False Killer Whale

The False Killer Whale (Pseudorca crassidens) is a dolphin found in temperate and tropical waters throughout the world. As its name implies, the False Killer Whaleshares characteristics with the more widely known Killer Whale . The twospecies look somewhat similar and, like the Killer Whale, the False Killer Whale attacks and kills other cetacea .

The False Killer Whale has not been extensively studied in the wild by scientists - much of the data about the whale has beenderived by examining stranded animals.

The species is the only member of the Pseudorca genus.

Physical description

This dolphin has a slender body with a falcate dorsal fin that may be morethan a foot high. One of the species distinguishing characteristics is a bend and bulge (usually called the "elbow") half-wayalong each of the flippers. The tips of the tail fin are pointed and the middle of the tail has a distinct notch. The head isslender with a rounded beak. The False Killer is uniformly coloured a dark grey to black. The scientific specific namecrassidens comes from the Latin for 'dense-toothed'.

The False Killer Whale is a social animal - it lives in groups of 10-50 and exceptionally in groups as large as 300. It is afast and very active swimmer. It may breach or jump clear of the water and will often land on its side with a big splash. Onother occasions the dive may be very graceful - living very little wake at all. It will readily approach boats and bow- and wake-ride. It may also emerge from the water head held high upwards and with the mouth open - revealing some of its 48 teeth.

False Killer Whales have been observed attacking smaller dolphins and whales in the tuna feeding grounds of the tropicaleastern Pacific. It is not known whether this is typical behaviour. Researchers have also observed the False Killer attacking andbiting larger whales, such as the Sperm Whale. The food that the species consumes varies from region to region like the KillerWhale - different populations specialise on various fish and cephalopods .Co-operation between individuals has been observed when feeding - a pod will form a straight line and comb a particular area ofsea, presumably seeking food.

The dolphin grows to about 6m long, may weigh 1,500kg and lives for about 60 years.

Population and distribution

Although not often seen at sea, the False Killer Whale appears to have a widespread, if rare, distribution in temperate andtropical oceanic waters. They have been sighted in fairly shallow waters such as the Mediterranean and Red Seas as well as the Atlantic (from Scotland to Argentina ), Indian (incoastal regions) and Pacific (from the Sea of Japan to New Zealand and the tropical area of the eastern side) Oceans.

The total population is unknown. The eastern Pacific was estimated to have in excess of 40,000 individuals and is probably thehome of the largest grouping.

Human interaction

The False Killer Whale has been hunted, but not extensively in the WestIndies and Indonesia . Japan usuallykills a small number of individuals each year.

False Killers have long caused anger amongst fishermen fishing for tuna and yellowtail . The dolphins take the fish from the longlines used by the fishermen. Thisled to a concerted effort from Japanese fisherman working from Iki Island to deplete the species in the area - 900 inidividuals were killed for this purposebetween 1965 and 1990.

References

• National Audubon Society: Guide to Marine Mammals of the World ISBN 0375411410
• Encyclopedia of Marine Mammals ISBN 0125513402