Tomita Taketeru, Toda Minoru, Miyamoto Kei, Oka Shin-Ichiro, Ueda Keiichi, Sato Keiichi
Hokkaido University Museum, Hakodate, Hokkaido, Japan.
Okinawa Churashima Research Center, Okinawa Churashima Foundation, Motobu, Okinawa, Japan.
Anat Rec (Hoboken). 2018 Jun;301(6):1068-1073. doi: 10.1002/ar.23776. Epub 2018 Jan 22.
The lunate-shaped caudal fin in lamnid sharks is a morphological specialization for their thunniform mode of locomotion, but its developmental process during gestation has been poorly investigated. Observations of 21 embryonic specimens of the white shark (Carcharodon carcharias) revealed that their caudal fin morphology drastically changes from strongly heterocercal to lunate-shaped through ontogeny. This morphological change involves (1) rapid elongation of the ventral lobe, (2) increased upward curvature of the vertebra within the caudal fin, and (3) formation of keels at both lateral sides of the caudal fin base. These morphological changes are probably shared among the members of the family Lamnidae and are in contrast with the developmental process of the heterocercal tail in the lamniform Carcharias taurus, in which the caudal fin morphology is almost unchanged through the late gestation period. Anat Rec, 301:1068-1073, 2018. © 2018 Wiley Periodicals, Inc.
鼠鲨科鲨鱼的新月形尾鳍是其典型的游泳模式的一种形态特化，但在妊娠期其发育过程却鲜有研究。对21只大白鲨（噬人鲨）胚胎样本的观察显示，它们的尾鳍形态在个体发育过程中从强烈的歪尾型急剧转变为新月形。这种形态变化包括：（1）腹叶迅速伸长；（2）尾鳍内椎骨向上弯曲增加；（3）在尾鳍基部两侧形成龙骨。这些形态变化可能在鼠鲨科成员中普遍存在，并且与鼠鲨目皱唇鲨的歪尾型尾巴的发育过程形成对比，在皱唇鲨中，尾鳍形态在妊娠后期几乎没有变化。《解剖学记录》，301:1068 - 1073，2018年。© 2018威利期刊公司。
