porpoise
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What is a porpoise?
A porpoise is any of the seven species of toothed whales in the family Phocoenidae. They are related to dolphins and other toothed whales. Porpoises are smaller than dolphins, reaching a maximum length of about 2 meters (6.6 feet), and are more compact. They have curved, blunt snouts and spade-shaped teeth, whereas dolphins have conical teeth and pronounced beaks. Porpoises generally have triangle-shaped dorsal fins, while those of dolphins are usually hooked or curved.
The porpoise family consists of the genera Phocoena, Phocoenoides, and Neophocaena. They eat fish and swim in pairs or small groups along coastlines and occasionally in rivers.
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How is a porpoise different from a dolphin?
Porpoises and dolphins, both members of the Cetacea group, share a common classification as marine mammals and carnivores, yet they exhibit distinct physical differences. Porpoises are generally smaller with a compact build, reaching a maximum length of about 6.6 feet (2 meters). Unlike dolphins, they feature curved, blunt snouts and spade-shaped teeth, as opposed to the cone-shaped teeth of dolphins. Also, porpoises possess triangle-shaped dorsal fins, while dolphins usually have hooked or curved ones. There are over 30 species of dolphins.
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Where do porpoises live?
Porpoises are found in various regions around the world. The harbour porpoise, Phocoena phocoena, inhabits much of the Northern Hemisphere, while Dall porpoises, Phocoenoides dalli, live along the northern rim of the Pacific Ocean. Finless porpoises (Neophocaena phocaenoides and N. asiaeorientalis) occupy coastal waters and rivers along the Indian and western Pacific Oceans. Burmeister’s porpoise (P. spinipinnis) lives off the coasts of eastern and western South America, and the spectacled porpoise (P. dioptrica) is distributed throughout the southern Indian, Atlantic, and Pacific oceans. The vaquita (P. sinus) is localized to the northern end of the Gulf of California.
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What do porpoises eat?
Porpoises are marine mammals closely related to dolphins. There are seven species of porpoises, and their diets vary depending on the species and their habitat.
The Phocoena species, including the harbor porpoise, primarily eat fish. Dall porpoises consume squid and fish and are usually seen in groups of 2 to 20 along the northern rim of the Pacific Ocean. Finless porpoises, found in coastal waters and rivers along the Indian and western Pacific Oceans, eat crustaceans, fish, and squid.
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How do porpoises communicate with each other?
Porpoises, like other toothed whales, communicate using high-pitched clicking sounds ranging from 5 to 150 kHz. They produce these sounds by blowing air through vibrating tissues in their nasal passages. The clicking sounds travel through a fatty organ called the melon, located on their forehead, and then project into the water.
When these sound waves strike an object, they bounce back to the porpoise, and the vibrations are conveyed to the inner ear via a structure in the lower jaw. This process, known as echolocation, allows porpoises to navigate, find food, avoid obstacles, and engage in social interactions.
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Why are porpoises sometimes threatened or endangered?
Porpoises, belonging to the family Phocoenidae, face threats that lead to some species being classified as threatened or endangered. The vaquita, for example, is critically endangered due to becoming trapped as bycatch in illegal gill nets, which prevents them from reaching the surface to breathe. This is made worse by lax enforcement of laws. Similarly, the Yangtze finless porpoise is also critically endangered, with its population having declined significantly since 1984.
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porpoise, (family Phocoenidae), specifically, any of seven species of toothed whales distinguishable from dolphins by their more compact build, generally smaller size (maximum length about 2 metres, or 6.6 feet), and curved blunt snout with spatulate rather than conical teeth. In North America the name is sometimes applied to dolphins. The porpoise family consists of three genera: Phocoena, Phocoenoides, and Neophocaena.
The four Phocoena species are primarily fish eaters that usually swim in pairs or small groups along coastlines and occasionally in rivers. They are gray or black above and white below. Best known of these is the harbour porpoise, Phocoena phocoena, a shy cetacean that generally avoids boats and rarely leaps above the water. It is found throughout much of the Northern Hemisphere and is hunted in some regions. During the Middle Ages this animal was considered a royal delicacy. The other members of the genus are more restricted in distribution. The vaquita, or cochito (P. sinus), is listed as a critically endangered species by the International Union for Conservation of Nature (IUCN). Vaquitas are found only near the northern end of the Gulf of California. By 2020, ecologists had estimated that no more than 18 adults remained. Burmeister’s porpoise (P. spinipinnis) has blunt tubercles on its dorsal fin and lives off the coasts of eastern and western South America. The spectacled porpoise (P. dioptrica) is named for the patchlike pigmentation pattern around its eyes and is distributed throughout the southern Indian, Atlantic, and Pacific oceans.
The Dall porpoise (Phocoenoides dalli) is the largest porpoise and the only member of its genus. Active and gregarious, it often rides the bow waves of ships. The Dall porpoise is black with a large white patch on each side of the body. It is usually seen in groups of 2 to 20 along the northern rim of the Pacific Ocean, where it eats squid and fish. True’s porpoise (P. dalli truei) is considered by some authorities to be a separate subspecies and is distinguished from the Dall porpoise by its absence of the striking white body patches. It is found only near Japan.
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The finless porpoises (Neophocaena phocaenoides and N. asiaeorientalis) are small slow-moving inhabitants of coastal waters and rivers along the Indian Ocean and western Pacific Ocean. Black above and white below, finless porpoises have a rounded head. Unlike other porpoises, they lack a dorsal fin entirely. Finless porpoises live alone or in small groups and eat crustaceans, fish, and squid. Both species are considered vulnerable; however, the population of the Yangtze finless porpoise (N. asiaeorientalis asiaeorientalis), a subspecies of narrow-ridged finless porpoise found only in the Yangtze River, has declined significantly since 1984. It was classified as a critically endangered species by the IUCN in 2013.
Members of the family Phocoenidae are related to the oceanic dolphins (family Delphinidae), river dolphins, and other toothed whales of the suborder Odontoceti. The common name is derived from the Latin porcus (“hog” or “pig”) and piscinus (“fish”), as their flesh was said to taste somewhat like pork.