Vi. Arreola et Mw. Westneat, MECHANICS OF PROPULSION BY MULTIPLE FINS - KINEMATICS OF AQUATIC LOCOMOTION IN THE BURRFISH (CHILOMYCTERUS-SCHOEPFI), Proceedings - Royal Society. Biological Sciences, 263(1377), 1996, pp. 1689-1696
Locomotion in tetraodontiform fishes (puffers and relatives) involves
the use of multiple fins for propulsion during swimming. A variety of
tertraodontiform swimming modes have been defined, but the contributio
ns of pectoral, dorsal, anal, and caudal fins to the propulsion in the
se fish remain largely unknown. We used video analysis to study swimmi
ng behaviour of the striped burrfish (Chilomycterus schoepfi). Burrfis
h swam in a flow tank at speeds of 0.5-6.3 standard body lengths per s
econd, during which all fins oscillated at all speeds. The oscillation
frequency range of all fins was 2.1-9.2 Hz, increasing with velocity.
Pectoral fins were always out of phase, usually by 180 degrees (alter
nate left and right beats). Reduced frequency parameters for all fins
were high (0.65-12.1) indicating that acceleration reaction is the dom
inant mechanism of thrust. Phase lag between anal and caudal fins assu
med three distinct states which suggests that burrfishes alter the pat
terns of fin motion in discrete stages analogous to gaits. Rapid oscil
lation of five fins in various degrees of asynchrony is a mechanism to
produce relatively constant thrust from multiple periodic motions.