False killer whale
|False killer whale|
|Size compared to an average human|
|False killer whale range|
The false killer whale (Pseudorca crassidens) is a cetacean, and the third-largest member of the oceanic dolphin family (Delphinidae). It lives in temperate and tropical waters throughout the world. As its name implies, the false killer whale shares characteristics, such as appearance, with the more widely known killer whale (orca). Like the orca, the false killer whale attacks and kills other cetaceans, but the two species do not belong to the same genus.
The false killer whale has not been extensively studied in the wild; much of the data about it has been derived by examining stranded animals. The species is the only living member of the Pseudorca genus.
The false killer whale was first described by the British paleontologist and biologist Richard Owen in his 1846 book A history of British fossil mammals and birds. He based this work on a fossil discovered in 1843 in the great fen at the neighourhood of Stamford, Lincolnshire. Owen proposed to name the cetacean Phocaena crassidens and, by comparing its characteristics and dimensions, noted a general resemblance to those of the grampus (Phocaena orca) and the round-headed porpoise (Phocaena melas).
The species was thought extinct until Reinhardt confirmed it was alive when he described a large pod at the Kiel Bay in 1861. One of these was captured, and others were found the following year, beached on the coast of Denmark.
Population and distribution
The false killer whale appears to have a widespread, if small, presence in tropical and semitropical oceanic waters. A few of these whales have been found in temperate water, but these are probably stray individuals. Their most common habitat is the open ocean, though they also frequent other areas. They have been sighted in fairly shallow waters such as the Mediterranean Sea and Red Sea, as well as the Atlantic Ocean (from Scotland to Argentina), the Indian Ocean (in coastal regions and around the Lakshwadweep Islands), the Pacific Ocean (from the Sea of Japan to New Zealand and the tropical area of the eastern side), and in Hawaii.
The Hawaii populations are the most studied groups of false killer whales. The three distinct groups in the islands are an offshore population, a northwestern Hawaiian Island group, and a small group around the main Hawaiian Islands. This last group, a unique, small, insular population, is genetically distinct from the other populations.
The false killer whale is black with a grey throat and neck. It has a slender body with an elongated, tapered head and 44 teeth. The dorsal fin is sickle-shaped and its flippers are narrow, short and pointed. The average size is around 4.9 m (16 ft). Females can reach a maximum known size of 5.1 m (17 ft) in length and 1,200 kg (2,600 lb) in weight, while the largest males can reach 6.1 m (20 ft) and as much as 2,200 kg (4,900 lb).
False killer whales are kept in captivity and studied in the wild by scientists. Several public aquaria display false killer whales. For example, Okinawa Churaumi Aquarium in Japan displays false killer whales in the Okichan Theater. A false killer whale and a bottlenose dolphin mated in captivity and produced a fertile calf.
Scientist have undertaken research to understand more about the species—including population surveys, satellite tagged individual whales, and carcasses studies. From these studies, they determined information about habitat, range, and distinct populations. Recent study of the local population of false killer whales in Hawaii shows evidence of a dramatic decline over the last 20 years. Five years of aerial surveys from 1993 through 2003 show a steep decline in sighting rates. Group sizes of the largest groups documented prior to 1989 surveys were almost four times larger than the entire 2009 population estimate.
On 30 July 1986, a pod of 114 false killer whales became stranded at Town Beach, Augusta, in Flinders Bay, Western Australia. In a three-day operation, coordinated by the Department of Conservation and Land Management, volunteers carried 96 of the whales on trucks to more sheltered waters, and then successfully guided them out into the bay.
On 2 June 2005, up to 140 (estimates vary) false killer whales were beached at Geographe Bay, Western Australia. The main pod, which had split into four separate strandings along the length of the coast, was successfully moved back to sea, with only one death after the intervention of 1,500 volunteers, coordinated once again by the Department of Conservation and Land Management.
Just prior to sunrise on 30 May 2009, a pod of 55 false killer whales was discovered beached on a sandy beach at Kommetjie in South Africa (latitude 34° 8′ 3.98″ S, longitude 18° 19′ 58.22″ E). By 9 am, 50 or more volunteers had already arrived to help move the whales into the ocean. Many more volunteers came throughout the day to offer their services. However, their efforts were futile with most animals re-beaching themselves and the weather complicating further attempts. By late morning, the authorities decided to ask volunteers to stabilize the false killers whales on the beach. No further attempt was made to take the whales into the open sea. At about 4 pm after considerable debate by all the authorities present, the decision was made to initiate euthanasia by shooting the whales; around 44 whales were killed.
The false killer whale is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS), and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)
In November 2012, the United States' National Oceanic and Atmospheric Administration recognized the Hawaiian population of false killer whales, which numbers around 150 individuals, as endangered.
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- Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
- Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
- Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region