Berardius bairdii; Baird's beaked whale

Japanese: ツチクジラ（英語表記）Berardius bairdii; Baird's beaked whale

It is a member of the order Cetacea, suborder Odontoceti, family Beaked whale, genus Baird's beaked whale. Males can reach a body length of about 11.9 meters, and females about 12.8 meters. They can weigh about 12 tons. They are the second largest toothed whales after the sperm whale. They reach a birth length of about 4.5 meters. Their body color is bluish gray all over, with a slightly paler abdomen. Some have white spots from the chest to the abdomen. Many bite marks are left on the surface of the body as white streaks. Their body is long and spindle-shaped, with a long beak and a protruding lower jaw. They have one blowhole located on the midline of the head, and the blowhole is a round, spray-like shape that rises to a height of about 2 meters. They have a V-shaped groove about 60 cm long in their throat. Their dorsal fin is small, located in the posterior two-thirds of their body, and is a right-angled triangle with a blunt tip. The caudal fin is large, about a quarter of the body length in width, with a slight notch in the center of the trailing edge. There are two pairs of teeth in the lower jaw, and the pair at the tip protrudes when the whaler reaches sexual maturity. They usually live in groups of 5 to 20 individuals, but sometimes they can form groups of 50 or more. Diving time is usually about 30 minutes, but occasionally exceeds 1 hour. The breeding season is thought to be from March to April. They mainly feed on deep-sea squids and bottom-dwelling fish, but also prey on sea cucumbers and snow crabs. They are limited to the North Pacific Ocean, and mainly live near the continental shelf slope and seamounts, or in the open ocean deeper than that. In Japan, about 150 to 250 whales are caught annually by small whaling, mainly in the Boso region on the Pacific coast.

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

Japanese:

クジラ目ハクジラ亜目アカボウクジラ科ツチクジラ属。体長は雄約 11.9m，雌約 12.8mに達する。体重は約 12tに達する。ハクジラ類ではマッコウクジラに次いで大きい。出生体長は 4.5m程度。体色は全身青みを帯びた灰色で腹部はやや薄い。胸部から腹部にかけて白斑をもつものがいる。咬傷が白色の筋となり体表に多く残る。体型は長い紡錘形で嘴 (くちばし) は長く下顎が突き出る。噴気孔は1個で頭部正中線上にあり，噴気は丸い飛沫状で高さ 2m程度上がる。咽喉部にハの字状の長さ約 60cmの溝がある。背鰭 (せびれ) は小さく，体の後方3分の2に位置し，直角三角形状で，その先端は鈍い。尾鰭は大きく，幅は体長の4分の1程度で後縁中央がわずかに切れ込む。下顎に2対の歯があり，先端にある1対の歯は性的成熟に達すると突出する。5～20頭の群れで行動することが多いが，50頭以上の群れをなすこともある。潜水時間は通常 30分程度であるがまれに1時間をこえる。繁殖期は3～4月と推測される。おもに深海性イカ類や底生魚類を食べるが，ナマコ，ズワイガニなども捕食する。分布は北太平洋に限られ，主として大陸棚斜面や海山近く，あるいはそれより深い外洋域に生息する。日本では小型捕鯨で太平洋岸の房総地方を中心に年間 150～250頭ほど捕獲されていた。

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