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九州西方海域産小型歯鯨類の研究―12 : 長崎県橘湾沿岸で捕獲されたスナメリについて


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Title: 九州西方海域産小型歯鯨類の研究―12 : 長崎県橘湾沿岸で捕獲されたスナメリについて
Other Titles: Studies on the Little Toothed Whales in the West Sea Area of Kyusyu―XII.Neomeris phocaenoides, so-called Japanese "SUNAMERI", caught in the coast of Tachibana Bay, Nagasaki Pref.
Authors: 水江, 一弘 / 吉田, 主基 / 正木, 康昭
Authors (alternative): Mizue, Kazuhiro / Yoshida, Kazumoto / Masaki, Yasuaki
Issue Date: Feb-1965
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.18, pp.7-29; 1965
Abstract: As a result of the investigation of eighteen Neomeris phocaenoides CUVIER which had beed caught in the coast of Tachibana Bay and landed at Nagasaki fish-market, the following characteristics have been ascertained. 1. The body color of this species is, in general, silver-grey, but is slightly light in its color in the part from the front of the larynx nearly to the anus. Their body color is usually changed to black, when it is made into sample by the fixation or left as it is. Therefore it has been mistakenly reported since olden time that the fresh body color of this species is black. 2. The head of this species is smaller than that of other species, with no snout. The forehead part and upper lip are similar to those of Globicephala melaena. And this whale has no dorsal fin but has a rising growing in wide line at the back, in exchange for the dorsal fin, and many little dots are found in that rising. The histological section of the rising, through the epidermal dot, is shown in Plate IN-15. 3. The percentage of the fins to the body length in this species is larger than that of other species; and the posterior margin of the pectoral fin does not take the wave from. 4. In other kinds of the little toothed whales, the growth of body length is believed to be almost due to the growth of the tail part of such whales as Tursiops sp. and Pseudorca sp., but the growth of the body-length of this species is due to the growth of the abdominal part. 5. To speak of the skull of this species, the extreme rising at the fore part of the nares on os incisivum is characteristic, while os pterygoides, when viewed from the palate, is complicated. The skull measurement of this species are shown in Table 2. 6. The number of vertebra is shown in Table 3. Of the cervical vertebrae, 1st.-3rd. adhere to all specimens. 7. The number of os costale, two-headed os costale, and cartilago, and their connection to vertebrae and sternum are shown in Table 4 and Fig. 5. 8. The form of sternum is interesting to see. It is a short, wide and single bone, and does not consist of three bones, quite different from that of other kinds the of little toothed whales. 9. The scapula of this species has a characteristic form. It is considered generally that the scapula of the little toothed whales is characteristic in form according to their kinds. 10. The number and the form of teeth is shown in Table 5, Fig. 6 and Plate III-10, 12. The form and arrangement of teeth in this species is very characteristic. 11. It seems that Neomeris phocaenoides is delivered of its cub in the coast of Nagasaki Prefecture between the last ten days of August and the first of September. This toothed whale takes the small sardin, small horse-mackerel, squid and other coastal little fishes, namely it has omnivorous nature. 12. In the case of male, there is no mammary slit on both side of the reproductive aperture, and there is a little cavity between the anus and reproductive aperture as shown in Plate II-8. This is the vestige of teat. 13. The authors regret that they can not find the values of this species caught in other sea areas, and confirmed by other authors in regard to the external proportions, the skull measurment, the number of vertebra, os costale, cartilago costale and the teeth, as there is scarcely any such trustworthy values of measurment to be relied upon. / 1963年9月・10月,長崎県橘湾沿岸で捕獲され,長崎魚市に水揚げされたスナメリ(Neomeris phocaenoides CUVIER)の内18頭(雄12頭,雌6頭)について諸観察測定を行い,本種の特徴について検討した結果,次の事が明らかになった, 1.本種の体色は,下吻下面より肛門附近までは幾分淡色をなしているが,大体に於て全身銀灰色である.固定液で標本にした場合や,そのまゝ長く放置した場合には,普通体色は黒変する.昔から本種の体色は黒色であると報ぜられているのは,この為であろう. 2.本種の頭部は他に比べて非常に小さい.又吻は突出していなくて前頭部及び上唇部はGlobicephala melaenaに良く似ている.又本種には背鰭がない.その代りに背部に隆起部が巾広帯い状に発達していて,その隆起部には細い突起が多数存在している.その突起の部分を通る隆起部の組織学的な切片の状態はP1. IV-15に示した. 3.本種の鰭の体長比は他の種類の小型歯鯨よりも大きい.特に胸鰭はその傾向が強い.又胸鰭後縁は波状をなしていない. 4.他の種類の小型歯鯨類ではその体長の成長は主としてその尾部による所が大であったが,本種に於ける体長の成長はその胴部の伸びが主として貢献している.これは本種が沿岸性の小型歯鯨である事を物語っていると思われる. 5.本種の頭骨には切歯骨の鼻孔前方に存在する甚しい隆起が特徴的であり,その他形態上の特徴は口蓋面より見た翼状骨の形が複雑である等.又本種の頭骨計測結果はTable2に示した. 6.脊椎骨数の計測結果はTable3にかゝげた.本種の頸椎骨は大体に於て最初の三つが癒着していた. 7.肋骨・肋軟骨数及び夫等と脊椎骨・胸骨との結合状態等についてはTable4,Fig.5に示した. 8.本種の胸骨は非常に特徴ある形態をして居り,他の種類の小型歯鯨類の胸骨に於ける如く,胸骨柄・胸骨体・剣状突起の三つの骨から成立っていなくて単一骨である.その長さは短くて,巾広い. 9.本種の肩甲骨は特徴ある形をしている.肩甲骨は各種の小型歯鯨でその形態に良く特徴が出ていると思われる. 10.本種の歯数はTable5に示した.本種の歯の形及び歯の配列状態は特徴的である. 11.本極は長崎県沿岸では8月下旬より9月初旬に分娩するものと思われる.又本種は雑食性で沿岸の小型魚例えば小アジ・小イワシ及びイカ類を餌として摂取している様である. 12.本種の雄には生殖孔の両側に乳溝はない.又生殖孔と肛門の中間に一つの小盲嚢が存在している.これは退化乳頭であると考えられる. 13.他に信頼出来る測定値が殆んどないので,体長プロポーション・頭骨計測・脊椎骨数・肋骨・肋軟骨・歯数・等他の海域産のものと比較出来ないのは残念であった.
URI: http://hdl.handle.net/10069/31550
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第18号

Citable URI : http://hdl.handle.net/10069/31550

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