1. Dolphins (scientific name: Delphinidae) are aquatic mammals closely related to whales and porpoises. They evolved in the Miocene about 10 million years ago and live widely in shallow seas near the continental shelf. , occasionally found in fresh water. The length of various dolphins ranges from 1.2 meters to 9.5 meters, and the weight ranges from 40 kilograms to 10 tons. They mainly feed on fish and molluscs. There are 18 species of dolphins known to exist off the coast of China. Dolphins, with their friendly-looking appearance and playful personalities, have always been very popular in human culture.

2. Pufferfish is a collective name for animals in the class Mammalia, order Cetaceans, and the superfamily freshwater dolphins. The superfamily Platanistoidea has four living species that inhabit freshwater rivers and estuaries: three of them live in freshwater rivers; and the other species, the Plata river dolphin (La river dolphin), lives in saltwater estuaries and estuaries. In coastal marine waters, however, it is still classified in the scientific classification of the freshwater dolphin superfamily rather than the family Delphinidae. Some dolphins can survive in both ocean and river environments. For example, the Amazon white dolphin (commonly known as the "Turkish dolphin") can adapt to both ecological environments. However, these dolphins are not included in the superfamily Freshwater Dolphins and are not considered true freshwater dolphins. Young freshwater dolphins are gray in color and turn pink when mature. Freshwater dolphins are the most human-friendly mammals among mammals, and they are adorable.

Special note: Pufferfish is a mammal and non-venomous; for a fish with the same sound as it that is poisonous, see "Pufferfish".