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Turtle Neck Retraction |
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| Scientists recognize two categories of turtles and tortoises—hidden-necked and side-necked. Hidden-necked species pull their heads directly backwards so that the neck vertebrae curve into a U-shape, as shown on the bottom left. In contrast, side-necked turtles, shown on the right, snake their neck sideways to tuck their head under the shell. | ||||||
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