken and lead to the diseases.
We have been studied the skin disease and nematode parasite ofstomach, by used the materials preserved in formalin which obtained
from the animal at the autopsy.
The investigation proved that the skin disease was due to a parasitic
fungus and the nematode parasite was a larval form belonging to thegen us Anisakis.
The skin disease should be diagnosed as Dermatomyosis accompaniedwith acute inflammaticula.
Probably fungoid diseases in sea mammalia may not yet unrecorded
except only following note in the Discov. Rep. Vol. 17, p. 126-MATTHEWS,
L. H.: "A pathological condition of the skin of the head was observedin two male whales at South Georgia and was noted as fungoidgrowth?"
Although, it seems that there is no relation between the skin134

T. HOSHINA and Y. SUGIURA

disease and the nematode parasite, we wish to report here the resultsof the studies.
We wish to acknowledge our indebtedness to Dr. M. NISHIWAKIof the Whales Research Institute who have kindly placed the materials
our disposal on which the present study was based and we must express our hearty thanks to Dr. Hideo OMURA the Director of the Institute,
who kindly offered them facilities for the publication of the report.
Skin Disease of a Bottle-Nosed Dolphin
1.

Materials and Methods

The block of affected skin of a bottle-nosed dolphin, Tursiops truncatus (MONTAGU, 1821) preserved in formalin were used for the study.
The materials were sectioned under celluloidin or parrafin method, andstained with Mayer's acid haemalaum and eosin, Heidenhains ironhaematoxylin, and other staining methods.
Besides the study by sectioned preparations, we studied the parasite
separated from the skin tissue by dissecting the materials soaked in
3% H202 or 10% HN03 or 10% NaOH solution for a while to makethem soften ed.
2.

Macroscopic Figures (pl. I, figs. 1-2)

Numerous discrete conical nodules measured 21-3& x 16-27 mm indiameter, 5-8 mm in height were observed on the skin of latter half ofthe trunk. They were somewhat soft, and coloration was not discriminatedcompared with the normal skin. In the center of well developed nodule
remained the tissue in columnar surrounded by peripheral eroded tissue.
The cut-section of the nodules showed no fundamental differencesin the findings compared with that of normal skin but it was tainted
partially by blood cells.
3.

Microscopic Figures (pl. I, figs. 3-4)

The outline of structure of normal skin as follows: The epidermis,
stratum germinativum consisting from pavement epithelium in the upperlayer, somewhat polygonal or cylindrical cells in the middle layer andundifferentiated cells in the basal part and with thin stratum semicorneum.
From the thin corium layer, corium-papillae with blood capillaries areprojected into the stratum germinativum and there is a cavity filledwith colloidal substances at the end of each papilla.

On a Skin Disease and a Nematode Parasite of a Dolphin

135

The corium is consisting from the network of fibrous connective
tissue with blood capillaries.
The subdermal tissue is very thick and consisting from fatty andfibrous connective tissue.
The lesion was characterized by proliferation of epithelial tissue
and swelling of corium-papillae. Somewhat swollen cells occurred in theupper to middle layer of the lesion and some of them became necrotic
and showed vacuolated degeneration, chromatolysis and picnosis. And
the layer showed at places longitudinal running plicae originating fromthe disintegration of the cells under the tissue pressure.
The proliferated cells occurring in the middle to lower layer werecylindrical or spindle form and not discriminative in general configuration to those of epithelial cells of normal skin but in the central part
they became spindle and arranged more compact.
As shown pl. I, fig. 3 the tissue underlying the degraded tissue
showed numerous cavities arosed by liquefy of the proliferated tissue.
The corium-papillae extremely enlarged and ruptured completely andfilled by blood cells especially polynuclear leucocytes. Some of them
contained the like of thrombus.
The skin disease was assignable to a parasitic fungus inhabitedin the epidermis, and it was found mainly in the upper layer of the~lesion.

4.

Morphological Characters of the Fungus (pl. II. figs. 1-5)

Pl. II. fig. 1 shows the general configuration of the fungus. It
grows penetrating and branching in the epithelial tissue of the lesion.
The mycelium is divided by septae and measuring 2.1-6.4µ in diameter.
Vesicular bodies formed by swelling of the mycelium at the distal
ends were observed in the upper layer of the lesion. They were measured 14.7-48.6µx14.1-37.1 µ in size and contained coiled mycelium
which was well stainable with haematoxylin. They may be copulatoryorgan of the fungus (pl. II. fig. 2).
The spore formation was observed on the hyphae found in collapsed
parts or tissue cavities of lesion. The spores were numerous, welldeveloped, and covered with brownish thick-wall, and were almost circularor ovid or rearly spindle form. The circular or ovid spores were 3.611.4 µ x 3.0-6.7 µ, the spindles 9.9-12.0 µ x 2.6-3.9 µ in size (pl. II. fig. 3).
They were pleurogenous and isolated or clustered on the vegetative
mycelium (pl. II. fig. 4).
Germination of the spores was observed in the lesion. The germ
tubes were well stained with eosin and measured 2.1-2.9 µ in diameter(pl. II. fig. 3).

136

T. HOSHINA and Y. SUGIURA

The arthrospore was formed at the tip of mycelium and each cell
was circular or ovid and 6.5-12.0 µ x 6.4-8.6 µ in size (pl. II. fig. 5).
Judging from the above-mentioned characters, the fungus may beplaced in the genus Trichophytum MALM. 1848 according to the classification of CLEMENTS and SHEAR (The Genera of Fungi, p. 231, 1931).
The specific determination requires further studies.
5.

Summary

We studied a fungoid skin disease found in a bottle-nosed dolphin,Trusiops truncatus (MONTAGU, 1821) which died in a rearing pond at
Yatsu Pleasure ground, Yatsu sea shore of Chiba pref.
1. The disease formed many characteristic conical nodules ruptured
at the tip on the skin.
2. The nodules consisted of the proliferated epithelial cells andthe extremely enlarged corium-papillae filled with blood cells, especiallypolynuclear leucocytes and were found parasitized by a kind of parasitic
fungus. The proliferation of the epithelial cells was caused by thefungus, which was found in the epithelial tissue of the lesion.
3. The fungus was parasitic type and was identified with the genus
Trichophytum MALM. 1848 previsionally.
Nematode parasite

Forty-one individuals of all immature specimens were obtained fromthe stomach of the same host.
The morphological characters of the parasite (textfigs. 1-4) are
as follows: Body 17 .0-30.0 mm. in length, 0.4-0.6 mm. in breadth; cuticle
presented a series of fine rings and a pair of cervical papillae at thelevel of 0.4-0. 7 mm. from anterior end. Head truncated, consisting of
three large lips; dorsal lip nearly tetragonal provided with double
papillae at the both corner; two subventral lips nearly triangular withdouble papillae at outside; each lip with dentigerous ridge and indented
in the middle; interlabia absent; mouth triangular; Esophagus divided
into an anterior muscular part and a posterior straight ventriculus, theformer measured 2.32-3.38mmx0.17-0.28mm the latter 1.ll-1.25mmx
0.20-0.28 mm. Intestine straight and thick walled with numerous fold;rectum short; anus situated 0.16-0.21 mm. from posterior end. Nerve
ring situated 0.3-0.4 mm. from anterior end. Excretory pore locatedbetween subventral lips; reproductive organ undeveloped but origin ofspicule sac with 0.06-0.08 mm x 0.04-0.06 mm in size observed under therectum. Tail bluntly conical with numerous caudal papillae.

On a Skin Disease and a Nematode Parasite of a Dolphin

137

Textfig. Anisakis sp. parasitic in the stomach of the bottle-nosed
dolfin, Tursiops truncatus (MONTAGU, 1921)
Fig. 1. Head, end viewFig. 2. Head, ventral viewFig. 3. Posterior extremity
Fig. 4. Ventriculusan, anus; d. r, dentigerous ridge; es, esophagus; ex. p, excretory pore;int, intestine; m, mouth; pap, papillae; re, rectum; sp. s, spicule sac;ven, ventriculus.

Judging from the characteristics of the head of the nematode, it
may be immature form of Anisakis catodontis BAYLIS, 1929. Summary:
A larval form of nematode parasite obtained from the stomach ofTrusiops truncatus (MONTAGU, 1821) was descrived to be identified withthe genus Anisakis.

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T. HOSHINA and Y. SUGIURA

Literature Cited
Baylis, H. A.: On the classification of the Ascaridae. I. The systematic value of certain
characters of the alimentary canal. Parasitol., 12, 3, 253-64 (1920).
An Ascarid from the Sperm-Whale. Ann. Mag. Nat. Hist. (9), 11, 211-17 (1923).
Parasitic Nematoda and Acanthocephala collected in 1925-1927. Discov. Rep. 1,541-60 (1929).
A list of worm parasitic in cetacea. Discov. Rep. 6, 393-418 (1932).
Clements, F. E. and Shear, C. L.: The Genera of Fungi (1931).
Henrici's, A. T.: Molds, Yeasts, and Actinomycetes. Second Edition. (1948).

PLATE

T. HOSHINA and Y. SUGIURA

Explanation of Plate I.
1.

Showing the general configuration of the diseased bottle-nosed dolphin,Tursiops truncatus (MONTAGU, 1821).
2. Showing the well developed lesion.
3. Showing the longitudinal section of the lesion, stained with van Gieson'sstain; EP, proliferated epithelial tissue; Pl, normal corium-papilla; P2, abnormalcorium-papilla.
4. Showing the enlarged corium-papilla filled with blood cells especially polynuclear leucocytes stained with Mayer's acid heamalaum and eosin.

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Explanation of Plate II.
Showing the general configuration of the genus Trichophytum sp., found parasitic in the skin of Tursiops truncatus (MONTAGU, 1821).
1. Mycelium in the epithelial tissue.
2. Copulatory organ.
3. Aleurispores and the germinating spores.
4. Aleurispores.
5. Arthrospores.

T. HOSHINA & Y. SUGIURA

Sci. Repts. Whales Res. Inst., No. 11, 1956. Plate II

235~oO
0.05mmfor Figs. 1. 2. 3. 4. 5.
0.01 mmfor Fig. 3.