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Photographs: © Stephen Dalton/NHPA/Photoshot (axolotl); Kjell B. Sandved/Photo Researchers, Inc. (sea cucumber); © Gary Bell/Corbis (sea star); Tom Adams/Visuals Unlimited, Inc. (planaria); Chris Newbert/Minden Pictures/National Geographic Stock (sea squirts, lobster); Michael & Patricia Fogden/Minden Pictures/National Geographic Stock (tadpoles); © Beverly Speed/Shutterstock (nudibranch); © Wave Royalty Free/Age Fotostock (salmon)
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