Flight - Hishou (English spelling) flight

Japanese: 飛翔 - ひしょう（英語表記）flight

When animals fly in the air. The first animals to fly were insects similar to large cockroaches in the Mesozoic era about 200 million years ago. Among vertebrates, reptiles such as pterosaurs are known. Among modern animals, most birds, some mammals such as bats, and most insects skillfully flap their wings and fly. Some fish such as flying fish, mammals such as flying squirrels, and amphibians such as flying frogs do not have wings, but are known to glide using fins or membranes.
There are two basic types of flight: winged flight, which uses kinetic energy, and gliding, which uses potential energy. In order for warm-blooded animals (birds and bats) to be able to fly by flapping their wings, various changes to the structure of their bodies were necessary during the course of evolution. For example, in birds, a pair of forelimbs was transformed into wings. Their bones became hollow to reduce weight, and the skeleton of their torso was fused to become box-shaped, allowing them to use the power of flapping more effectively. They succeeded in reducing the weight of their internal organs, such as omitting the large intestine by excreting food immediately and shrinking their reproductive organs during non-breeding seasons. In terms of the center of gravity, the teeth and jaw muscles were replaced by a beak, and the head became lighter, improving stability. In addition, the relatively heavy digestive organs were placed at the base of the wings and legs, solving the misalignment of the center of gravity during flight and walking. In addition, changes occurred in all aspects, such as the strengthening of the heart and chest muscles that generate the power of flapping, and the development of vision and hearing to fly safely. On the other hand, insects developed wings, but these were not a result of the modification of legs, but rather a specialization of the keratin that covers the entire surface of the body. The benefits to these flapping flying animals were great, because when we consider the number of species and the number of individuals, insects, birds, and bats are the most prosperous animal groups.
There are two types of gliding: gravity gliding and soaring. Gravity gliding can be divided into two types: gliding where the animal takes off in a set direction, and passive gliding where the animal slowly descends horizontally, relying on the wind. Many animals that perform gravity gliding, which determines their direction, have special organs in various parts of their body that act as wings. For example, the flying fish has a large pectoral fin, the flying frog has a large water paw, the flying lizard has a stretchable membrane on its side, and the flying lemur, Japanese flying squirrel, and Japanese flying squirrel have developed membranes between their front and back legs. The flying lizard can glide about 60 meters, and the flying lemur can glide more than 130 meters, with the tail and limbs acting as rudders. Soaring is staying in the air for a long period of time without flapping its wings. Large birds such as condors and albatrosses and insects such as monarch butterflies have mastered this technique. When the wind is blowing uniformly, animals that attempt soaring need to catch air currents with an upward velocity that exceeds their own sinking velocity. Conditions suitable for soaring are near mountains or seaside cliffs where the wind's path is blocked and updrafts are created, and when the earth is warmed by sunlight and heat circulates in the atmosphere. Birds can also obtain energy for flight from small disturbances in the air. Albatrosses weigh about 7 kg, but with their huge wingspan of about 2.4 m, they can catch the gradient of wind speed near the sea surface and soar for considerable distances by repeatedly ascending and descending while making successive turns.

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

Japanese:

動物が大気中を飛ぶこと。動物が初めて飛翔したのは約2億年前の中世代のことで，ゴキブリを大きくしたような昆虫と考えられている。脊椎動物では，翼竜のような爬虫類が知られている。現生の動物では鳥類のほとんど，コウモリなどの哺乳類の一部，昆虫類の大部分が翼や翅を使って巧みにはばたき，飛翔する。またトビウオなどの一部魚類，哺乳類のムササビや両生類のトビガエルなどは翼をもたないが，鰭や皮膜を使って滑空することが知られている。
飛翔には基本的に運動のエネルギーによるはばたき飛行 winged flightと，位置のエネルギーによる滑空 glidingの2種類がある。定温動物 (鳥類とコウモリ) がはばたき飛行をするためには，進化の過程で体の構造をさまざまに変化させる必要があった。鳥類を例にとれば，一対の前肢が翼に変形した。骨は中空になって軽量化するとともに，胴部の骨格が融合して箱型になり，はばたきの力を有効に使えるようになった。食べた物をすぐに排泄することで大腸を省略し，生殖器官も非繁殖期には縮小するなど，内臓の減量化に成功している。重心の面では，歯や顎の筋肉は嘴に置換され，頭部が軽くなったので安定が良くなった。また比較的重い消化器官を翼と脚の付根にくるように配置し，飛翔と歩行時の重心のずれを解決している。さらに，はばたきの力を生みだす心臓と胸筋の強化，安全に飛翔するための視覚や聴覚の発達などあらゆる面で変化が起った。一方，昆虫では翅が発達したが，これは肢が変化したものではなく，体表全体をおおっている角質が特殊化したものである。これらのはばたき飛翔する動物にもたらされた恩恵は大きい。種の多さや個体数の多さを考えてみると，昆虫，鳥類，コウモリは最も繁栄した動物グループといえるからである。
滑空には，いわゆる重力による滑空とソアリング (帆翔あるいは滑翔。 soaring) の2種類がある。さらに重力による滑空には，方向を定めて飛立つものと，水平の動きは風にまかせてゆっくり降下する受動的なものがある。方向を定める重力滑空を行う動物には，体のさまざまな部位に，翼の代りとなる特殊な器官を備えたものが多い。例えば，魚類では胸鰭を大きく発達させたトビウオ，両生類では大きな蹼 (みずかき) をもつトビガエル，爬虫類では伸縮自在の皮膜を体側にもつトビトカゲ，哺乳類では前肢と後肢の間に皮膜を発達させたヒヨケザルやムササビ，モモンガなどである。トビトカゲで約 60m，ヒヨケザルで 130m以上滑空できるといい，尾や手足が方向舵の役目をしている。ソアリングは長時間はばたかずに滞空することである。コンドルやアホウドリなどの大型の鳥とオオカバマダラなどの昆虫が，この方法を獲得した。風が一様に吹いているときにソアリングを試みる動物に必要なのは，自分の沈下速度を超える上昇速度をもつ気流を捉えることである。風の進路が妨げられて上昇気流が生れる山脈や海辺の崖縁付近，また太陽光によって大地が暖められ，大気中に熱の循環が起るときがソアリングに適した条件といえる。また大気中の小さな気流の乱れからも，鳥たちは飛翔のエネルギーを得ることができる。アホウドリの体重は約 7kgに達するが，翼開長約 2.4mという巨大な翼で海面近くの風速の勾配をとらえ，次々と旋回しながら上昇と降下を繰り返すことで，かなりの距離を滑翔することができる。

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