Dolphins and porpoises are cetaceans, marine mammals closely cousins with whales.
Dolphins are a member of the Delphinidae family and are as big as 30 feet long.
Porpoises, belonging to the Phocoenidae family, are stout and smaller, with other anatomical differences.
Even though both animals are extremely intelligent, dolphins are considered more social and live in larger, more stable groups.
Although “porpoise” and “dolphin” are often used interchangeably.
The term porpoise should be used only for the Phocoenidae family, which has seven porpoise species.
Dolphins are more common than porpoises. Most scientists have agreed that there are 32 dolphin species (plus five closely related species of the river dolphin) and only about six porpoise species.
Difference Between Dolphins and Porpoises
The difference between dolphins and porpoises essentially comes down to their facial structure ( I mean, no person can easily forget Flipper’s famous “grin”), figures, and fins.
Dolphins are known to have elongated prominent beaks, as well as cone-shaped teeth. On the other hand, porpoises have smaller mouths and teeth shaped like a spade.
The dolphins have a hooked or curved dorsal fin (which is the one located in the middle of the animal’s back), but the porpoise has a triangular dorsal fin. Generally, we can say that the dolphin bodies are leaner, while the porpoises’ are portly.
Another interesting difference is that dolphins are known to be more vocal than porpoises. Dolphins are very interactive as they make whistling sounds via their blowholes to communicate with one another underwater.
Scientists are almost certain that porpoises do not make this communication pattern, and some assume that this may result from structural differences in the porpoise’s blowhole.
Dolphins and porpoises also have many similarities, including their outstanding intelligence.
Both animals have large and complex brains. They also boast of a structure in their foreheads, known as the melon, with which they can generate sonar (sound waves), which helps them to navigate their underwater world.
Dolphin vs. Porpoise Anatomy
The main difference between porpoises and dolphins is anatomical, as mentioned earlier. Externally, anyone can tell the difference between both animals by looking at the head and dorsal fins.
Dolphins normally have a “beak” that makes them appear “long-nosed,” while porpoises do not have a beak and thus appear more “flat-faced.”
The dorsal fins on dolphins are usually curved or hooked, while those on porpoises are more triangular.
Up close, one can distinguish the two by their teeth: dolphins have cone-shaped teeth, but porpoises have flat or spade-shaped teeth.
Dolphins and porpoises come in varying sizes, with dolphins generally appearing larger than both aquatic animals.
The killer “whale” or orca, which is a dolphin, genetically, can grow to sizes of up to 35 feet in length, for instance, and Hector’s dolphin, which is found in New Zealand, sometimes grows bigger than 4 feet. On average, porpoises, which appear more darkly colored than dolphins, grow to between 5 and 8 feet in length.
Both mammals breathe air via the blowholes at the top of their head. And, like almost all other mammals, these two animals give birth to their young lives and nurse their offspring.
Porpoises and dolphins even have hair, but almost all of it is lost shortly after birth.
Of the three fin types found on porpoises and dolphins, only the flippers (pectoral fins), which function as tools for stopping and steering underwater, have bones.
These unique fins contain the same number of bones that are contained in a human arm and also end in five digits that are aligned similarly to fingers. Scientists have theorized that these bones evolved from the ancient land-dwelling ancestors of dolphins and porpoises some 50 million years ago.
Beyond the dorsal, the pectoral fins or back provide stability as the porpoise and dolphin move swiftly through water (up to 25 mph).
This dorsal fin and the tail flukes are made of pure collagen, a fibrous connective tissue similar to cartilage.
The use of Echolocation and Other Senses
Both porpoises and dolphins use echolocation to find food, navigate underwater, avoid predators, and communicate with other species.
They also have a small external ear opening about two inches behind the eye in the porpoise and dolphin. Neither porpoises nor dolphins rely specifically on their sense of smell.
However, vocalizations are more frequent and extensive with dolphins, and these sounds can travel longer distances than those recorded for porpoises.
Reproduction
Males of both porpoises and dolphins feature two genital openings on their ventral side, while the females have four.
Two out of the female’s four openings are their sex organs, and the other two are for lactation, with their teats located inside the body.
The mating seasons for porpoises and dolphins tend to be short, with the dominant males having multiple mates. Pair bonding is not common in porpoises but is more frequently observed in dolphins, and this union is often one that lasts for life.
Gestation periods for both animals are very similar, lasting between 7 and 12 months, with the birth of 1-2 calves, though the births are most often single. Calves for both dolphins and porpoises are weaned after about a year.
Social Behavior of Dolphins and Porpoises
Dolphins have been found to live in pods or small groups of up to 12 individuals. Where food is abundant. However, “superpods,” a collection of over 1,000 dolphins, have been noticed.
Dolphins carry out hunts and communicate for other reasons by combining clicks, whistles, and ultrasonic sounds.
Porpoises are relatively shy animals and are seen roaming alone or in small groups containing a few individuals.
It is quite rare to find them in large pods. Their grouping behavior also does not lead to any stable associations, but there are ephemeral relationships that will change as individuals leave or join.
Porpoises can function in a coordinated fashion even in cases where they are hundreds of feet away from each other, using echolocation for locating prey and staying together in the same pod, but do not use echolocation to communicate as often as their dolphin cousins do.
Dolphin vs. Porpoise Intelligence
Dolphins and porpoises are both highly intelligent mammals. They have large and complex brains, and both animals are self-aware, just like humans.
These animals are among the few species in the waters and the world to identify themselves in a mirror.
Several years of research have allowed scientists to make an extensive case for protecting cetaceans (including dolphins, porpoises, and whales) from unrestricted hunts and fishing.
This and the risk of potential extinction are a few of the reasons for international bans on dolphin and whale hunting, as well as the prohibition of net-based tuna fishing, which could lead to the trapping and drowning of dolphins.
The Bottlenose dolphin has been noticed and recorded as they call out the specific names of others of their kind when separated. Apart from humans, dolphins are the only animals known to call other members of their species by name explicitly.
Dolphins have also been seen caring for injured members of their species and helping humans adrift at sea.
Because they are more gregarious, dolphins are now popular animals for training in captivity, which is a situation that porpoises do not adapt to effectively.
