DONALD WLODKOWIC LAB

THERMOTACTIC DECISION-MAKING IN SIMPLE ORGANISMS

Temperature is one of the most fundamental environmental cues shaping the ecology and behaviour of ectothermic organisms. The ability to sense thermal gradients, integrate that information, and execute directed movement toward preferred temperature zones — thermotaxis — requires conserved sensory receptor pathways, neuronal signal processing, and motor decision-making. In organisms with simple or absent nervous systems, thermotaxis thus represents a tractable and ecologically relevant window into basal proto-cognitive capacity.

Our lab has developed a purpose-built miniaturised thermoelectric systems that enables high-throughput, quantitative analysis of thermal preference behaviours across diverse aquatic species. Using this platform, we conducted a systematic multi-species characterisation of thermal preferences spanning nine taxa from freshwater planarians and ostracods through crustaceans, molluscs, and larval zebrafish, establishing species-specific thermal preference profiles and demonstrating that thermotactic decision-making is both robust and quantifiable across a wide evolutionary range. 

Building on this foundation, more recent high-resolution work has characterised thermotactic decision-making in aquatic invertebrates in greater mechanistic depth, demonstrating that thermotaxis in species such as Daphnia involves sophisticated gradient-sensing mediated by conserved TRP ion channel pathways, and that exposure to neuroactive pollutants significantly disrupts these processes — positioning thermotaxis as both a sensitive ecotoxicological endpoint and a direct indicator of proto-cognitive capacity and its vulnerability to environmental perturbation.

Henry, J., Bai, Y., Kreuder, F., Saaristo, M., Kaslin, J., & Wlodkowic, D. (2022). A miniaturized electrothermal array for rapid analysis of temperature preference behaviors in ecology and ecotoxicology. Environmental Pollution 314, 120202. https://doi.org/10.1016/j.envpol.2022.120202 

Han, X., Kumari, S., Do, H., Bevan, C., Wasielewski, O., Hall, M.D., & Wlodkowic, D. (2026). Thermotactic decision-making in aquatic invertebrates: high-resolution behavioral analysis of ecotoxicological effects. Environmental Science & Technology. https://doi.org/10.1021/acs.est.5c16058 

ONTOGENY OF BEHAVIORAL INDIVIDUALITY AND PLASTICITY

How do individual differences in behavior develop over an organism's lifetime? 

We investigate whether and how behavioral individuality (personality) and temporal plasticity emerge and change during ontogeny in simple aquatic organisms.

Our recent research has revealed that both behavioral individuality and plasticity increase as brine shrimp (Artemia franciscana) develop from nauplii to adults, with notable sex differences: males exhibit greater increases in temporal behavioral plasticity compared to females.

 These findings emphasize the importance of considering ontogenetic dynamics to understand how variation in behavior arises and varies over time and between sexes.

Recent publication: 

Favero, M., Do, H., Palomba, M., et al. (2026). Sex differences in development of behavioral individuality and plasticity in brine shrimp. Behavioral Ecology and Sociobiology 80:32. https://doi.org/10.1007/s00265-026-03715-7 

PHOTOTACTIC BEHAVIOURS AND SENSORY DECISION-MAKING

The ability to detect, orient toward, and actively search for light sources represents one of the earliest and most conserved forms of sensory decision-making in the animal kingdom. Phototaxis — directional movement in response to light gradients — is present across an extraordinarily broad range of invertebrate taxa reflecting deep evolutionary roots in the capacity to integrate environmental information and produce directed behavioural responses.

Our foundational work characterising spontaneous behavioural repertoires in brine shrimp (Artemia franciscana) established that early larval stages exhibit strong, quantifiable innate behaviours — including wall preference (thigmotaxis), positive phototaxis, and depth preference — and that these are not fixed reflexes but interact in a hierarchical fashion: phototactic drive consistently overrides edge preference when a light stimulus is present, revealing a capacity for competing stimulus integration and behavioural prioritisation. 

Building on this foundation, we have developed purpose-built high-throughput analytical platforms with programmable photic stimulus systems. A particularly compelling finding has been the phenomenon of light searching behaviour (LSB) — the active, persistent seeking of an extinguished light source in nauplii. LSBs imply a capacity for short-term sensory memory and goal-directed exploration that extends well beyond simple stimulus-response reflexes. We have also shown that sub-lethal exposures to the organophosphate chlorpyrifos and the neonicotinoid imidacloprid selectively disrupt light searching behaviours demonstrating that phototactic sensory-motor circuits are specifically vulnerable to neuroactive pollutants.

Current investigations are extending into behavioral plasticity paradigms across developmental stages, spatial navigation tasks, and maze-based assays, with the aim of characterising how photic decision-making develops and how plasticity in these proto-cognitive traits is established and maintained through ontogeny.

Henry, J., Bai, Y., Williams, D., Logozzo, A., Ford, A., & Wlodkowic, D. (2022). Impact of test chamber design on spontaneous behavioral responses of model crustacean zooplankton Artemia franciscana. Lab Animal https://doi.org/10.1038/s41684-021-00908-7 

Bai, Y., Henry, J., Karpiński, T.M., & Wlodkowic, D. (2022). High-throughput phototactic ecotoxicity biotests with nauplii of Artemia franciscana. Toxics 10, 508. https://doi.org/10.3390/toxics10090508 

USING POLLUTANTS AS EXPERIMENTAL PROBES

The ability to detect, evaluate, and respond to chemical gradients in the environment represents one of the most ancient and fundamental forms of proto-cognitive decision-making. Chemosensory avoidance — the capacity to sense an unfavourable chemical stimulus and execute a directed behavioural response — requires sensory integration, threshold detection, and motor decision-making, and is present across a remarkably broad range of invertebrate taxa.

Chemosensory behaviours in small aquatic invertebrates can be thus as a window into basal decision-making processes, and we have developed purpose-built millifluidic perfusion platforms that enable high-throughput, quantitative chemobehavioural analysis. 

Using native Australian marine amphipods (Allorchestes compressa), we demonstrated that these crustaceans exhibit rapid and robust avoidance responses to environmental stressors including heavy metals and organophosphate compounds — responses detectable well below concentrations that affect survival. 

Notably, exposure to the organophosphate chlorpyrifos produced concentration-dependent shifts in avoidance behaviour — including anomalous attraction at low concentrations — highlighting how subtle disruption of chemosensory processing can fundamentally alter behavioural decision outcomes.

Bai, Y., Henry, J., & Wlodkowic, D. (2020). Chemosensory avoidance behaviors of marine amphipods Allorchestes compressa revealed using a millifluidic perfusion technology. Biomicrofluidics 14, 014110. https://doi.org/10.1063/1.5131187 

MEMORY & LEARNING IN SIMPLE LIFEFORMS

A hallmark of lifeforms is their remarkable ability to express preferences and acquire knowledge from experiences, enabling learning and adaptation to new environments.

Paradoxically, our understanding of basal cognition and levels of biological intelligence in animals with primitive nervous systems remains the most sparse, highlighting a significant gap in our knowledge. Our research endeavors to shed light on memory and learning processes in simple organisms, including planarian flatworms, insects, and larval stages of fish and amphibians.

Unraveling the capacity of simple nervous systems, with limited biocomputational abilities, to facilitate memory formation is pivotal for advancing new frontiers in experimental zoology, comparative animal psychology and diverse intelligence research.

MEMORIES OUTSIDE OF THE BRAIN

Can memories transcend the confines of the brain, relocating within the body, only to reintegrate during brain regeneration? Can memory be inherited across generations or transplanted to different bodies? While these questions may seem like plotlines from a science fiction novel, reports suggest that some trained memories exhibit resilience even amidst brain amputation, as seen in planarian flatworms.

Our research endeavors to delve into this intriguing phenomenon of potential somatic storage of memory engrams and their subsequent imprinting on the regenerating brain. By exploring these uncharted territories, our work has the potential to unlock new avenues for the application of memory-enhancing chemicals in the context of memory resilience and brain regeneration.