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科学美国人60秒 SSS Brittle Stars Can "See" without Eyes

时间:2020-03-03 01:56:33

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(单词翻译)

The starfish relatives can recognize patterns using photoreceptors on their arms—and their color-changing abilities could have something to do with it. Christopher Intagliata reports.

Full Transcript 

Brittle1 stars are close relatives of starfish with a much more delicate appearance.

“So if you imagine a starfish with really skinny, spiny2 arms, made up of lots of little articulated plates, that’s kind of what a brittle star looks like—a cross between a millipede and a starfish, I guess.”

Lauren Sumner-Rooney is a visual ecologist at Oxford3 University. One of the brittle star species she studies, Ophiocoma wendtii, also has color-changing superpowers. 

“If you catch one of these animals during the day, they’re a really beautiful reddish brown, dark brown color. If you actually go out again at night and collect the same animal, they’re this very pale beige with dark stripes.”

The reason for that color shift was murky—perhaps for UV protection or camouflage4. But now Sumner-Rooney’s team has come up with a possible answer: that red coloration might help the brittle stars sort of see, even though they have no eyes. In bright daylight, their redness filters the light reaching photoreceptors along their arms.

Brittle stars like hiding in shady parts of the reef. So the researchers placed the brittle stars in an environment with black-and-white-patterned walls, aimed at testing whether the creatures were simply light sensitive—which isn’t the same as vision—or if they could truly see.

The vision test involved a black vertical5 bar centered on a white vertical bar twice the width. The nearby walls were 50 percent gray. Without true vision, the black-and-white-patterned area would simply come across as 50 percent gray, and you wouldn’t expect the brittle stars to consider that part of the arena6 a good hiding place.

Instead the brittle stars flocked towards the pattern—suggesting they have at least rudimentary visual skills. But strangely, the creatures lost this ability when they turned from red to beige. After doing digital reconstructions7 of the visual system, the researchers determined8 that perhaps the reddish pigments9 limit the angles of light reaching photoreceptors along the animals’ arms—thus improving the resolution of the brittle stars’ vision and allowing them to, in their own way, “see.”

The results are in the journal Current Biology. [Lauren Sumner-Rooney et al., Extraocular vision in a brittle star is mediated10 by chromatophore movement in response to ambient light]

So far, one species of sea urchin11 has also been shown to have this visual ability without true eyes, and it, too, changes color.

“There could be countless12 other examples of weird13 and wonderful visual systems that we have no idea are there—simply because, you know, this animal, looking at it, you can't find ‘an eye,’ a single discrete14 visual organ. And there are so many other animals like that that could be using vision, we just haven’t looked in the right place yet.”

In other words, when it comes to seeing, the eyes don’t always have it.

—Christopher Intagliata 


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1 brittle IWizN     
adj.易碎的;脆弱的;冷淡的;(声音)尖利的
参考例句:
  • The pond was covered in a brittle layer of ice.池塘覆盖了一层易碎的冰。
  • She gave a brittle laugh.她冷淡地笑了笑。
2 spiny 3F9zU     
adj.多刺的,刺状的;n.多刺的东西
参考例句:
  • This is the Asiatic ornamental shrub with spiny branches and pink blossoms.这就是亚洲的一种观赏灌木,具有多刺的枝和粉红色的花。
  • Stay away from a spiny cactus.远离多刺仙人掌。
3 Oxford Wmmz0a     
n.牛津(英国城市)
参考例句:
  • At present he has become a Professor of Chemistry at Oxford.他现在已是牛津大学的化学教授了。
  • This is where the road to Oxford joins the road to London.这是去牛津的路与去伦敦的路的汇合处。
4 camouflage NsnzR     
n./v.掩饰,伪装
参考例句:
  • The white fur of the polar bear is a natural camouflage.北极熊身上的白色的浓密软毛是一种天然的伪装。
  • The animal's markings provide effective camouflage.这种动物身上的斑纹是很有效的伪装。
5 vertical ZiywU     
adj.垂直的,顶点的,纵向的;n.垂直物,垂直的位置
参考例句:
  • The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
  • Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。
6 arena Yv4zd     
n.竞技场,运动场所;竞争场所,舞台
参考例句:
  • She entered the political arena at the age of 25. 她25岁进入政界。
  • He had not an adequate arena for the exercise of his talents.他没有充分发挥其才能的场所。
7 reconstructions b68a36323018dfe7d6624e864a340794     
重建( reconstruction的名词复数 ); 再现; 重建物; 复原物
参考例句:
  • Multicolored reconstructions have been formed using (black and white) volume holographic plates. 利用黑白体积全息片已经做成了彩色重建象。
  • The method gives ways to evaluate collision speed in traffic accident reconstructions. 该模型为交通事故再现推算碰撞速度提供了有效实用的方法。
8 determined duszmP     
adj.坚定的;有决心的
参考例句:
  • I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
  • He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
9 pigments 90c719a2ef7a786d9af119297e63a36f     
n.(粉状)颜料( pigment的名词复数 );天然色素
参考例句:
  • The Romans used natural pigments on their fabrics and walls. 古罗马人在织物和墙壁上使用天然颜料。 来自辞典例句
  • The original white lead pigments have oxidized and turned black. 最初的白色铅质颜料氧化后变成了黑色。 来自辞典例句
10 mediated b901b5da5d438661bcf0228b9947a320     
调停,调解,斡旋( mediate的过去式和过去分词 ); 居间促成; 影响…的发生; 使…可能发生
参考例句:
  • He mediated in the quarrel between the two boys. 他调解两个孩子之间的争吵。
  • The government mediated between the workers and the employers. 政府在工人与雇主间搞调和。
11 urchin 0j8wS     
n.顽童;海胆
参考例句:
  • You should sheer off the urchin.你应该躲避这顽童。
  • He is a most wicked urchin.他是个非常调皮的顽童。
12 countless 7vqz9L     
adj.无数的,多得不计其数的
参考例句:
  • In the war countless innocent people lost their lives.在这场战争中无数无辜的人丧失了性命。
  • I've told you countless times.我已经告诉你无数遍了。
13 weird bghw8     
adj.古怪的,离奇的;怪诞的,神秘而可怕的
参考例句:
  • From his weird behaviour,he seems a bit of an oddity.从他不寻常的行为看来,他好像有点怪。
  • His weird clothes really gas me.他的怪衣裳简直笑死人。
14 discrete 1Z5zn     
adj.个别的,分离的,不连续的
参考例句:
  • The picture consists of a lot of discrete spots of colour.这幅画由许多不相连的色点组成。
  • Most staple fibers are discrete,individual entities.大多数短纤维是不联系的单独实体。

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