Hippos were once believed to be related to whales. They're both mammals, they both sleep underwater, and they both rise to breathe in their sleep, without waking.
From the Series: Aerial Africa: Zambia [ Ссылка ]
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Hippos were once believed to be related to whales. They're both mammals, they both sleep underwater, and they both rise to breathe in their sleep, without waking.
From the Series: Aerial Africa: Zambia [ Ссылка ]