动物视觉 Vision in Animal Species

动物的眼睛随着时间的推移而进化，以满足每个物种特定栖息地的生存需求。每个物种的眼睛和它们产生的视觉都是独一无二的；对一种动物有效的视觉可能对另一种动物效果不佳。

Animal eyes have evolved over time to keep up with the demands of each species' particular habitat for survival. Eyes and the vision they produce are unique to each species; what works well for one animal may not work well for another.

只有少数物种能像人类一样感知世界，而其他物种则通过一只或多只眼睛以多色或黑色/白色来观察世界。

Only a few species perceive the world like humans do, whereas the others see it via one or many eyes and in multi colors or in black/white.

大多数物种依靠眼睛来感知光并将其转化为神经元中的电化学冲动。在有意识的视觉中，最简单的光感受器细胞可以将运动的物体与光联系起来。而对于具有更复杂视觉系统的生物体，它们可以从环境中收集光并通过可移动的透镜组件聚焦最后创建图像。之后图像会被转换成一系列电信号，并通过复杂的大脑网络发送到大脑。以下是一些视力最好和最差的生物。

The majority of species rely on eyes to sense light and translate it into electro-chemical impulses in neurons. In conscious vision, the simplest photoreceptor cells link movement to light. For organisms with more sophisticated vision systems, light gathered from the environment was focused through a movable lens assembly to create an image. After that, the image was converted into a series of electrical signals and sent to the brain via intricate cerebral networks. Here are some creatures with the finest and poorest vision.

猫头鹰无疑拥有森林中最清晰的夜视能力。 根据物种的不同，巨大的眼睛占猫头鹰体重的 1% 到 5%。 许多人都知道，朝前的眼睛具有“聪明的外观”，但更重要的是，它提供了广泛的“双眼”视觉，也就是睁着双眼观察物体的能力。

Owl has without a doubt the clearest night vision in the forest. Depending on the species, the huge eye accounts for one to five percent of the owls' body weight. Many individuals are aware that the eye that faces forward has a "smart appearance," but more importantly, it offers a wide range of "binocular" vision, which is the ability to perceive an object with both eyes open.

猫头鹰的视杆细胞数量较多，视锥细胞较少，因此以色觉作为交换，它们在没有光线的夜晚拥有敏锐的视力。

Owls have a higher number of rods and fewer cones, therefore in exchange for color vision, they have acute eyesight at night when there is no light.  

尽管夜视能力出色，但猫头鹰在强光下并非完全失明。 由于他们的瞳孔可以广泛调整，因此适量的光线可以照射到视网膜上。 在强光下，某些种类的猫头鹰甚至可以比人看得更清楚。

Despite having exceptional night vision, owls are not completely blind in bright light. Since their pupils may be adjusted widely, the proper amount of light can strike the retina. In bright light, certain owl species can actually see more clearly than people.

老鹰以其非凡的视力而闻名。 实际上，它们的视力都远高于其他动物。 在离地面650 英尺的高空飞行时，鹰能够看到 2 英里外的猎物和它们的运动轨迹。

Eagles are renowned for having extraordinary eyesight; practically all of them have visual acuity that is much above that of the other animals. While flying 650 feet above the ground, many are able to see their prey and identify the movements from a distance of 2 miles.

鹰的眼睛密密麻麻地布满了感觉细胞，这些细胞可以检测光线和图片，然后准备这些信息供鸟类的中枢神经系统进行解读。 平均而言，每平方毫米的视网膜中存在一百万个感光感觉细胞。 这是人类的五倍。接收到的图像最清晰的视网膜的两个中央凹、漏斗状区域。 两者都位于视网膜的中央区域。

An eagle's eyes are densely packed with sensory cells that detect light and pictures and then prepare this information for interpretation by the bird's central nervous system. On average, a million light-sensitive sensory cells are present in each square millimeter of the retina. This is five times what an ordinary human would have. The two fovea, funnel-shaped regions of the retina where received images are clearest. Both are situated in the retina's central region.

此外，第二个中央凹仅分析从鹰的视野外围到达的图片。 这有助于鹰更有效地处理侧视感官图像。

In addition, the second fovea only analyzes pictures arriving from the eagle's visual field's periphery. This helps the eagle process sideways-sight sensory pictures more effectively.

蝙蝠利用回声定位在黑暗中捕猎，这涉及利用它们自己的声音对其他事物的反射来引导它们。 与普遍的误解相反，蝙蝠并不是瞎子。 蝙蝠的眼睛可以适应低光照条件，以帮助它们更有效地寻找猎物，而且它们非凡的听力进一步提高了这种能力。

Bats utilize echolocation to hunt in the dark, which involves exploiting the reflections of their own sounds off other things to guide them. Bats are not blind, contrary to popular misconception. Although far from worthless, a bat's eyes are adjusted to low light levels to help them find prey more effectively, and their exceptional hearing power further improves this ability.

大约6亿年前寒武纪大爆发时，最早的物种就有了原始的眼睛。 视觉所需的分子器官存在于动物们的最后一个共同祖先中，之后的 96% 动物物种都拥有更复杂的眼睛。

When the Cambrian Explosion occurred approximately 600 million years ago, the earliest animal species had primitive eyes. The molecular apparatus required for vision was present in the last common ancestor of animals, and 96% of animal species have acquired more sophisticated eyes.

当光线进入大多数脊椎动物和一些软体动物的眼睛时，它会投射到视网膜上，视网膜是眼睛后部的一层感光细胞。 视网膜的视锥细胞和视杆细胞都能检测到光线并将其转化为用于视觉的大脑信号。 视杆细胞负责低光对比度，而视锥细胞分析颜色。 视神经然后将视觉冲动传递到大脑。虹膜周围的肌肉可以放松或收紧以改变瞳孔的大小，从而控制进入眼睛的光线量并减少在照明下的色差。

When light enters the eye of most vertebrates and some molluscs, it is projected onto the retina, a layer of photoreceptor cells at the back of the eye. The retina's cones and rods both detect light and turn it into brain signals that are used for vision. The rods held responsible for low-light contrast while cones analyze the color. The optic nerve then delivers visual impulses to the brain. The muscles around the iris can be relaxed or tightened to alter the pupil's size, which controls how much light enters the eye and lessens aberrations under excellent lighting.

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