Marine mammals of the order Cetiformes and family Sperm Whales. With a body length of up to 18 meters and a weight of over 50 tons, it is the largest toothed whale and the deepest and longest diving mammal. Like a fish in size, it breathes through its lungs. Sperm whales prefer to live in groups, often consisting of a small number of male whales and large groups of female and juvenile whales forming large groups of dozens or even two to three hundred. Sexually fierce. The marriage system of one male and multiple females. The geographical range of distribution is very wide. But it is usually found in the continental slope or deeper waters. The dried secretion of sperm whale intestines is called "ambergris", which is not only a precious spice but also a precious traditional Chinese medicine.

Hippopotamus is a semi aquatic mammal belonging to the family Hippopotamus in the order Artiodactyla. Hippopotamus is the largest omnivorous mammal in freshwater. The word hippopotamus means' horse in the river ', which is the Greek term for this powerful beast. Hippos are mainly distributed in tropical regions of Africa, inhabiting swamps and reed beds near rivers. Hippopotamuses often live in groups, move around at night, and spend most of their time soaking in water. They 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. The high value of hippopotamus's long teeth is one of the reasons for their rapid decline.