Organohalogen compounds in blubber of Indo-Pacific bottlenose dolphin (Tursiops aduncus) and spinner dolphin (Stenella longirostris) from Zanzibar, Tanzania

Several methods have been used to compare the whistles produced by dolphins. The two methods used in this study are: (1) a classification of whistle contours in six categories (i.e. constant frequency, upsweep, downsweep, concave, convex, and sine) and (2) the extraction of frequency and time parameters from each whistle contour. Bottlenose Dolphin Tursiops truncatus whistles are described in the same way when comparing whistle contour distributions in each of the six categories and whistle frequency and time parameters using Discriminant Function Analysis. For Spinner Dolphin Stenella longirostris whistles, each method describes whistles differently. Several facts may explain these differences in describing dolphin whistles, such as a greater fluidity of Spinner Dolphin groups when compared to Bottlenose Dolphin groups, greater geographic variation in the whistles of Bottlenose Dolphins than in those of Spinner Dolphins, an average beginning frequency 16% lower than the average ending frequency in Spinner Dolphin whistles compared to a varied relationship for Bottlenose Dolphins, and stricter criteria used to define whistle contour categories in the study of Spinner Dolphin whistles than in the Bottlenose Dolphin whistle study.

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First record of the Spinner Dolphin Stenella longirostris longirostris (Cetacea: Delphinidae) for Kosrae, Micronesia

Check List ◽

10.15560/13.4.31 ◽

2017 ◽

Vol 13 (4) ◽

pp. 31-34

Author(s):

Floyd E Hayes ◽

Brandon J Painter

Keyword(s):

First Record ◽

Stenella Longirostris ◽

Spinner Dolphin

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Taxonomy and distribution of bottlenose dolphins (genus Tursiops) in Australian waters: an osteological clarification

Canadian Journal of Zoology ◽

10.1139/cjz-2018-0270 ◽

2020 ◽

Vol 98 (7) ◽

pp. 461-479 ◽

Cited By ~ 1

Author(s):

M. Jedensjö ◽

C.M. Kemper ◽

M. Milella ◽

E.P. Willems ◽

M. Krützen

Keyword(s):

Bottlenose Dolphin ◽

Bottlenose Dolphins ◽

Three Dimensional ◽

Large Sample Size ◽

Type Specimens ◽

Tursiops Aduncus ◽

Common Bottlenose Dolphin ◽

Intermediate Size ◽

The Common ◽

Taxonomic Studies

Species relationships in the bottlenose dolphin (genus Tursiops Gervais, 1855) are controversial. We carried out a comprehensive osteological study of 264 skulls, including type specimens, and 90 postcranial skeletons of Tursiops spp. to address taxonomic uncertainties in Australia using two-dimensional (2D) measurements, and three-dimensional geometric morphometrics (3DGM), tooth and vertebral counts, and categorical data. Analyses provided support for the presence of two forms, aligned to the Indo-Pacific bottlenose dolphin (Tursiops aduncus (Ehrenberg, 1832)) and the common bottlenose dolphin (Tursiops truncatus (Montagu, 1821)), including type specimens. The Burrunan dolphin (Tursiops australis Charlton-Robb, Gershwin, Thompson, Austin, Owen and McKechnie, 2011) fell well within T. truncatus for both 2D and 3DGM methods. Thirteen Tursiops spp. specimens, no T. australis specimens, were of intermediate size (2D) and could not be assigned to either species. For 3DGM data, there was a strong allometric influence and few non-allometric differences between species. Length and width of the cranium and rostrum were important discriminating variables. Tursiops aduncus was smaller, had more teeth, fewer vertebrae, and more erosion on the pterygoids and frontals than T. truncatus. Overall cranium shape was round in T. aduncus and angular in T. truncatus. Skull length of T. aduncus was smaller in low than in high latitudes. This study highlights the importance of large sample size, multiple analytical methods, and extensive geographical coverage when undertaking taxonomic studies.

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