What kind of animal is a dolphin, how does it breathe, and what is the function of its tail?
Dolphins are very adorable marine creatures. Every time we visit an aquarium, they are extremely popular and can perform many tricks. Dolphins are very attuned to human nature, and there are many news reports of dolphins rescuing humans at sea. The dolphin's body shape is streamlined, with a pointed snout and pleasant vocalizations. Let's take a look below at what type of animal a dolphin is, how it breathes, and what the function of its tail is.
I. What type of animal is a dolphin?
Dolphins are aquatic mammals of the cetacean order, mostly small toothed whales, distributed in oceans, inland seas, and the brackish water at river estuaries around the world, with a few also found in inland rivers.
Dolphins have a history of more than 20 million years. They are extremely agile and are the fastest-swimming mammals in the water. Their hearing is excellent, both in water and in air. Dolphins have very high intelligence and are lively, gentle, and friendly in temperament, deeply loved by everyone.
II. How do dolphins breathe?
The vast majority of fish in the sea breathe through gills. Is the dolphin the same? Dolphins are similar to us humans: they breathe through their lungs via the mouth and nose. Their nostrils are on top of their heads, so they must frequently surface to breathe at the sea surface.
III. What is the function of a dolphin's tail?
A dolphin's tail is the main organ that propels it forward and enables it to change direction while swimming, and it is also the key tool that allows it to maintain rapid swimming. Dolphins swim swiftly, usually at a top speed of around 30-40 km per hour; some species can exceed 55 km/h and sustain it for a long time, making them the long-distance swimming champions of the ocean.
The dolphin's swimming style is very unique and differs from that of other whales: the entire body leaps out of the water at a shallow angle and re-enters at a shallow angle. The familiar flutter kick in butterfly stroke also has a common nickname, the dolphin kick, because this kicking motion closely resembles the way a dolphin's tail moves.
At present, all genera and species in the family Delphinidae are listed in China's "List of National Key Protected Wild Animals," among which the Chinese white dolphin (Sousa chinensis) is a national first-class protected animal, and other dolphins are national second-class protected animals. This is because about one quarter of extant whales and dolphins are under varying degrees of threat to their survival. Take large-scale human hunting, for example: although people are fishing, there are still times when dolphins are caught accidentally and end up as food on people's plates. Others are caught and placed in artificial aquarium environments, which shortens dolphins' lifespans, because dolphins are prone to illness in water with excessive chlorine.
Global warming is now causing sea levels to rise and triggering changes in the ecological environment such as precipitation, water temperature, and salinity, making it impossible for dolphins to adapt to their surroundings for a time, threatening their lives. Various engineering projects built by humans also block dolphins' migration and other activities.