摘要
Inadditiontoforwardundulatoryswimming,Gymnarchusniloticuscanswimviaundulationsofthedorsalfinwhilethebodyaxisremainsstraight;furthermore,itswimsforwardandbackwardinasimilarway,whichindicatesthattheundulationofthedorsalfincansimultaneouslyprovidebidirectionalpropulsiveandmaneuveringforceswiththehelpofthetailfin.Ahigh-resolutionCharge-CoupledDevice(CCD)imagingcamerasystemisusedtorecordkinematicsofsteadyswimmingaswellasmaneuveringinG.niloticus.Basedonexperimentaldata,thispaperdiscussesthekinematics(cruisingspeed,wavespeed,cyclefrequency,amplitude,lateraldisplacement)offorwardaswellasbackwardswimmingandmaneuvering.Duringforwardswimming,thepropulsiveforceisgeneratedmainlybyundulationsofthedorsalfinwhilethebodyaxisremainsstraight.Thekinematicparameters(wavespeed,wavelength,cyclefrequency,amplitude)havestatisticallysignificantcorrelationswithcruisingspeed.Inaddition,theyawattheheadisminimalduringsteadyswimming.Fromexperimentaldata,themaximallateraldisplacementofheadisnotmorethan1%ofthebodylength,whilethemaximallateraldisplacementofthewholebodyisnotmorethan5%ofthebodylength.AnotherimportantfeatureisthatG.niloticusswimsbackwardsusinganundulatorymechanismthatresemblestheforwardundulatoryswimmingmechanism.Inbackwardswimming,theincreaseoflateraldisplacementoftheheadiscomparativelysignificant;theamplitudeprofilesofthepropulsivewavealongthedorsalfinaresignificantlydifferentfromthoseinforwardswimming.WhenG.niloticusdoesfastmaneuvering,itsbodyisfirstbentintoeitheraCshapeoranSshape,thenitisrapidlyunwoundinatravellingwavefashion.Itrarelymaneuverswithoutthehelpofthetailfinandbodybending.
出版日期
2005年03月13日（中国期刊网平台首次上网日期，不代表论文的发表时间）
