Source：科學60秒
Date：200907.10
Summary
《科學》雜誌上的一項研究追蹤了海龜殼的胚胎髮育過程，包括肩胛骨在肋骨內的摺疊。A study in the journal Science tracks the embryonic development of the turtle's shell, which includes the shoulder blades getting folded within the ribs.
Shell Shock: Turtle Development Secret Revealed
It sounds like the title to a Rudyard Kipling tale: how the turtle got its shell. But it’s actually a question that has puzzled scientists. After all, no other animal, living or extinct, has a similarly constructed bony shield surrounding its body. Scientists had thought that, over evolutionary time, small bony plates fused with the animal’s skin. But a new study published July 10th in the journal Science offers a different pathway.In most animals the shoulder blades lie outside the ribs. Not so with turtles. And there’s no intermediate evolutionary form in which the shoulder blades lie beneath ribs. So researchers in Japan compared chicken, mouse and Chinese soft-shelled turtle embryos at different stages of development. They show that initially the embryos develop along the same pathways. But the turtle takes a turn.As it develops, part of its body folds in on itself. Shoulder blades get folded within the ribs. The ribs stay connected, but new connections also develop between bone and muscles. Then the shell starts to develop as the ribs fuse together and encase the shoulder blades. Not as droll perhaps as a “Just So” story. But more fascinating for being true.
Audio
Words
embryonic：[ˌembriˈɒnɪk] 胚芽的，胎兒的，初期的
fold：[fəʊld] 摺疊，合攏
Rudyard Kipling：魯德亞德·吉卜林，英國著名小說家、詩人
pathway： [ˈpɑ:θweɪ] 路，道，途徑，路徑
intermediate： [ˌɪntəˈmi:diət] 中間的，中級的中間物，中間分子，中間人.調解
Chinese soft-shelled turtle：中華鱉
embryo： [ˈembriəʊ] 胚芽，胚，胚胎，初期
encase：[ɪnˈkeɪs] 包裝，圍繞，把…裝箱
Website address
https://www.scientificamerican.com/podcast/episode/shell-shock-turtle-development-secr-09-07-10/
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