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Heart and aorta morphology of the deep-diving hooded seal (Cystophora cristata)

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Abstract:



An investigation of the heart morphology of 8 male and 15 female hooded seals (Cystophora cristata) revealed that the heart is proportionately large and the aortic bulb is larger than that reported for most seals. Hooded seals of all ages have large hearts (0.64% of the body mass) and the right ventricle is proportionately longer and more muscular than reported for other seals. The bulb of the ascending aorta shows the large-diameter characteristic of seals capable of making long deep dives, and is constricted to a diameter of less than one-third in the descending aorta. In addition, the ascending aorta has a much greater concentration of elastin fibers than does the descending aorta. In combination with the large right ventricle, these features probably serve to increase lung perfusion during the hooded seal's surface recovery, and to maintain a high blood pressure throughout the cardiac cycle during diving bradycardia. That there was no substantive difference in the heart morphology of pups, yearlings, and adults, suggests that these features are important in the development of diving behavior, and agrees with the rapid behavioral and physiological development of hooded seal neonates.

L'étude de la morphologie du coeur de 8 mâles et de 15 femelles du phoque à capuchon (Cystophora cristata) a révélé que le coeur est gros proportionnellement au reste du corps et que le bulbe aortique est plus gros que celui qui est signalé chez la plupart des phoques. Les phoques à capuchon de tous âges ont un gros coeur (0,64 % de leur masse totale) et leur ventricule droit est proportionnellement plus long et plus musculaire que celui des autres phoques. Le bulbe de l'aorte ascendante a un grand diamètre, un caractère typique des phoques qui font des plongées profondes de longue durée, et il comporte une constriction dont le diamètre est moins du tiers de la valeur la plus grande dans l'aorte descendante. De plus, l'aorte ascendante a une concentration d'élastine beaucoup plus grande que celle que l'on trouve dans l'aorte descendante. Combinées au ventricule droit, qui est de grande taille, ces structures contribuent probablement à augmenter la perfusion du poumon du phoque à capuchon à son retour en surface et à maintenir élevée sa tension artérielle pendant tout le cycle cardiaque lors d'une bradycardie de plongée. L'absence de différences importantes entre la morphologie du coeur des jeunes phoques et celle des phoques de 1 an ou des adultes indique que ces caractères sont importants pour le développement du comportement de plongée et elle est compatible avec la rapidité du développement comportemental et physiologique des phoques à capuchon nouveau-nés.[Traduit par la Rédaction]

Document Type: Research Article

Publication date: 2002-11-01

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  • Published since 1929, this monthly journal reports on primary research contributed by respected international scientists in the broad field of zoology, including behaviour, biochemistry and physiology, developmental biology, ecology, genetics, morphology and ultrastructure, parasitology and pathology, and systematics and evolution. It also invites experts to submit review articles on topics of current interest.
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