Department of Biology, Amherst College, Amherst, MA 01002, USA.
Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, MA 01003, USA.
J Exp Biol. 2020 Aug 4;223(Pt 15):jeb219873. doi: 10.1242/jeb.219873.
Sexual selection can result in an exaggerated morphology that constrains locomotor performance. We studied the relationship between morphology and the tail-flip escape response in male and female rusty crayfish (), a species in which males have enlarged claws (chelae). We found that females had wider abdomens and longer uropods (terminal appendage of the tail fan) than males, while males possessed deeper abdomens and larger chelae, relative to total length. Chelae size was negatively associated with escape velocity, whereas longer abdomens and uropods were positively associated with escape velocity. We found no sex-specific differences in maximum force generated during the tail flip, but uropod length was strongly, positively correlated with tail-flip force in males. Particle image velocimetry (PIV) revealed that the formation of a vortex, rather than the expulsion of fluid between two closing body surfaces, generates propulsion in rusty crayfish. PIV also revealed that the pleopods (ventral abdominal appendages) contribute to the momentum generated by the tail. To our knowledge, this is the first confirmation of vortex formation in a decapod crustacean.
性选择会导致形态夸张，从而限制运动性能。我们研究了形态与雄性和雌性铁锈红螯虾（）的尾部翻转逃避反应之间的关系，在这种物种中，雄性有较大的爪子（螯）。我们发现，与总长度相比，雌性的腹部更宽，尾扇的尾肢（末端附属物）更长，而雄性的腹部更深，螯更大。螯的大小与逃避速度呈负相关，而较长的腹部和尾肢与逃避速度呈正相关。我们没有发现雄性和雌性在尾部翻转过程中产生的最大力方面存在性别特异性差异，但在雄性中，尾肢长度与尾翻转力呈强正相关。粒子图像测速（PIV）显示，在铁锈红螯虾中，产生推进力的是涡的形成，而不是两个闭合体表面之间的流体排出。PIV 还显示，腹肢（腹部的腹侧附属物）有助于尾部产生的动量。据我们所知，这是首次确认在十足甲壳动物中形成涡。
