Yes, dolphins are indeed warm-blooded animals.
Dolphins, whales, and porpoises are all warm-blooded marine mammals and belong to the cetacean family.
To help dolphins stay warm in cold environments, these marine mammals have developed a thick layer of fat which allows them to insulate and maintain their body heat while submerged in cold or freezing waters.
Interestingly, the thickness of a dolphin’s blubber only partially keeps these marine mammals warm.
For example, a high concentration of lipids combined with a low concentration of water in the dolphin’s blubber can help keep a dolphin warmer than another species with a thicker layer of fat but a low concentration of lipids.
In essence, the higher the lipid-to-water ratio in dolphin blubber, the better it will be at maintaining body heat in cold environments.
Depending on the species of cetacea, the amount of blubber they possess can range anywhere from 2 inches to over 1 ft thick.
However, unlike many of the larger whale species, most dolphin species are smaller overall and thus have much less blubber than their larger whale relatives, especially in baleen whales.
Because they possess less blubber, it is more common for dolphins to be found swimming in warmer climates in and around the equator as well as in some of the cooler regions of the world; large whales, on the other hand, may be found abundant in even the coldest climates near the northern and southern polar regions of the world.
Blubber can play a significant role in determining a dolphin’s habitat and range.
Dolphins that have less fat and a low lipid concentration may be limited to regions that are relatively warm or mild in temperature and may not be able to venture into the colder waters like a larger dolphin species such as the killer whale can do.
In addition to maintaining body heat through fat, dolphins can stay warm by increasing their metabolic rate.
This allows dolphins to burn calories which helps them transfer heat to their vital organs and muscles when they get cold.
And like humans and other land mammals, involuntary shivering may also help keep dolphins warm in colder climates, much like it helps keep humans stay warm by involuntarily increasing the movement of the muscles, which burn calories, prevents immobility, and produces heat.
Common Characteristics of Warm-Blooded Mammals
Being warm-blooded (cetaceans are warm-blooded marine mammals)
Giving birth (dolphins go through a pregnancy period and give birth just like humans and other mammals)
Having hair (some species are born with hair but lose it shortly after birth)
Producing milk (female dolphins feed their young a thick paste like milk from their nipples to provide their children with essential nutrients and fats so they can grow into healthy young adults)
Breathing oxygen (Just like land mammals, dolphins must get their oxygen above the surface of the water because they do not possess gills like fish, which would be necessary to extract oxygen directly from the water)