为什么鱼会长出鳞片，这是一个令人着迷的问题。鳞片是鱼类身体外部的保护层，能够提供力量和防御。在漫长的进化过程中，鱼类逐渐演化出了这样的特征，使它们能够生存于各种环境中。

At a cellular level, fish scales are composed of a tough protein called keratin. Keratin is the same protein found in our own hair and nails. It provides strength and flexibility to the scale, allowing it to withstand the pressures of swimming and protecting the fish from potential injuries. Interestingly, the arrangement and pattern of the scales differ among species, contributing to their distinctive appearance.

从细胞层面上看，鱼鳞由一种坚韧的蛋白质——角蛋白组成。角蛋白是我们自身头发和指甲中的蛋白质。它赋予鳞片强度和柔韧性，使其能够承受游泳带来的压力，并保护鱼类免受潜在伤害。有趣的是，不同物种的鳞片排列和图案各不相同，有助于它们具备与众不同的外观。

The evolutionary purpose of fish scales is multifaceted. Firstly, scales serve as a protective layer against predators. They act as armor, making it difficult for predators to penetrate the fish's body. Secondly, scales play a role in regulating water balance. Fish live in aquatic environments where osmotic balance is crucial for their survival. The presence of scales helps to prevent excessive water loss through their skin, maintaining optimal osmotic conditions.

鱼鳞的进化目的多方面。首先，鱼鳞作为一种保护层，起到了抵御捕食者的作用。它们就像盔甲一样，使捕食者难以侵入鱼的身体。其次，鳞片在调节水平衡方面发挥了作用。鱼类生活在水生环境中，渗透平衡对于它们的生存至关重要。鳞片的存在有助于防止皮肤过度失水，保持最佳的渗透条件。

Furthermore, scales aid in locomotion by reducing drag in the water. Fish scales are streamlined and reduce turbulence as the fish moves through water, allowing for efficient swimming. This advantage is particularly evident in fast-swimming fish species, such as tunas and swordfish, which have evolved sleek and smooth scales to optimize their movement through water.

此外，鳞片通过减少水中的阻力，有助于动物的运动。鱼鳞是流线型的，当鱼在水中游动时减少了湍流，使得游泳更加高效。这个优势在快速游泳的鱼类物种中尤为明显，比如金枪鱼和剑鱼，它们进化出了光滑的鳞片来优化其在水中的运动。

Interestingly, fish scales also play a role in thermoregulation. Some species of fish have special scales that possess heat-absorbing properties, allowing them to regulate their body temperature and adapt to varying environmental conditions. This adaptation is important for fish living in both cold and warm waters.

有趣的是，鱼鳞还在热量调节方面起到作用。一些鱼类拥有具有吸热特性的特殊鳞片，使它们能够调节体温，并适应不同环境条件。这种适应对于生活在寒冷和温暖水域的鱼类至关重要。

In conclusion, the development of scales in fish has been a remarkable adaptation in their evolutionary journey. These scales provide protection against predators, help regulate water balance, aid in efficient swimming, and even contribute to thermoregulation. The diversity and intricate design of fish scales continue to amaze scientists and inspire further research into the fascinating world of aquatic life.

总之，鱼类鳞片的发展在其进化历程中起到了显著的适应作用。这些鳞片提供了对抗捕食者的保护，帮助调节水平衡，有助于高效游泳，甚至参与温度调节。鱼类鳞片的多样性和精妙设计不断令科学家们惊叹，并激发了对水生生物世界更深入研究的兴趣。

Translation:

为什么鱼会长出鳞片 - Why do fish have scales

为什么鱼会长出鳞片，这是一个令人着迷的问题。- Why do fish have scales, this is a fascinating question.

At a cellular level, fish scales are composed of a tough protein called keratin. - 在细胞层面上，鱼鳞由一种坚韧的蛋白质——角蛋白组成。

The evolutionary purpose of fish scales is multifaceted. - 鱼鳞的进化目的多方面。

Furthermore, scales aid in locomotion by reducing drag in the water. - 此外，鳞片通过减少水中的阻力，有助于动物的运动。

Interestingly, fish scales also play a role in thermoregulation. - 有趣的是，鱼鳞还在热量调节方面起到作用。

In conclusion, the development of scales in fish has been a remarkable adaptation in their evolutionary journey. - 总之，鱼类鳞片的发展在其进化历程中起到了显著的适应作用。