Scientists Discover How a Kind of Fish Makes Colorful Light Appear

The skin of a small fish from Thailand is almost completely clear. But when light shines through it, a shimmering² rainbow of colors appear.

Now, scientists have found out how this fish — called the ghost catfish³ — creates colorful light that is iridescent⁴. Something iridescent shines with many different colors depending on how you look at it.

That color comes from within the fish's body. Researchers reported their findings in a study published recently in Proceedings⁵ of the National Academy of Sciences. As light passes through the fish's skin, it hits very small structures in the muscle that turn light into a colorful spectrum⁶.

The ghost catfish, which is sometimes called the glass catfish, is a small fish native to rivers in Thailand. It averages just a few centimeters long. It is sold around the world as an aquarium⁷ fish.

Other creatures are also iridescent, creating the rainbow effect when colors change when looked at from different sides. Usually, they have outer surfaces that reflect the light, like a hummingbird's feathers or a butterfly's wings, said Ron Rutowski. He is a biologist at Arizona State University who was not involved with the research.

The ghost catfish have no scales, said writer Qibin Zhao. He is a physicist⁸ at China's Shanghai Jiao Tong University. Zhao became very interested in the fish after seeing it in an aquarium store.

Instead, it has structures in its muscles. These are what turns light into rainbow colors. Researchers made the discovery after shining different kinds of light and lasers onto the fish in a laboratory. As the ghost catfish swims, its muscles move, resulting in reflections of many colors.

The fish's clear skin lets in around 90 percent of outside light.

"We wouldn't be able to see the colors if the skin of the fish is not so transparent⁹," Zhao said in an email.

Some species use their iridescence¹⁰ to attract mates or give off warning signals. It is not clear whether the ghost catfish's colors serve a purpose, Rutowski said.

Words in This Story

shimmer¹ — v. to shine with a light that appears to move around

iridescent –adj. shining with many colors when seen from different directions

spectrum –n. a group of colors that appear when white light is separated by glass or a similar material

aquarium — n. a glass tank that holds fish or similar animals that people keep for recreation

reflect — v. to move light in a direction other than the one it is traveling in

scale –n. small, hard structures that cover the body of most fish, reptiles¹¹, and some other animals

transparent — adj. able to be seen through

1 shimmer   

v./n.发微光，发闪光；微光

参考例句：

• The room was dark,but there was a shimmer of moonlight at the window.屋子里很黑，但靠近窗户的地方有点微光。
• Nor is there anything more virginal than the shimmer of young foliage.没有什么比新叶的微光更纯洁无瑕了。

2 shimmering   

v.闪闪发光，发微光( shimmer的现在分词 )

参考例句：

• The sea was shimmering in the sunlight. 阳光下海水波光闪烁。
• The colours are delicate and shimmering. 这些颜色柔和且闪烁微光。 来自辞典例句

3 catfish   

n.鲶鱼

参考例句：

• Huge catfish are skinned and dressed by hand.用手剥去巨鲇的皮并剖洗干净。
• We gigged for catfish off the pier.我们在码头以鱼叉叉鲶鱼。

4 iridescent   

adj.彩虹色的，闪色的

参考例句：

• The iridescent bubbles were beautiful.这些闪着彩虹般颜色的大气泡很美。
• Male peacocks display their iridescent feathers for prospective female mates.雄性孔雀为了吸引雌性伴侣而展现了他们彩虹色的羽毛。

5 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

6 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

7 aquarium   

n.水族馆，养鱼池，玻璃缸

参考例句：

• The first time I saw seals was in an aquarium.我第一次看见海豹是在水族馆里。
• I'm going to the aquarium with my parents this Sunday.这个星期天，我要和父母一起到水族馆去。

8 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

9 transparent   

adj.明显的，无疑的；透明的

参考例句：

• The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到鱼儿游来游去。
• The window glass is transparent.窗玻璃是透明的。

10 iridescence   

n.彩虹色；放光彩；晕色；晕彩

参考例句：

• You can see the iridescence on their faces. 你可以看到他们脸上的彩虹色。 来自辞典例句
• The huge pool of blood in front of her was already assuming the iridescence of coagulation. 她面前那一滩血，已经凝结了起来，显出五光十色。 来自辞典例句

11 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》