Biological data on two Hector's beaked whales, <i>Mesoplodon hectori</i>, stranded in Buenos Aires province, Argentina

Abstract

Abstract:Beaked whales or ziphiids are the least known cetaceans, and are among the least studied of all mammalian groups. In August and September of 2002, a male and a female beaked whale stranded alive on the Argentine coast, 110 km away from each other. The specimens died shortly after the stranding and their bodies were collected for dissection and analysis. The specimens were identified as belonging to the genus Mesoplodon. Further measurements of the skulls, shape and location of teeth as well as molecular analyses of the mtDNA control region and cytochrome b, allowed unambiguous identification of both specimens as Hector's beaked whale, Mesoplodon hectori. The color pattern was different between male and female. Standard length was 3.94 meters for the male and 3.84 meters for the female. The female's vertebral formula was C7 + T10 + L11 + Ca21 = 49. Histo-pathological analysis of the female revealed the presence of Sarcocystis sp. in the skeletal muscle, and lung lesions related to parasitic damage and pneumonia or chronic infection. The stomach of both individuals was empty. The digestive tract of both specimens was infected by larval stages L4 of Anisakis sp. The female was also infected by Tetrabothrius sp. and Bolbosoma sp. while Braunina cordiformis was only found in the male. Different composition of parasitic fauna suggests possible sex-related differences in the diet or individual variability. Total length, teeth eruption (in the male) and the degree of vertebral epiphyses fusion suggest that both individuals were mature.Resumen: Las ballenas picudas o zífidos son los cetáceos menos conocidos y además están entre los mamíferos existentes que menos se conocen. En agosto y septiembre de 2002 un macho y una hembra de ballenas picudas vararon vivas en la costa de Argentina, a 110 kilómetros una de otra. Los especimenes murieron poco después del varamiento y sus cuerpos fueron colectados para su disección y análisis. Los especimenes fueron identificados como pertenecientes al género Mesoplodon, a partir de medidas del cráneo, la forma y posición de los dientes y el análisis del ADNmt, región control y citocromo b, permitiendo identificar sin ambigüedad ambos especimenes como ballenas picudas de Héctor, Mesoplodon hectori. El macho y la hembra presentaron diferente patrón de coloración. La longitud estándar fue de 3,94 metros para el macho y de 3,84 metros para la hembra. La fórmula vertebral de la hembra fue C7 + T10 + L11 + Ca21 = 49. Análisis histopatológicos de la hembra revelaron la presencia de Sarcocystis sp. en el músculo esquelético, y lesiones pulmonares relacionadas con daño producido por parásitos y pneumonía o infección crónica. El estómago de ambos ejemplares se encontró vacío. El tracto digestivo de ambos especimenes se encontraba infectado por el estadio larval L4 de Anisakis sp. La hembra tenía Tetrabothrius sp. y Bolbosoma sp. Mientras que el macho tenía Braunina cordiformis en su estómago. La diferente composición de la fauna parasitaria de ambos individuos sugiere la existencia de po...

Description of a new long-snouted beaked whale from the Late Miocene of Denmark: evolution of suction feeding and sexual dimorphism in the Ziphiidae (Cetacea: Odontoceti)

“…The degree of fusion of the cervical vertebrae is variable in ziphiids and depends on age and species. Generally, in extant species, at least the three‐first centra are fused, except in the three following species: M. grayi , M. perrini and M. hectori (Flower, ; Oliver, ; Dalebout et al ., ; Cappozzo et al ., ). In M. grayi and M. hectori , this observation was made on immature to subadult specimens.…”

Far from home: Record of a vagrant striped dolphin in Patagonia with notes on diet, parasites and age determination

“…The Cestoda Tetrabothrius sp. are mainly found in pelagic cetaceans (Hoberg, 1987), although in Argentina it was found only in spectacled porpoise and Hector's beaked whale (Cappozo et al, 2005;Berón Vera et al, 2008) and in the present study. Molecular and morphological analyses are ongoing to determine the specific status of the parasites found in this work, especially because it is the first host record in this part of the striped dolphin' distribution.…”

Whales, Dolphins, and Other Marine Mammals of the World

“…In addition, species for which there is not enough information to do a proper illustration should not be showing up in the book in a manner suggesting that they are a well‐described species. For example, the Hector's beaked whale ( Mesoplodon hectori ) illustration does not match the current information on external appearance as described by Cappozzo et al . (2005).…”