Phocoenidae Family of True Porpoises
One True Porpise of the Phocoenidae Family can be found in this website:
Dall’s Porpoise, Phocoenoides dalli. A representative of the Phocoenidae Family of True Porpoises.
Phylogeny: True Porpoises of the Phocoenidae Family are marine mammals. Like all mammals, they are in the phylum Chordata, the subphylum Vertebrata, the infraphylum Gnathostomata, the megaclass Tetrapoda, and the class Mammalia. They are in the subclass Theria of viviparous (live-bearing) mammals. They are in the order Cetartiodactyla and the suborder Cetancodonta. True Porpoises are in the infraorder Cetacea, which contains two superfamilies- Mysticeti (baleen whales), and Odontoceti (dolphins and toothed whales). The Phocoenidae Family is one of seven families in the Odontoceti superfamily. The Phocoenidae Family contains three genera and seven species. The name Phocoenidae comes from the Greek word meaning “porpoise”. This name was Latinized to literally mean “pig fish”, referring to the animal’s snout. The common name True Porpoises is used to distinguish them from dolphins and whales, with which they are colloquially intermixed.
Morphology: Unlike Oceanic Dolphins of the Delphinidae Family, True Porpoises have spade shaped teeth for cutting, rather than cone shaped teeth. They are stockier than Oceanic Dolphins, and generally have a shorter, or nonexistent, beak. Their dorsal fins are smaller and triangular, instead of falcate. True Porpoise flippers are narrower than those of Oceanic Dolphins. They are generally smaller than Dolphins, with none longer than 2.4 m (7 feet 10 inches). The smallest of the True Porpoises is the Vaquita Dolphin. The Vaquita reach a maximum length of 1.45 m (4 feet 9 inches).
Habitat and Distribution: True Porpoises are found in open oceanwaters, bays, harbors, and coastal waters. Dall’s Porpoise is the only real offshore species. As air breathing mammals they need to come to the surface to breath and will often rest at the surface, but all species need to dive to hunt. True Porpoises are not known for being deep divers, but the Harbor Porpoise has been documented to exceed 200 m (650 feet). True Porpoises tend to be found more inshore than Dolphins, reside in smaller groups, and have simpler social interactions. They are found worldwide in temperate to tropical oceans. Two species from this family are found in Mexican waters. This includes the Vaquita, which has the smallest range of any marine cetacean. They are found only in the extreme northern portion of the Gulf of California. Because of this limited range, loss of breeding habitat, a propensity to become entangled in fishing gear, the Vaquita currently has minimal populations (as in a handful but they are difficult to count accurately) and is considered to be ENDANGERED. They are on the brink of extinction. Mexico has responded by making the upper northern portions of the Sea of Cortez a biosphere reserve, but illegal fisheries continue to threaten the remaining individuals.
Reproduction: As mammals, True Porpoises are gonochoric (male or female for life) and reproduce sexually with internal fertilization. Females give birth to a single calf, generally after a ten to eleven month gestation period. The calves will nurse for eight to twelve months. Most species give birth annually, with the Vaquita being a notable exception.
Ecosystem Roles: True Porpoises are predatory carnivores that primarily eat fish and squid. In turn they are preyed upon by large sharks and Killer Whales.