False killer whale

The false killer whale (Pseudorca crassidens) is a large species of oceanic dolphin. It is the only living member of the genus Pseudorca. These animals are found in oceans across the globe, though they mostly live in tropical and subtropical regions. They prefer the open ocean and deep-water areas. They generally do not swim further north or south than 50 degrees latitude.

These dolphins are highly social animals that live in complex groups called pods. Most pods consist of 10 to 20 members. However, they can also form much larger groups containing more than 500 whales. They are believed to have a matrifocal structure. This means that mothers lead the pods instead of fathers. Members often stay with their pods for a long time, sometimes for 15 years. This strong social bond can lead to mass strandings. In 1946, over 800 whales stranded at Mar del Plata, Argentina.

False killer whales are powerful predators that use echolocation to navigate. They use a specialized organ in their forehead called a melon to create sound. This sound helps them find prey in the dark. They typically hunt during the daylight hours. Their diet mainly consists of squid and various fish. They target large species like tuna, wahoo, and mahi-mahi. Sometimes, they also prey on other marine mammals, including smaller dolphins and even whales.

They are known for their unique ability to interact with other dolphin species. They often form mixed-species pods with common bottlenose dolphins. These interactions are non-aggressive and may happen because the groups share feeding grounds. They have even been known to assist other species during childbirth. In some cases, false killer whales can hybridize with bottlenose dolphins. This produces fertile offspring known as "wholphins."

The history of this species involves several scientific revisions. In 1846, the British biologist Richard Owen first described the species. He based his description on a fossil skull found in England. He originally placed them in the genus Phocaena, which includes porpoises. In 1861, the species was thought to be extinct until carcasses were found in Denmark. In 1862, zoologist Johannes Theodor Reinhardt moved them to the genus Pseudorca. The name "false killer whale" was chosen because their skulls look similar to the orca.

Physically, the false killer whale is the fourth-largest oceanic dolphin. Only the orca and two species of pilot whales are larger. Females can reach a maximum length of 6 meters. Males are generally 10 to 15 percent larger than females. They have dark gray or black skin that is lighter on the underside. They reach sexual maturity between 8 and 11 years of age. In captivity, females have lived up to 62 years.

Human activities can impact these populations significantly. They are threatened by fishing operations where they can become entangled in gear. In Hawaii, these issues helped reduce the local population by 75 percent between 1989 and 2009. They may also swallow fishing hooks, which can cause internal damage. Because they are high up in the food chain, they are also susceptible to the buildup of organochlorides. Scientists continue to learn about them by studying individuals that strand on beaches.