The name “dolphin” is borrowed from the Greek word “delphis” which is related to another Greek word “delphus”, which means “uterus”. Therefore, the name can be interpreted as “a fish with womb”.
Dolphins are aquatic animals from the order of “Cetaceans”. Although widespread, most dolphins prefer warm water from tropical areas. They feed mainly on small fish, but some can feed on large mammals like a seal.
In countries like Japan, dolphins are hunted in an activity known as dolphin hunting. Other threats to dolphins include habitat loss, marine pollution, and accidental catches.
Even though dolphins live in the water almost all the time, they are neither fish nor cold-blooded creatures, they are mammals. Dolphins should not be confused with the mahi-mahi, which is a common type of surface fish.
Dolphins are warm-blooded, just like other mammals, and unlike fish that breathe through gills, they use their lungs. Dolphins cannot breathe in the water because they’d drown; rather, they frequent the surface of the water to breathe. On the other hand, the fish will suffocate above the surface of the water because gills are not designed to breathe on the surface.
Unlike fish, they possess vertebrae. Dolphins are believed to have evolved from land-dwelling mammals from the order of “Artiodactyls”, with the closest living relative being the hippo.
The size of a dolphin varies from 5.6 feet to 31 feet and the average weight is about 110 pounds. The body is torpedoed with a non-flexible neck. The limbs have been modified into flippers.
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The skull has the orbit of small eyes, with eyes placed on the edge of the head. The teeth are conical in shape and are useful in catching prey quickly.
Dolphins possess a thick layer of blubber that helps buoyancy and protects them from predators and energy loss. The primary use of blubber is to isolate the dolphin from the harsh climate.
Apart from being a warm-blooded mammal that breathes through the lungs, several other features make it more mammal than fish.
Female dolphins give birth to live offspring, not by laying eggs like fish. The reproductive organs of dolphins are located in ther lower parts. Copulation occurs in the belly.
The gestation period varies from 11 to 12 months. Females only mate every two years, and males can mate with several females within a year. Females also possess mammary glands that are only present in mammals and feed their offspring with milk.
Dolphins give birth to their young ones on the surface of the water. The period of pregnancy in females lasts between 10 and 18 months. During birth, other dolphins protect the birth from shark attacks. After birth, the newborn dolphin reaches about 50 cm in length. When a dolphin is born, the tail is the first to come out. After birth, the mother immediately lifts the newborn baby into the air so that the new dolphin takes its first breath. The mother stays next to the baby for about three years. At the same time, in the first year of life, the baby dolphin feeds on its mother’s milk.
Scientific studies have shown that in the first month of life, the newborn dolphin does not sleep. Mother dolphin in the first months constantly protects its baby and also is forced not to sleep during the first month of her baby’s life. The estimated life span of dolphins is around 20-30 years.
Also, like most mammals, dolphins have small layers of hair around the blowhole. A blowhole is a characteristic of dolphins that facilitates breathing. Unlike humans, dolphins do not breathe through the mouth, but through the hole. Blowhole ensures that water does not enter the lungs if it accidentally inhales it while swallowing prey underwater.
Dolphins differ from fish in many ways. Both dolphins and fish have adapted to live their entire lives in the water, both of which have aerodynamic bodies and swimmers. But dolphins are mammals and therefore have to regularly go on the surface to breathe air to survive. Otherwise, they would drown. Fish extract oxygen from the water and do not need to surface.
Dolphins’ tails move up and down as they swim, while fish tails move from side to side.
Dolphins have warm blood and fat to keep them warm. Fish are cold-blooded and are able to adapt to different water temperatures without needing body fat to maintain their heat.
It is known that most fish lay eggs and can lay hundreds of eggs in a single year. Dolphins give birth to a single baby once every 1 to 6 years and then feed their young with milk through their nipples.
Yes, a dolphin is a mammal, and here’s why: