This study examined cardiovascular adjustments in the invasive land snail Cornu aspersum under two behavioral states: experimentally induced retraction and active locomotion. Using a custom laser optocardiography system to visualize cardiac movements through the shell, the authors quantified heart rate and heart rate variability (HRV) from mechanical oscillations. They report an increase in heart rate from retracted to moving states, accompanied by altered HRV and fewer cardiac irregularities during movement. Locomotion intensity and body-size measures did not influence the cardiac parameters measured. The results are discussed in the context of metabolic demand, neural regulation, and behaviorally induced mechanical constraints on the circulatory system.
Physiological and behavioral flexibility are central to survival in changing environments. Vertebrate fight-or-flight responses include rapid cardiac adjustments to meet elevated metabolic demands; invertebrates also demonstrate cardiovascular modulation during escape behaviors despite lower baseline metabolic rates. Terrestrial gastropods characteristically retract into their shells as a passive antipredator response, which could depress cardiovascular function, yet some snails exhibit more active escape behaviors.
The authors aimed to compare heart activity in Cornu aspersum between retracted and moving states. They hypothesized that movement would increase energetic demands of the foot and therefore require higher hemolymph recirculation reflected by higher heart rate and more regular cardiac activity. They also tested whether locomotor speed and body size affected cardiovascular responses.
Collection and maintenance
Adult Cornu aspersum individuals were collected from urban gardens in western Bogotá, Colombia (approximate coordinates reported in the manuscript). Snails were identified by standard shell coloration and banding patterns, held in a laboratory aquarium under controlled temperature (~21.3 ± 0.8°C), relative humidity (~62 ± 5%), and an approximate 12 h:12 h light–dark cycle. Snails were fed Batavia lettuce and provided with a calcium supplement; they acclimated for at least one month. Food was removed the night before experiments to avoid postprandial effects on heart rate.
Body-size characterization
Body-size proxies included total mass (MassT: shell + soft tissue), isolated shell mass, dehydrated soft-tissue (dry) mass, and shell height and diameter measured with a digital caliper. MassT was recorded prior to cardiac recordings. After experiments, snails were euthanized via immersion in liquid nitrogen for 60 seconds, dissected to separate soft tissue from shell, dehydrated at 60°C for 48 hours, and then weighed to obtain dry-tissue mass.
Optocardiographic recordings
Cardiac movements were visualized by holding snails vertically in a graduated clamp cushioned with rubber tips to prevent shell damage. A convergent pair of lasers — green (532 nm) and red (632 nm) — were directed above the shell to permit direct observation of heart activity through the intact shell. The laser assembly and camera permitted recording of oscillatory contractions and relaxations of cardiac cavities within a single visual plane. From these mechanical recordings, heart rate and metrics of heart rate variability (HRV) and cardiac regularity were extracted using imaging analyses described in the manuscript.
Experimental conditions
Each snail was recorded in two behavioral conditions: (1) experimentally induced retraction and (2) moving (locomotion). Locomotor intensity (speed) was quantified to assess correlations with heart parameters. The manuscript reports detailed recording and analysis procedures in the methods and supporting information.
Heart rate and HRV across behavioral states
The principal finding is that heart rate increased when snails transitioned from the retracted state to the moving state. This increase was associated with changes in heart rate variability and a reduction in cardiac irregularities during movement. Thus, movement corresponded to a faster and more regular mechanical cardiac rhythm compared with the retracted condition.
Effects of locomotion intensity and body size
Contrary to one of the initial predictions, locomotor intensity (movement speed) did not influence heart rate or HRV in the data presented. Likewise, body-size metrics (including total mass, shell mass, dry soft-tissue mass, and shell dimensions) did not show effects on the cardiac parameters measured under the conditions tested.
Methods-related observations
The optocardiography approach using converging 532 nm and 632 nm lasers provided a noninvasive visualization of heart mechanics through the shell, enabling quantification of both rate and regularity from mechanical oscillations.
The authors interpret the observed increase in heart rate and enhanced regularity during movement as reflecting combined influences of elevated metabolic demand of the foot, neural regulation of cardiac function, and behaviorally induced mechanical shifts in the circulatory system when the body extends from the shell. The reduction in cardiac irregularities during movement suggests a state-dependent stabilization of cardiac rhythm analogous to vertebrate fight-or-flight cardiovascular adjustments, even though anatomical autonomic control differs in invertebrates.
The absence of detectable effects of locomotor speed and body size on heart rate and HRV suggests that, for the range of movement intensities and sizes sampled, behavioral state (retracted vs. moving) is the dominant factor modifying cardiac function in Cornu aspersum under the experimental conditions used.
Limitations and considerations
Specific sample sizes, statistical values, and detailed HRV metric definitions are provided in the manuscript and supporting information. The present summary does not invent numerical results beyond those explicitly reported in the source. The authors acknowledge that shell carrying and morphological variation could influence energetics and cardiovascular function, but in this dataset such effects were not detected.
Cardiac function in Cornu aspersum is strongly dependent on behaviorally induced state: retraction is associated with lower heart rate and greater cardiac irregularity, while locomotion is accompanied by increased heart rate and more regular mechanical cardiac oscillations. These findings indicate that even relatively slow-moving terrestrial gastropods show state-dependent cardiovascular adjustments consistent with increased metabolic demand and neural regulation during movement. The laser optocardiography method demonstrated here offers a practical means to study invertebrate cardiac mechanics through intact shells.
The authors state that all relevant data are within the manuscript and its supporting information files. Funding came from personal funds and a university grant (Big Grant IV-FGD003, Dirección de Investigación e Innovación, Universidad del Rosario). The authors declared no competing interests. Experimental details, ethical considerations for euthanasia, and full analytical methods are reported in the published article and supporting materials.