The cat is a very vocal animal. Known for its trademark purring, it also produces a wide variety of other sounds. The mechanism by which cats purr is elusive. The cat has no unique anatomical feature that is clearly responsible for the sound.[157][clarification needed] It was, until recent times, believed that only the cats of the Felis genus could purr. However, felids of the Panthera genus (tiger, lion, jaguar and leopard) also produce sounds similar to purring, but only when exhaling. A purr is a sound made by all species of felids and is a part of cat communication. It varies between cats (for example by loudness and tone), and from species to species, but can be characterized as a tonal buzzing. The term "purring" has been used liberally in literature, and it has been claimed that viverrids (civet, mongoose, genet), bears, badgers, hyaenas (et cetera) purr. Other animals that have been said to purr are rabbits, squirrels, guinea pigs, tapirs, ring-tailed lemurs, elephants,[1] raccoons and gorillas while eating. However, using a strict definition of purring that continuous sound production must alternate between pulmonic egressive and ingressive airstream (and usually go on for minutes), Peters (2002), in an exhaustive review of the scientific literature, reached the conclusion that until then only ‘purring cats’ (Felidae) and two species of genets, Genetta tigrina, and most likely also Genetta genetta, had been documented to purr. Cat communication is the range of methods by which cats communicate with other cats, humans, and other animals. Communication methods include postures, movement (including "quick, fi e" movements not generally perceived by human beings), noises and chemical signals.[1] The communication methods used by cats have been affected by the domestication process.[2]Cats vocalize with purrs, growls, hisses, and meows. Meows are one of the most widely known cat sounds. In nature, the meow is a sound used by a cat to signal a request to its mother. Adult cats do not meow to each other, and so the meowing to human beings that domesticated cats exhibit is likely partly an extension of the use by kittens of this plaintive meow signal.[3] The word "meow" is onomatopoeic. Different languages have correspondingly different words for the "meow" sound, including miau (Belarusian, Dutch, Finnish, Lithuanian, German, Polish, Russian, Portuguese, Romanian, Malay and Spanish), niau (Ukrainian), niaou (?,[4] Greek), miaou (French), nya (, Japanese), miao (?, Mandarin Chinese, Italian), miav/miao or mjav/mjau (Danish and Norwegian), mja (Icelandic), ya-ong (, Korean) and meo-meo (Vietnamese).[5] In a recent study, Dr Susanne Schotz of Lund University Sweden, provides an acoustic analysis of a number of felid vocalizations, including chatters, miaows, murmurs and combinations of these sounds.[6] Most cats growl or hiss when angered or feeling threatened, which serves as a warning to the offending party. If the warning is not heeded, a more serious attack may follow. Some may engage in behavior[clarification needed] or batting with their paws, with claws either extended or retracted. Cats sometimes make chirping or chattering noises when observing prey. A "caterwaul" is the cry of a cat in estrus (or "in heat").