Jellyfish are the oldest animals in the ocean—they’ve been swimming on our planet for more than half a billion years. But it is only recently that scientists have begun to understand these beautiful but deadly organisms, from the sophisticated way they propel themselves to the complex chemistry involved in their phosphorescent glow. The picture that emerges, according to Juli Berwald, author of the new book Spineless, is of an “incredibly well-adapted, super-elegant creature.”

Speaking from her home in Austin, Texas, Berwald, who has written for National Geographic, explains how the jellyfish’s glow revolutionized genetics; why robots are copying jellyfish; and how jellyfish are taking advantage of ocean acidification to expand their range and invade new waters.

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