Nematostella Imager

The sea anemone Nematostella vectensis possesses conserved clock genes, displays light-entrained circadian locomotor rhythms, and exhibits sleep-like states linked to DNA repair, making it a key model for circadian regulation and sleep evolution. However, no existing platform integrates the timing precision, illumination control for scheduled experimental design, and automated behavioral analysis required for long-term studies. We developed an open-source hardware–software system built around an ESP32 microcontroller-based imaging unit, providing near-infrared and white-light illumination for entrainment, sub-second timing accuracy, and environmental logging at a total cost of ~600 €. Two companion napari plugins then automate the full workflow — from region-of-interest detection and movement quantification through circadian rhythm analysis to sleep-like state classification. Software Recording plugin — Nematostella-time-series: synchronized timelapse capture, LED control, ESP32 communication. Analysis plugin — napari-hdf5-activity: ROI-based activity extraction and circadian analysis (Chi² periodogram, FFT, Cosinor, phase clustering). Web firmware installer — flash ESP32 firmware from the browser (Chrome/Edge, no toolchain required).

An adult Nematostella vectensis.

Hardware

The assembled imaging chamber: HIK robotics monochrome camera, exchangeable LED lid (IR or white), ESP32 controller and DHT22 temperature sensor.

Recording

Top: snapshot of the 6-well imaging plate with auto-detected ROIs (1–6). Bottom: corresponding activity signals of the four Nematostella vectensis animals across the 12 : 12 light / dark phases. Activity is the mean absolute per-pixel frame-to-frame difference (MinMax-normalized) within each animal's ROI.