Embryology of Dolphins

Stĕrba, O; Klima, Milan; Schildger, Bernd

doi:10.1007/978-3-642-57297-5

Cited by 11 publications

(20 citation statements)

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“…Another potential source of error in utilizing blubber progesterone levels to determine pregnancy, is the timing of the elevation and decline in blubber progesterone with respect to commencement and termination of pregnancy. In our study, we observed that in embryos with total lengths <1 cm or approximately 2–3 wk postconception (Šterba et al 2000), blubber progesterone levels were between 183 and 248 ng/g, well within the total range we see for females with larger fetuses and much higher than those found in non‐pregnant animals. This suggests that progesterone levels rise quickly in the blubber at the commencement of pregnancy.…”

Section: Discussionsupporting

confidence: 81%

Determining Pregnancy From Blubber in Three Species of Delphinids

Kellar¹,

Trego²,

Marks³

et al. 2006

Marine Mammal Science

120

158

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We quantified progesterone in 110 blubber samples from dolphins of known reproductive status in order to test the accuracy of a method to determine pregnancy status in wild cetaceans. The samples were collected from fishery‐bycaught delphinids of three species (Delphinus delphis, Lissodelphis borealis, and Lagenorhynchus obliquidens). We ascertained that blubber progesterone concentrations could clearly distinguish pregnant D. delphis (range 132–415 ng/g, mean 261 ng/g) from non‐pregnant mature and immature ones (range 0.92–48.2 ng/g, mean 15.2 ng/g). We found similar dramatic differences in L. borealis and L. obliquidens. These results were insensitive to various blubber sampling depths and anatomical sampling locations on the body, suggesting relative homogeneity of progesterone levels throughout the blubber. However, no trend was found in blubber progesterone concentration with fetal length, indicating that although blubber progesterone appears to distinguish pregnancy status, it is unlikely to differentiate pregnancy stage. Based on the findings presented here we suggest that this method, when coupled with projectile biopsy procedures, can be used to assess the pregnancy status of free‐ranging cetaceans and thus provide a new tool to determine pregnancy rates of wild populations.

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Section: Discussionsupporting

confidence: 81%

Determining Pregnancy From Blubber in Three Species of Delphinids

Kellar¹,

Trego²,

Marks³

et al. 2006

Marine Mammal Science

120

158

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“…1). All of these features are obvious in our perinatal specimens and are characteristic for stage S 11 in the ontogenetic classification system of Štěrba et al (2000) but also for neonatal dolphins. In general, the head of the perinatal Pacific spotted dolphin is rather similar morphologically to that of the adult and reflects the precocial developmental state of these animals.…”

Section: Resultssupporting

confidence: 66%

“…Whereas cetacean embryos largely show plesiomorphic characters also seen in other mammals of the same developmental age (Oelschläger and Buhl, 1985a, b; Oelschläger et al, 1987; Buhl and Oelschläger, 1988; Oelschläger and Kemp, 1998; Klima, 1999; Štěrba et al, 2000; Richardson and Oelschläger, 2002), early fetal stages illustrate the transition from the eutherian bauplan to cetacean organization (e.g., the realization of an uncoupled ear complex and a beak‐like larynx; Fig. 10).…”

Section: Discussionmentioning

confidence: 95%

“…In contrast, the literature on the prenatal anatomy of the head in these animals is comparatively sparse (cf. Reidenberg and Laitman, 2002), and yet development can provide most valuable insights into the morphological details of cetacean evolution (Wanke, 1990; Sedmera et al, 1997a, b, 2003; Klima, 1999; Štěrba et al, 2000; Kinkel et al, 2001; Richardson and Oelschläger, 2002).…”

Section: The Specimens Examined In This Studymentioning

confidence: 99%

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Head morphology in perinatal dolphins: A window into phylogeny and ontogeny

Rauschmann¹,

Huggenberger

Kossatz

et al. 2006

Journal of Morphology

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In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes.

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“…Early in development, the heads of cetacean embryos closely resemble those of other mammals at similar developmental stages, but they begin to acquire more typical cetacean shapes in the late embryonic and early fetal stages (Gill, ; Štěrba et al, ; Thewissen and Heyning, ; Roston et al, ). This observation is consistent with the finding that early stages of facial development are conserved throughout tetrapods (Young et al, ).…”

Section: Biology Of Telescoping: An Overviewmentioning

confidence: 99%

Cetacean Skull Telescoping Brings Evolution of Cranial Sutures into Focus

Roston

Roth

2019

The Anatomical Record

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Many modifications to the mammalian bauplan associated with the obligate aquatic lives of cetaceans—fusiform bodies, flukes, flippers, and blowholes—are evident at a glance. But among the most strikingly unusual and divergent features of modern cetacean anatomy are the arrangements of their cranial bones: (1) bones that are situated at opposite ends of the skull in other mammals are positioned close together, their proximity resulting from (2) these bones extensively overlapping the bones that ordinarily would separate them. The term “telescoping” is commonly used to describe the odd anatomy of modern cetacean skulls, yet its usage and the particular skull features to which it refers vary widely. Placing the term in historical and biological context, this review offers an explicit definition of telescoping that includes the two criteria enumerated above. Defining telescoping in this way draws attention to many specific biological questions that are raised by the unusual anatomy of cetacean skulls; highlights the central role of sutures as the locus for changes in the sizes, shapes, mechanical properties, and connectivity of cranial bones; and emphasizes the importance of sutures in skull development and evolution. The unusual arrangements of cranial bones and sutures referred to as telescoping are not easily explained by what is known about cranial development in more conventional mammals. Discovering the evolutionary‐developmental processes that produce the extensive overlap characteristic of cetacean telescoping will give insights into both cetacean evolution and the “rules” that more generally govern mammalian skull function, development, and evolution. Anat Rec, 302:1055–1073, 2019. © 2019 Wiley Periodicals, Inc.

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Embryology of Dolphins

Cited by 11 publications

References 0 publications

Determining Pregnancy From Blubber in Three Species of Delphinids

Determining Pregnancy From Blubber in Three Species of Delphinids

Head morphology in perinatal dolphins: A window into phylogeny and ontogeny

Cetacean Skull Telescoping Brings Evolution of Cranial Sutures into Focus

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