Nectophore coordination and kinematics by physonect siphonophores

Area of Science:

• Marine Biology
• Animal Locomotion
• Fluid Dynamics

Background:

• Siphonophores are abundant pelagic organisms.
• Many siphonophores utilize multiple jets for propulsion.
• The kinematics and coordination of these jets are poorly understood.

Purpose of the Study:

• To investigate the kinematics of individual nectophores (swimming bells).
• To examine the coordination of adjacent nectophores during swimming.
• To understand how jet coordination impacts siphonophore locomotion.

Main Methods:

• Video recording of physonect siphonophore swimming behavior using ROVs and SCUBA.
• Quantification of pulsed kinematics of individual nectophores.
• Analysis of coordination between adjacent and opposite nectophores.

Main Results:

• Axially aligned nectophores on the same side pulsed metachronally.
• Coordination did not extend across the nectosome; no coordination between opposite sides.
• Metachronal waves typically initiated apically and traveled dorsally, except in Apolemia rubriversa.
• Opposite nectophore groups pulsed at similar frequencies, ensuring linear trajectories.

Conclusions:

• Siphonophore swimming involves metachronal coordination of nectophores on the same side.
• Lack of coordination between opposite sides is compensated by similar pulsing frequencies.
• Jet wake interactions and metachronal wave timing are crucial for efficient propulsion.