Pectoral fin of the megamouth shark: skeletal and muscular systems, skin histology, and functional morphology.
This is the first known report on the skeletal and muscular systems, and the skin histology, of the pectoral fin of the rare planktivorous megamouth shark Megachasma pelagios. The pectoral fin is characterized by three features: 1) a large number of segments in the radial cartilages; 2) highly elastic pectoral fin skin; and 3) a vertically-rotated hinge joint at the pectoral fin base. These features suggest that the pectoral fin of the megamouth shark is remarkably flexible and mobile, and that this flexibility and mobility enhance dynamic lift control, thus allowing for stable swimming at slow speeds. The flexibility and mobility of the megamouth shark pectoral fin contrasts with that of fast-swimming sharks, such as Isurus oxyrhinchus and Lamna ditropis, in which the pectoral fin is stiff and relatively immobile.
Hokkaido University Museum, Hakodate, Hokkaido, Japan ; Department of Geology, University of California Davis, Davis, California, United States of America.
Taketeru
T
Tomita
School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan.
Sho
S
Tanaka
Okinawa Churashima Research Center, Okinawa Churashima Foundation, Motobu, Okinawa, Japan.
Keiichi
K
Sato
Hokkaido University, Hakodate, Hokkaido, Japan.
Kazuhiro
K
Nakaya
D058500:Animal Fins / Q000166:cytology* / Q000502:physiology*; D000818:Animals; D005121:Extremities / Q000502:physiology; D009141:Musculoskeletal System / Q000166:cytology* / Q000503:physiopathology*; D012754:Sharks / Q000502:physiology*; D012867:Skin / Q000166:cytology*; D013550:Swimming / Q000502:physiology