Different Types of Porpoises

The term porpoise is used to refer to the smallest types of cetaceans, a group which belong to the family Phocoenidae, scinetically known as phoecoenids. They are classified within the clade Odontoceti which also contains cetaceans with teeth. Although known as toothed whales, porpoises are not types of whale and dolphins are also included in this clade.

Most porpoise types of porpoise species are marine mammals, meaning they live in ocean waters. However, there is one kind of porpoise which has adapted to living exclusively in fresh waters. While the habitats of porpoises are aquatic, they can differ greatly between species. For example, some are known to inhabit warm tropical waters, while others live in freezing polar regions. Each species is known to live in its own particular geographic area.

To learn more about the classification of cetaceans, take a look at our related article asking do all whales have teeth?

While different porpoise species will have individual characteristics, they all share certain traits and behaviors. These characteristics of porpoises include the following:

• Teeth: being odontocetes, porpoises have teeth with which they use to prey on different animals for food. Porpoise teeth are flattened in shape, giving them distinct characteristics.
• Diet: the porpoise diet is based mainly on cephalopods such as squid, as well as small fish and benthic marine life that live on the bottom of a body of water. They also catch the occasional benthic invertebrate when foraging there. Among the fish they catch are sardines and capelins. They are capable of hunting fish in the water column.
• Hunting: to find their prey, porpoises use echolocation. This is an ability whereby they emit infrasonic sounds that are interpreted by an organ called a melon, mapping a certain area around the porpoise. Learn more about what is echolocation and what animals have it in our related guide.
• Respiration: they are mammals that breathe through lungs, so they have to come to the surface to inhale air. For this, they have their nostrils far back and are called spiracles .
• Swimming: porpoise limbs are modified into fins for agile swimming. They also have a hydrodynamic body shape to move skillfully in the aquatic environment.
• Mouth: finally, one of the diagnostic characteristics to know if a marine mammal is a porpoise is its short snout.

There are 8 different types of porpoise known to science, although there are also many more extinct species. Unfortunately, some of the current porpoise species are also in threat of extinction. We look at these types of porpoise species in detail below:

• Vaquita (Phocoena sinus): endemic to Baja California in Mexico, the vaquita measures 4.6 to 4.9 ft (1.4 to 1.5 m) in length, making it the smallest cetacean in the world. It is critically endangered due to incidental hunting and the restricted nature of its habitat. There are currently fewer than 10 living specimens left. They are known for their prominent lips and are shy in nature.
• Harbour porpoise (Phocoena phocoena): lives in the northernmost part of the planet, near the coasts or in estuaries. It is the most common type of porpoise and measures 4.6 to 6.6 ft (1.4 to 2 m) in length.
• Burmeister's porpoise (Phocoena spinipinnis): is native to the Southern Cone of South America, both on the Atlantic and Pacific sides of the ocean. They live near the coasts, but sometimes venture out to the open sea. On average, they measure 4.9 ft (1.5 m) in length. They are sometimes known as a black porpoise. Although their skin is grey like other different porpoises, it turns black once they die.
• Spectacled porpoise (Phocoena dioptrica): has a white underside and a dark grey upper side. It is also unusual because of markings around the eye which makes it appear as if it is wearing glasses. It measures 6.6 to 7.9 ft (2 to 2.4 m) in length. It is native to the southernmost tip of the planet.
• Dall's porpoise (Phocoenoides dalli): lives in the northernmost part of the Pacific Ocean. It is around 7.5 ft (2.3 m) long, making it one of the largest types of porpoise. It is characterized by being very dark in color, except for a large white spot on its underbelly. Due to these markings, it looks like a miniature orca. Learn about another cetecean that resembles this dolphin with our article on the difference between the orca and false killer whale.
• Finless porpoise (Neophocaena phocaenoides): the most peculiar trait about this type of porpoise is the fact it has no dorsal fin. It measures 3.3 to 4.9 ft (1 to 1.5 m) in length. It lives on the coasts of Asia, but reaches the Yangtze River.
• Australian porpoise (Phocoena australis): this species is found along the southern coasts of Australia. They typically measure about 3.9 to 4.9 ft (1.2 to 1.5 m) in length and are not as well-studied as other porpoise species.
• Yangtze finless porpoise (Neophocaena asiaeorientalis): another porpoise species known for a lack of dorsal fin, this is the only type of porpoise which has adapted to living in freshwater environments. Specifically, it only lives in the Yangtze River in China. It typically measures between 4.6 to 7.9 ft (1.4 to 2.4 m) in length and is critically endangered due to factors such as habitat loss and pollution.

Although it is not common, porpoises are known to beach themselves in certain circumstances. Learn more about cetacean stranding with our article on why dolphins and whales beach themselves.

As we have already stated, porpoises are often confused with dolphins. This is understandable due to their similar appearance. In fact, they were once classified as being in the same order, but phylogenetic studies have revealed that they are two separate groups. In addition to classification, they are considered different animals for a reason. This is due to several morphological differences between porpoises and dolphins:

• Porpoises are smaller than dolphins
• Porpoise spines are arched slightly downwards in a concave shape
• Dolphin spines are curved upwards in a convex shape
• Porpoises have flattened teeth and dolphins have conical teeth
• Dolphins have a characteristic elongated snout
• Porpoises have a less prominent and shortened short
• Dolphins are more social than porpoises and form complex groups of several individuals
• Dolphins have a more streamlined body than porpoises
• Dolphins have a crescent-shaped dorsal fin
• Porpoises have a triangular dorsal fin (if at all)

Learn more about one of these marine mammals with our article asking are dolphins dangerous to humans?

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