The ears of otters protect from water via ear-flaps.

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References

"Among aquatic mammals such as the otter, the ear-flap can be pressed down to close the ear to water." (Foy and Oxford Scientific Films 1982:167)

Book
The grand design: Form and colour in animalsBLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, LondonAugust 25, 1983
Sally Foy

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Living System/s