Functional myology of the harbour porpoise, <i>Phocoena phocoena</i> (L.)

Smith, G. J. D.; Browne, K. W.; Gaskin, D. E.

doi:10.1139/z76-083

Cited by 33 publications

(29 citation statements)

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“…Unlike most other mammals, cetaceans are obligate axial locomotors: they swim by the alternate action of their robust vertebral and abdominal muscles. The down stroke is powered by both the hypaxial and abdominal muscles (Arkowitz and Rommel, 1985;Pabst, 1989;Pilleri et al, 1976;Smith et al, 1976). These muscles define the roof and floor of the cetacean abdominal cavity (Fig.…”

Section: Potential Limits To Convective Heat Loss: Circulatory Changementioning

confidence: 99%

Functional morphology of the vascular plexuses associated with the cetacean uterus

1993

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The cetacean reproductive system is surrounded by thermogenic locomotory muscle and insulating blubber. This arrangement suggests elevated temperatures at the uterus that could induce detrimental effects on fetal development. We present anatomical evidence for a complex countercurrent heat exchange system that could function to regulate the thermal environment of the uterus and a developing fetus. Cooled venous blood from the surfaces of the dorsal fin and flukes enters the abdominal cavity via the lumbo-caudal venous plexus. This plexus is juxtaposed to the arterial and venous plexuses associated with the uterus. The morphology of the lumbo-caudal venous plexus suggests that it acts as a "heat sink" for the adjacent tissues. Heat may be transferred to the cool, lumbo-caudal venous plexus from the warm blood in the arterial and venous plexuses supplying the uterus. Heat may also be transferred from adjacent locomotory muscles to the cool lumbo-caudal venous plexus. The countercurrent heat exchanger created by the juxtaposition of the lumbo-caudal venous plexus with the uterovarian arterial plexus is similar in design to that of the countercurrent heat exchanger described for male cetaceans. The functional implications of introducing cool superficial blood into the abdominal cavity of a diving, and locomoting female cetacean are discussed.

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Section: Potential Limits To Convective Heat Loss: Circulatory Changementioning

confidence: 99%

Functional morphology of the vascular plexuses associated with the cetacean uterus

1993

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“…Porpoises are the smallest cetaceans, and some have reported swimming speeds of approximately 1.5 m/s. Their broad flippers generate lift and drag, facilitating surfacing maneuvers (Smith et al, 1976). The harbor porpoise (Phocoena phocoena) flippers contribute to 18% of the total hydrodynamic drag, but they are only 4% of the body area (Woodward et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The harbor porpoise (Phocoena phocoena) flippers contribute to 18% of the total hydrodynamic drag, but they are only 4% of the body area (Woodward et al, 2006). Empirical data on wild harbor porpoises have shown that the flippers are positioned into lift-generating orientations (symmetrical dorsal rotation of the leading edge of the flippers) just prior to surfacing, but during swimming maneuvers, the flippers are usually positioned against the body (Smith et al, 1976), thus reducing drag. Although data suggest that porpoise flippers function as a standard cetacean flipper, their anatomical structure and development are unique.…”

Section: Introductionmentioning

confidence: 99%

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (<I>Phocoena sinus</I>)

Mellor¹,

Cooper²,

Torre³

et al. 2009

aquatic mammals

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Heterochrony, the change in timing of developmental processes, is thought to be a key process shaping the numerous limb morphologies of tetrapods. Through a delayed offset in digit development, all cetaceans (i.e., whales, dolphins, and porpoises) have evolved supernumary phalanges (hyperphalangy). Moreover, some toothed cetaceans further alter digital morphologies by delayed endochondral and perichondral ossification of individual elements. In the harbor porpoise (Phocoena phocoena), these paedomorphic patterns have created poorly ossified phalangeal elements. However, no studies have addressed this morphology in other porpoise taxa. This study documents the timing of carpal and digital epiphyseal ossification in the poorly studied vaquita (Phocoena sinus) based on radiographs (n = 18) of known-age specimens. Patterns of vaquita manus ossification were compared between other porpoise and delphinid taxa. Adult vaquitas are paedomorphic in carpal, metacarpal, and digital development as they maintain a juvenile ossification pattern relative to that of other porpoise species of equivalent ages. Vaquitas also ossify fewer carpal elements as compared to other porpoise and some delphinid cetaceans, and ossification arrests relative to that of the harbor porpoise. Vaquitas also display sexual dimorphism as females reach a greater body size and display more ossified elements in the manus relative to their paedomorphic male cohorts.

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“…In the only published kinematic analysis of surfacing behavior in any cetacean, a wild harbor porpoise ( Phocoena phocoena ) was observed to approach the surface at an oblique angle and simultaneously ventrally flex its caudal tailstock and dorsally flex its head prior to expiration (Smith et al, 1976). Once the head was above the surface of the water, it was immediately flexed ventrally and inspiration occurred (Smith et al, 1976).…”

Section: Discussionmentioning

confidence: 99%

“…Although, a small number of anatomical descriptions have been conducted on other cetaceans [e.g., Balaenoptera acutorostrata (Carte and Macalister, 1868), Grampus griseus (Murie, 1871), Kogia breviceps (Schulte and Smith, 1918), Neophocaena phocaenoides (Howell, 1927), Monodon monoceros (Howell, 1930), Phocoena phocoena (Slijper, 1936; Smith et al, 1976), Pontoporia blainvillei (Strickler, 1978)], these studies either do not mention or do not describe in detail muscles used for ventilation. To date, only Dearolf (2002, 2003) has examined a ventilatory muscle, the diaphragm, in a bottlenose dolphin.…”

mentioning

confidence: 99%

The gross morphology and histochemistry of respiratory muscles in bottlenose dolphins, Tursiops truncatus

Cotten

Piscitelli

McLellan

et al. 2008

Journal of Morphology

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Most mammals possess stamina because their locomotor and respiratory (i.e., ventilatory) systems are mechanically coupled. These systems are decoupled, however, in bottlenose dolphins (Tursiops truncatus) as they swim on a breath-hold. Locomotion and ventilation are coupled only during their brief surfacing event, when they respire explosively (up to 90% of total lung volume in approximately 0.3s) (Ridgway et al., 1969). The predominantly slow-twitch fiber profile of their diaphragm (Dearolf, 2003) suggests that this muscle does not likely power their rapid ventilatory event. Based upon Bramble's (1989) biomechanical model of locomotor-respiratory coupling in galloping mammals, it was hypothesized that locomotor muscles function to power ventilation in bottlenose dolphins. It was further hypothesized that these muscles would be composed predominantly of fast-twitch fibers to facilitate the bottlenose dolphin's rapid ventilation. The gross morphology of cranio-cervical (scalenus, sternocephalicus, sternohyoid), thoracic (intercostals, transverse thoracis), and lumbo-pelvic (hypaxialis, rectus abdominis, abdominal obliques) muscles (n=7) and the fiber-type profiles (n=6) of selected muscles (scalenus, sternocephalicus, sternohyoid, rectus abdominis) of bottlenose dolphins were investigated. Physical manipulations of excised thoracic units were carried out to investigate potential actions of these muscles. Results suggest that the cranio-cervical muscles act to draw the sternum and associated ribs cranio-dorsally, which flares the ribs laterally, and increases the thoracic cavity volume required for inspiration. The lumbo-pelvic muscles act to draw the sternum and caudal ribs caudally, which decreases the volumes of the thoracic and abdominal cavities required for expiration. All muscles investigated were composed predominantly of fast-twitch fibers (range 61-88% by area) and appear histochemically poised for rapid contraction. These combined results suggest that dolphins utilize muscles, similar to those used by galloping mammals, to power their explosive ventilation.

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Functional myology of the harbour porpoise, Phocoena phocoena (L.)

Cited by 33 publications

References 0 publications

Functional morphology of the vascular plexuses associated with the cetacean uterus

Functional morphology of the vascular plexuses associated with the cetacean uterus

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (<I>Phocoena sinus</I>)

The gross morphology and histochemistry of respiratory muscles in bottlenose dolphins, Tursiops truncatus

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