Date of Award

Spring 2024

Document Type


Degree Name

Doctor of Philosophy (PhD)


Biological Sciences


Ecological Sciences

Committee Director

Ian K. Bartol

Committee Member

Daniel J. Barshis

Committee Member

Michael Vecchione

Committee Member

John P. Whiteman

Committee Member

Paul S. Krueger


Turning is important for life underwater, playing roles in predator avoidance, prey capture, locomotion, and communication. While turning abilities have been explored in many taxa, little is known about maneuverability of cephalopods, such as cuttlefishes and squids. The objectives of this dissertation include: (1) quantifying the turning abilities of cuttlefish hatchlings and determining whether there are species-specific differences; (2) examining the turning capabilities of adult cuttlefishes, with the goal of comparing adult performance with that of conspecific hatchlings; and (3) quantifying how adult neritic squids perform turns to provide a broader context of maneuvering strategies in cephalopods. To investigate turning, swimming behaviors of hatchling/adult cuttlefishes (Sepia officinalis and Sepia bandensis) and adult squids (Doryteuthis pealeii and Illex illecebrosus) were recorded using high-speed videography, and kinematic parameters were analyzed. For cuttlefish studies, particle image velocimetry (hatchlings) and defocusing digital particle tracking velocimetry (adults) data were also collected along with video. Hatchling S. officinalis turned faster than hatchling S. bandensis, but both species completed equally tight turns. Orientation (arms-first or tail-first) did not have a significant effect on turning performance. Cuttlefish hatchlings consistently used multiple short jets for controlled turning, with jet mode I (isolated vortex rings) being 3-4 times more common than jet mode II (elongated jets with leading rings). Adult Sepia bandensis turned tightly but relatively slowly, relying primarily on short vortex ring jets, and adults outperformed conspecific hatchlings in angular velocity and turning radii. As with hatchlings, orientation did not have a significant effect on kinematic or hydrodynamic properties in adult cuttlefishes, and most turns were performed arms-first. Squid Illex illecebrosus completed faster but broader turns than D. pealeii. Both species were able to complete tighter turns when oriented arms-first versus tail first, and I. illecebrosus curled its arms more in the arms-first mode, which likely increased angular velocity through a reduction in moment of inertia. The neritic squids considered here exhibited similar overall turning performance to cuttlefishes, although cuttlefishes relied on shorter jets and demonstrated no orientation differences. This study advances our understanding of turning capabilities of cuttlefishes throughout ontogeny and broadens our understanding of turning performance of squids.


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