Hippopotamus is a semi aquatic mammal belonging to the family Hippopotamus in the order Artiodactyla. Hippopotamus is the largest omnivorous mammal in freshwater, with a huge body size and short limbs; Thick and sturdy head; The mouth is large and can be opened at a 90 degree angle. The word hippopotamus means' horse in the river ', which is the Greek term for this powerful beast. They often live in groups, move around at night, soak in water most of the time, and have a gentle temperament. Hippos have a huge appetite, mainly feeding on aquatic plants such as reeds, and sometimes also on land crops such as green grass on the shore. It is a creature that has existed on Earth for a long time. They walked on Earth 55 million years ago.