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Tortoises () are a family, Testudinidae, of land-dwelling vertebrates in the order Testudines. Tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The carapace is fused to both the vertebrae and ribcage, and tortoises are unique among vertebrates in that the pectoral and pelvic girdles are inside, rather than outside, the ribcage. Tortoises can vary in size from a few centimeters to two meters. They are usually diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals. ==Use of the terms turtle, tortoise, and terrapin== Differences exist in usage of the common terms turtle, tortoise, and terrapin, depending on the variety of English being used; usage is inconsistent and contradictory.〔Simoons, Frederick J. (1991). ''Food in China: A Cultural and Historical Inquiry''. CRC Press. ISBN 084938804X. p. 358.〕 These terms are common names and do not reflect precise biological or taxonomic distinctions.〔Burton, Maurice and Burton, Robert (2002). ''International Wildlife Encyclopedia''. Marshall Cavendish. ISBN 0761472665. p. 2796 .〕 The American Society of Ichthyologists and Herpetologists uses "turtle" to describe all species of the order Testudines, regardless of whether they are land-dwelling or sea-dwelling, and uses "tortoise" as a more specific term for slow-moving terrestrial species.〔 General American usage agrees; turtle is often a general term (although some restrict it to aquatic turtles); tortoise is used only in reference to terrestrial turtles or, more narrowly, only those members of Testudinidae, the family of modern land tortoises; and terrapin may refer to turtles that are small and live in fresh and brackish water, in particular the diamondback terrapin (''Malaclemys terrapin'').〔Orenstein, Ronald Isaac (2001). ''Turtles, Tortoises and Terrapins: Survivors in Armor''. Firefly Books. ISBN 1770851194〕〔(【引用サイトリンク】title=Turtle )〕〔(What is the difference between turtles, terrapins, and tortoises? ), North Carolina Aquariums (July 1997).〕〔Dawkins, Richard (2009). ''The Greatest Show on Earth: The Evidence for Evolution''. Free Press. ISBN 1416594795. p. 174.〕 In America, for example, the members of the genus ''Terrapene'' dwell on land, yet are referred to as box turtles rather than tortoises.〔 British usage, by contrast, tends not to use "turtle" as a generic term for all members of the order, and also applies the term "tortoises" broadly to all land-dwelling members of the order Testudines, regardless of whether they are actually members of the family Testudinidae.〔 In Britain, terrapin is used to refer to a larger group of semiaquatic turtles than the restricted meaning in America.〔〔''Endangered Wildlife and Plants of the World'', Vol. 1. Marshall Cavenish. (2001). ISBN 0761471952. p. 1476.〕 Australian usage is different from both American and British usage.〔 Land tortoises are not native to Australia, yet traditionally freshwater turtles have been called "tortoises" in Australia.〔Romanowski, Nick (2010). ''Wetland Habitats: A Practical Guide to Restoration and Management''. CSIRO Publishing. ISBN 9780643096462. p. 134.〕 Some Australian experts disapprove of this usage—believing that the term tortoises is "better confined to purely terrestrial animals with very different habits and needs, none of which are found in this country"—and promote the use of the term "freshwater turtle" to describe Australia's primarily aquatic members of the order Testudines because it avoids misleading use of the word "tortoise" and also is a useful distinction from marine turtles.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「tortoise」の詳細全文を読む スポンサード リンク
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