Kinematics of swimming and thrust production during powerstroking bouts of the swim frenzy in green turtle hatchlings

Booth, David T. (2014) Kinematics of swimming and thrust production during powerstroking bouts of the swim frenzy in green turtle hatchlings. Biology Open, 3 10: 887-894. doi:10.1242/bio.20149480


Author Booth, David T.
Title Kinematics of swimming and thrust production during powerstroking bouts of the swim frenzy in green turtle hatchlings
Journal name Biology Open   Check publisher's open access policy
ISSN 2046-6390
Publication date 2014-10-01
Year available 2014
Sub-type Article (original research)
DOI 10.1242/bio.20149480
Open Access Status DOI
Volume 3
Issue 10
Start page 887
End page 894
Total pages 8
Place of publication Cambridge, United Kingdom
Publisher The Company of Biologists
Collection year 2015
Language eng
Formatted abstract
Hatchling sea turtles emerge from nests, crawl down the beach and enter the sea where they typically enter a stereotypical hyperactive swimming frenzy. During this swim the front flippers are moved up and down in a flapping motion and are the primary source of thrust production. I used high-speed video linked with simultaneous measurement of thrust production in tethered hatchlings, along with high-speed video of free swimming hatchlings swimming at different water speeds in a swim flume to investigate the links between kinematics of front flipper movement, thrust production and swimming speed. In particular I tested the hypotheses that (1) increased swimming speed is achieved through an increased stroke rate; (2) force produced per stroke is proportional to stroke amplitude, (3) that forward thrust is produced during both the down and up phases of stroking; and (4) that peak thrust is produced towards the end of the downstroke cycle. Front flipper stroke rate was independent of water speed refuting the hypothesis that swimming speed is increased by increasing stroke rate. Instead differences in swimming speed were caused by a combination of varying flipper amplitude and the proportion of time spent powerstroking. Peak thrust produced per stroke varied within and between bouts of powerstroking, and these peaks in thrust were correlated with both flipper amplitude and flipper angular momentum during the downstroke supporting the hypothesis that stroke force is a function of stroke amplitude. Two distinct thrust production patterns were identified, monophasic in which a single peak in thrust was recorded during the later stages of the downstroke, and biphasic in which a small peak in thrust was recorded at the very end of the upstroke and this followed by a large peak in thrust during the later stages of the downstroke. The biphasic cycle occurs in ∼20% of hatchlings when they first started swimming, but disappeared after one to two hours of swimming. The hypothesis that forward thrust is produced during both the up and down stroke was only supported relatively rarely in hatchlings that exhibited the diphasic cycle, the majority of time forward thrust was only produced during the downstroke phase. The hypothesis that peak forward thrust is produced during the end of the downstroke was supported in both the monophasic and biphasic thrust producing stroke cycles.
Keyword Swimming
Kinematics
Thrust
Hatchlings
Sea turtle
Green turtle
Frenzy swim
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Biological Sciences Publications
 
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