The Lion's Mane Jellyfish is the largest jellyfish in the world. They have been swimming in arctic waters since before the dinosaurs (over 650 million years ago).
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A koi fish, named "Hanako", was owned by several individuals over many years and lived to be 226 years old, dying in 1977.
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Parrot parents "name" their children with a signature call.
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The male seahorse carries babies and 'gives birth' to them instead of the female.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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There is a sea snail that wears a suit of iron plated armor. It is the only known animal to use iron sulphide as skeletal material.
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