Embodied postural dynamics underlie behavioral diversity in a benthic sessile chordate.

Area of Science:

• Marine Biology
• Animal Behavior
• Chordate Zoology

Background:

• Sessile benthic animals are often presumed to have limited behavioral repertoires due to their immobility and simple nervous systems.
• The behavioral complexity of basal chordates, particularly those with a sessile adult stage, remains largely unexplored.

Purpose of the Study:

• To comprehensively characterize the spontaneous and stimulus-evoked behaviors of adult Ciona intestinalis.
• To investigate the organization and modularity of behavioral responses in a sessile chordate.

Main Methods:

• Utilized time-lapse imaging and markerless pose estimation to capture detailed kinematic data.
• Applied dimensionality reduction techniques (e.g., 'eigencionas') and spatiotemporal embedding to analyze postural variance.
• Employed Hidden Markov Modeling to understand behavioral state transitions in response to stimuli.

Main Results:

• Identified three distinct postural engagement states in Ciona intestinalis, defined by configuration, kinematics, and temporal dynamics.
• Demonstrated that mechanical, hydrodynamic, and chemical stimuli elicit context-specific sensorimotor responses and motor patterns.
• Uncovered 16 stereotyped behavioral modules organized within a shared state space, modulated by external cues.

Conclusions:

• Adult Ciona intestinalis possesses a rich and modular behavioral repertoire, challenging previous assumptions about sessile organisms.
• Behavioral states and modules are dynamically reorganized by environmental stimuli, indicating sophisticated sensory processing and motor control.
• This study provides novel insights into the evolution of behavioral complexity in early chordates.