Hookfin porpoise
The Pacific white-sided dolphin (Lagenorhynchus obliquidens ), also known as the hookfin porpoise, is a very active dolphin found in the cool or temperate waters of the North Pacific Ocean.
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NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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MolluscivoreA molluscivore is a carnivorous animal that specializes in feeding on molluscs such as gastropods, bivalves, brachiopods, and cephalopods. Known mo...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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AquaticAn aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract ...
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PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
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NomadicNomadic animals regularly move to and from the same areas within a well-defined range. Most animals travel in groups in search of better territorie...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
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PolygynyPolygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
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ColonialColonial animals live in large aggregations composed of two or more conspecific individuals in close association with or connected to, one another....
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withPacific white-sided dolphin is identified by the unusually large, curved dorsal fin, due to which the animal is sometimes called "hookfin porpoise", although it's not a porpoise. The sides and underneath of the dolphin are white. The animal is dark grey on top with a faint gray band, running along either side, starting above each eye and widening towards the tail. The small beak is dark, and the dolphin exhibits dark rings around the eyes. Pacific white-sided dolphins are also strong and fast swimmers. These playful animals are known to bow-ride, remaining around moving vessels for long periods of time.
This species is endemic to North Pacific, where the animal is typically found in deep, cool to temperate waters. The area of Pacific white-sided dolphin's population extends to the South China Sea in the south and the Baja California Peninsula in the east. These dolphins are also known to occur in the Sea of Japan and the Sea of Okhotsk. In the north, the animals can be found in the Bering Sea. On the eastern side of their range, Pacific white-sided dolphins display somewhat migratory behavior, living in the Southern California Bight in winter and moving to Oregon (Washington) in summer.
These highly social animals are occasionally observed in large schools of more than 1000 individuals. However, schools of 50 individuals are most common. Groups of Pacific white-sided dolphins typically include individuals of both sexes and different ages, generally getting along well with each other. Moreover, these dolphins are known to associate with other dolphin species, often feeding in the same areas without any conflicts. Within a group, it is common to help ill or hurt individuals. These animals prefer feeding by night, when fish shcools come closer to the water surface.
These dolphins are carnivores (piscivores), they usually prey on large schools of fish, preferring anchovies, herring, smelt, capelin, and mackerel.
Pacific white-sided dolphins have polygynous mating system. Groups of this species contain individuals of both sexes, but only the dominant male mates with females of the pod. They typically breed in summer-autumn. Females give birth with intervals of 4.5 - 5 years. The gestation period lasts for 11 - 12 months, yielding a single baby, which is nursed by its mother for 8 - 10 months. Even after weaning, the female continues caring for her offspring for 2 - 3 years. Sexual maturity is reached within 5 - 6 years in females and by 8 - 10 years old - in males.
Presently, Pacific white-sided dolphins are often incidentally caught in fisheries like gillnets or trawls. In the North Pacific part of their range, the animals are occasionally captured in purse-seine fisheries. The species is also hunted by Japanese coastal fishermen in the East China and Japan seas.
According to IUCN, the Pacific white-sided dolphin is abundant and widespread throughout its range but no overall population estimate is available. However, there are estimates of its population in following areas: the central North Pacific, which is likely to hold 900,000-1,000,000 individuals; and the U.S. West Coast - about 24,000 dolphins. Currently, Pacific white-sided dolphins are classified as Least Concern (LC) on the IUCN Red List.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...