Thursday, January 2, 2020

False Killer Whale Facts

False killer whales are part of class Mammalia and can be found in temperate and tropical waters. They spend most of their time in deeper waters but sometimes travel to coastal areas. Their genus name Pseudorca comes from the Greek word Pseudes, which means false. False killer whales are the third largest dolphin species. False killer whales are so named due to the similarity of their skull shape to killer whales. Fast Facts Scientific Name: Pseudorca crassidensCommon Names: False killer whalesOrder: CetaceaBasic Animal Group: MammalSize: 19 to 20 feet for males and 14 to 16 feet for femalesWeight: Around 5,000 pounds for males and 2,500 pounds for femalesLife Span: 55 years on averageDiet: Tuna, squid, and other fishHabitat: Warm temperate or tropical watersPopulation: Estimated 60,000Conservation Status: Near threatenedFun Fact: In rare cases, false killer whales have mated with bottlenose dolphins and created a hybrid known as a wolphin Description False killer whales have dark gray or black skin with a lighter gray throat. Their dorsal fin is tall and tapered to stabilize them as they swim, and their flukes propel them in the water. These dolphins have 8 to 11 teeth on either side of their jaw, and their upper jaw extends slightly beyond the lower jaw, which gives them a beaked look. They have bulbous foreheads, a long slim body, and long S-shaped flippers. Habitat and Distribution These dolphins are found across the world in temperate and tropical waters, preferring deeper waters at depths averaging 1,640 feet. Not much is known about any migration patterns because the populations are so spread out and they tend to stay in deeper water. The current knowledge of false killer whales comes from one population that lives off the shallower coasts of Hawaii. Diet and Behavior The diet of a false killer whale consists of fish like tuna and squid. They have attacked larger marine animals like smaller dolphins, but scientists are unsure if the purpose is to remove competition or for food. These dolphins can eat as much as 5% of their body weight every day. They hunt in dispersed subgroups during both day and night, swimming at depths of 980 to 1640 feet at high speeds for minutes at a time. They have been known to throw fish high into the air before eating them and to share prey. Pod of false killer whales, Revillagigedo Islands, Socorro, Baja California, Mexico. Romona Robbins Photography / Getty Images These dolphins are highly social creatures, swimming together in groups of 10 to 40 individuals. Some dolphins join superpods, which are congregations of up to 100 dolphins. Occasionally, they have been spotted swimming with bottlenose dolphins as well. During social events, they will leap out of the water and perform flips. They love to swim in the wake of ships and will even jump out of the water over the wake. They communicate via high pitched clicks and whistles, using echolocation to find other members of the group. Reproduction and Offspring While they breed year-round, false killer whales’ breeding tends to peak in late winter/early spring in December to January and again in March. Females reach sexual maturity between 8 and 11 years, while males reach sexual maturity between 8 and 10 years. Females’ gestation period is 15 to 16 months, and lactation lasts for up to two years. It is thought that females wait about seven years before having another calf. Between 44 and 55 years old, the females will enter menopause and become less successful reproductively. At birth, calves are just 6.5 feet in length and are capable of swimming alongside their mothers shortly after birth. Females typically only have one calf per breeding season. The mother nurses the baby for up to two years. Once the calf is weaned, it is likely to remain in the same pod it was born into. Threats There are four major threats that cause false killer whale populations to decline. The first is getting caught in fishing gear because they may get tangled as they take bait from fishing nets. A second is competition with fisheries, as their primary food—tuna—is also harvested by humans. The third is a risk of stranding due to environmental pollutants that disrupt their signals to each other. Finally, in Indonesia and Japan, they are hunted. Conservation Status False killer whales are designated as Near Threatened by the International Union for Conservation of Nature (IUCN). In Hawaii, they have issued changes in gear that allow animals to be released if accidentally caught. They have also removed seasonal contracts for fisheries to reduce overlap between fishing season and the false killer whale population. Sources Baird, R. W. False Killer Whale. IUCN Red List Of Threatened Species, 2018, https://www.iucnredlist.org/species/18596/145357488#conservation-actions.False Killer Whale. NOAA Fisheries, https://www.fisheries.noaa.gov/species/false-killer-whale.False Killer Whale. Whale Dolphin Conservation USA, https://us.whales.org/whales-dolphins/species-guide/false-killer-whale/.False Killer Whale. Whale Facts, https://www.whalefacts.org/false-killer-whale-facts/.Hatton, Kevin. Pseudorca Crassidens. Animal Diversity Web, 2008, https://animaldiversity.org/accounts/Pseudorca_crassidens/.

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