Date of Award

Spring 2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Director

Ian Bartol

Committee Member

Shirel Kahane-Rapport

Committee Member

Gloria Massamba N’Siala

Abstract

Upon hatching, squid paralarvae must become proficient at locomotion and prey capture before their yolk reserves are depleted, while also contending with the physical constraints associated with low/intermediate Reynolds number (Re) environments. Although some aspects of behavior and jet dynamics have been examined in squids during early ontogeny, little is known about routine behaviors in paralarvae, whether repeatable patterns are employed, or how these behaviors are achieved dynamically. To better understand swimming behaviors and the propulsive flows that drive them in paralarvae, high-speed video data and digital particle image velocimetry (DPIV) data were collected simultaneously from longfin squid Doryteuthis pealeii paralarvae swimming in a viewing chamber. A catalog of repeated behaviors (ethogram) was created along with transition probability matrices, behavioral breakdowns, and a kinematic diagram. Jet properties, such as impulse (I) and angular impulse (A), mean and maximum jet velocity (Ujave and Ujmax, respectively), and jet length-to-diameter ratios based on the vorticity extent (Lω/Dω), were also determined. Doryteuthis pealeii paralarvae displayed 14 different action patterns. Of these behaviors, short vertical jets (SVJ) and sinking (SK) were employed most frequently, often in sequence for station-holding. Several behaviors, such as bell swings (BS), spirals (SR), and somersaults (SM), occurred over long periods in succession, while other behaviors, such as swoops (SW), arm tucks (AT), and pirouettes (PR), were rare. For those behaviors with quantifiable flow fields (50% of behaviors), jet flows ranged from isolated vortex rings to longer regions of vorticity with and without leading-edge vortex rings. Significant body induced vorticity was associated with many of the behaviors. Powerful tail-first escape jets, termed sprints (ST), exhibited higher impulse (I) and angular impulse (A) than several lower amplitude jet behaviors, such as BS, SVJ, and TFJ. In addition, ST behaviors exhibited significantly greater Lω/Dω than curves (CV) and a trend in higher Lω/Dω relative to the other behavioral categories. While not statistically significant, the BS behavior was associated with a clear pattern of lower Ujave and Ujmax compared to the other behaviors. Collectively, my project provides important insights into how squid behave and locomote during a critical early stage of development.

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DOI

https://doi.org/10.25777/s165-nz60

ISBN

9798197810571

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