Stenella coeruleoalba; striped dolphin

Japanese: スジイルカ（英語表記）Stenella coeruleoalba; striped dolphin

It is a species of whale, male, delphinidae, genus. Males can reach a body length of about 2.6m, and females about 2.5m. Maximum body weight is about 156kg. Body length at birth is about 1m. The back is blackish gray and the abdomen is white. The sides of the body are light gray, and above the pectoral fins, they branch in two directions, one toward the dorsal fin and the other toward the back. The blackish gray line from the eye to the anus is characteristic of this species. The body is streamlined and somewhat thick. The boundary between the beak and the forehead is clear. The upper and lower jaws have 40 to 55 pairs of small conical teeth on each side. The forehead is rounded and bulges from the blowhole to the blowhole, and there is one blowhole. The dorsal fin is large, located in the center of the body, with a pointed tip and a sickle-shaped rear edge. The male's caudal peduncle has a pronounced keel (ridge-like protuberance) on the upper and lower sides. It usually lives in schools of 100 to 500 individuals, but sometimes schools of more than 1000 individuals can form. It mainly preys on pacific flying squids and lanternfish. It breeds in summer and winter. It is found in temperate to tropical waters of the entire ocean, with its northern limit at 50° north and its southern limit at 40° south. In purse seine fisheries operated in the tropical waters of the eastern Pacific Ocean, schools of yellowfin tuna swim along with schools of this species, so they are caught as bycatch and the current population is on the decline. In Japan, it is caught for food by chase fisheries and poke fisheries.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

クジラ目ハクジラ亜目マイルカ科スジイルカ属。体長は雄で約 2.6m，雌で約 2.5mに達する。最大体重は約 156kg。出生体長は約 1m。体色は背部が黒灰色で腹部は白色である。体側は淡灰色を呈し，胸鰭上方で，背鰭に向うものと背部後方へ向うものと2方向に分岐する。眼から肛門にかけての黒灰色の線が本種の特徴。体型は流線形でやや太い。嘴 (くちばし) と前頭部の境は明瞭。上下顎骨には左右 40～55対の小さい円錐形の歯がある。前頭部から噴気孔にかけて丸くふくらみ，噴気孔は1個。背鰭 (せびれ) は大きく，体の中央にあり先端はとがり後縁は鎌状である。雄の尾柄部は上下面のキール (稜状の隆起) が著しい。通常 100～500頭の群れで行動するが，ときには 1000頭をこえる群れをなすこともある。おもにスルメイカ類やハダカイワシ類などを捕食する。繁殖期は夏と冬。北緯 50゜を北限とし南緯 40゜を南限とする全海洋の温帯から熱帯海域に分布する。太平洋東部熱帯海域で操業される巾着網漁では，キハダの群れが本種の群れに付随して遊泳するため，混獲され現存数が減少傾向にある。日本では追込漁および突棒漁業により食用として捕獲されている。

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