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creek whaler
The creek whaler (''Carcharhinus fitzroyensis'') is a common species of requiem shark, and part of the family Carcharhinidae, endemic to northern Australia. It frequents shallow waters close to shore, including estuaries. This small, stocky shark usually grows to long and is brownish in color without conspicuous fin markings. It can be identified by its long snout, large, triangular pectoral fins, and large, anteriorly positioned first dorsal fin.
The diet of the creek whaler consists mainly of small teleost fishes and crustaceans. It is viviparous, with the unborn young being sustained through a placental connection. The defined mating season lasts from May to July. Females give birth to one to seven pups annually, following a gestation period of seven to 9 months. A small number of creek whalers are caught incidentally in inshore gillnets and used for food, but the effect of fishing on its population seems to be inconsequential. As a result, the IUCN has listed this species under Least Concern.
==Taxonomy and phylogeny==
The creek whaler was described by Australian ichthyologist Gilbert Percy Whitley in a 1943 volume of ''Proceedings of the Linnean Society of New South Wales''. He assigned the new species to the subgenus ''Uranganops'' of the genus ''Galeolamna'', and gave it the specific epithet ''fitzroyensis'' because the type specimen, a 1.2-m-long female, was collected from Connor's Creek in the Fitzroy River estuary.〔 Subsequent authors have synonymized ''Galeolamna'' with ''Carcharhinus''.〔
The evolutionary relationships of the creek whaler have yet to be fully resolved. In comparative morphological studies published by Jack Garrick in 1982 and Leonard Compagno in 1988, it was tentatively placed in a grouping defined by the whitecheek shark (''C. dussumieri'') and the blackspot shark (''C. sealei'').〔〔 Shane Lavery, in a 1992 study based on allozymes, reported that this species was close to the nervous shark (''C. cautus'') and the blacktip reef shark (''C. melanopterus'').〔 Ximena Vélez-Zuazoa and Ingi Agnarsson, in a 2011 study based on nuclear and mitochondrial genes, found it to be the basal member of a clade also containing the graceful shark (''C. amblyrhynchoides''), the blacktip shark (''C. limbatus''), and the Australian blacktip shark (''C. tilstoni'').〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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