Jellyfish as a species are actually older than dinosaurs and sharks.
383
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Cymothoa exigua is a type of parasite that enters through fish's gills, eats their tongue, and then replaces it.
6
Nervous dogs wag their tails to the left, and happy dogs to the right (from the dog’s point of view) – and fellow canines pick up on this lop-sided tail language.
10
The most expensive dog in the world is the Tibetan Mastiff; worth $1.5 million.
2