Functional morphology of the gills of the shortfin mako, Isurus oxyrinchus, a lamnid shark

Nicholas C. Wegner, Chugey A. Sepulveda, Kenneth Olson, Kelly A. Hyndman, Jeffrey B. Graham

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

This study examines the functional gill morphology of the shortfin mako, Isurus oxyrinchus, to determine the extent to which its gill structure is convergent with that of tunas for specializations required to increase gas exchange and withstand the forceful branchial flow induced by ram ventilation. Mako gill structure is also compared to that of the blue shark, Prionace glauca, an epipelagic species with lower metabolic requirements and a reduced dependence on fast, continuous swimming to ventilate the gills. The gill surface area of the mako is about one-half that of a comparably sized tuna, but more than twice that of the blue shark and other nonlamnid shark species. Mako gills are also distinguished from those of other sharks by shorter diffusion distances and a more fully developed diagonal blood-flow pattern through the gill lamellae, which is similar to that found in tunas. Although the mako lacks the filament and lamellar fusions of tunas and other ram-ventilating teleosts, its gill filaments are stiffened by the elasmobranch interbranchial septum, and the lamellae appear to be stabilized by one to two vascular sacs that protrude from the lamellar surface and abut sacs of adjacent lamellae. Vasoactive agents and changes in vascular pressure potentially influence sac size, consequently effecting lamellar rigidity and both the volume and speed of water through the interlamellar channels. However, vascular sacs also occur in the blue shark, and no other structural elements of the mako gill appear specialized for ram ventilation. Rather, the basic elasmobranch gill design and pattern of branchial circulation are both conserved. Despite specializations that increase mako gill area and efficacy relative to other sharks, the basic features of the elasmobranch gill design appear to have limited selection for a larger gill surface area, and this may ultimately constrain mako aerobic performance in comparison to tunas.

Original languageEnglish
Pages (from-to)937-948
Number of pages12
JournalJournal of Morphology
Volume271
Issue number8
DOIs
StatePublished - Aug 2010

Fingerprint

Isurus oxyrinchus
Sharks
sharks
gills
Tuna
Prionace glauca
tuna
Elasmobranchii
blood vessels
rams
Blood Vessels
Ventilation
surface area

Keywords

  • Blue shark
  • Diffusion distance
  • Gill surface area
  • Interbranchial septum
  • Lamnid-tuna convergence
  • Ram ventilation

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Developmental Biology
  • Medicine(all)

Cite this

Functional morphology of the gills of the shortfin mako, Isurus oxyrinchus, a lamnid shark. / Wegner, Nicholas C.; Sepulveda, Chugey A.; Olson, Kenneth; Hyndman, Kelly A.; Graham, Jeffrey B.

In: Journal of Morphology, Vol. 271, No. 8, 08.2010, p. 937-948.

Research output: Contribution to journalArticle

Wegner, Nicholas C. ; Sepulveda, Chugey A. ; Olson, Kenneth ; Hyndman, Kelly A. ; Graham, Jeffrey B. / Functional morphology of the gills of the shortfin mako, Isurus oxyrinchus, a lamnid shark. In: Journal of Morphology. 2010 ; Vol. 271, No. 8. pp. 937-948.
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