Difference between a Dolphin and a Porpoise

Dolphins and porpoises have many things in common. They are both intelligent, playful sea animals and are known to help others outside of their own species. However, it’s common for most people to confuse one for the other. Let’s highlight the differences between the two.


Dolphin vs Porpoise
An Atlantic spotted dolphin

The dolphin belongs to a largely prevalent and diverse group of marine mammals in the order Cetacea (Greek word ketos, which means large sea creature). There are 4 existing families of dolphins: oceanic dolphins, Indian river dolphins, New World river dolphins and brackish dolphins. Killer whales belong to the oceanic dolphin family and are the largest of all. They can grow up to 31 feet (9.5 meters) and can weigh up to 10 tons (907 kilograms). The world’s smallest and rarest dolphin is Maui’s dolphin, with an average length of 1.7 meters (5.6 feet) long and average weight of 50 kilograms (110 lbs).

Dolphins have cone-shaped teeth used to catch fast-moving prey such as squid, fish, and even larger mammals including seals.

Dolphins are extremely social animals. They usually live in groups called pods, with members reaching up to 12 individual dolphins. Pod size and structure can vary depending on the species and location. There have been instances where pods merge temporarily to help each other catch food. These superpods can have more than 1,000 members all working towards the same goal.

A harbor porpoise. Note the short snout.

The porpoise is another group of marine mammals belonging to the family of toothed whales. Porpoises are sometimes called mereswine and are very close relatives of oceanic dolphins. Some distinct features of porpoises are its flat, spade-shaped teeth and shorter beak. Porpoises such as the vaquita can be as small as 1.4 meters (4.6 feet) and can weigh 54 kilograms (119 lbs). The biggest is Dall’s porpoise which is 2.3 meters (7.5 feet) long and weighs 220 kilograms (490 lbs).

Porpoises are fast swimmers, moving their tail fin together with their body in an up and down motion to propel themselves through the water. They porpoise out, or jump out, of the water to travel even faster. Triangular, well defined dorsal fins allow them to steer and turn in an instant.

Unlike their dolphin relatives, porpoises do not thrive in captivity. They are difficult to breed and just as hard to maintain. Some porpoises have been known to ram their heads into the container walls and floors. Some did not want to feed. However, some breeding establishments in Japan have had some levels of success with the finless porpoise.

Dolphin vs Porpoise

So what’s the difference between a dolphin and a porpoise? These two marine mammals are closely related and have much more in common than they do different.

Dolphins are bigger, with killer whales growing up to 31 feet (9.5 meters) long and weighing up to 10 tons (907 kilograms). The smallest porpoise ever discovered is the vaquita, measuring 1.4 meters (4.6 feet) long and weighing just 54 kilograms (119 lbs). Another major difference is their teeth – dolphins have conical teeth while porpoises have flat, spade-shaped teeth in a much smaller mouth. Want to be able to tell the difference just by looking at these two close relatives? Dolphins have a longer, more pointed snout than porpoises. Dolphins also have a curved dorsal fin, while porpoises have a more defined triangular fin.

Dolphins thrive well in captivity, unlike porpoises, who have a difficult time adjusting when taken out of their natural habitat. Dolphins are also known to be more social than their close cousins.

Comparison Chart

Dolphin Porpoise
Can grow up to 31 feet (9.5 meters) and weigh up to 10 tons (907 kilograms). Can grow up 2.3 meters (7.5 feet) long and weighs 220 kilograms (490 lbs).
Conical teeth set in a bigger mouth. Flat, spade-shaped teeth set in a smaller mouth.
Thrives well in captivity. Does not thrive well in captivity.
Curved dorsal fin. Defined, triangular dorsal fin.


Here’s short Youtube clip showing the difference between the two.