This was a scientific animation project to show how nematocysts work.
Nematocysts are stinging cells found in cnidarians, such as jellyfish and sea anemones. It contains a coiled, barbed filament that discharges instantly upon contact, injecting toxins into prey or enemies. The discharge is triggered by contact or chemical stimuli that release Ca+ ions from within the cell. Osmotic pressure forces H2O into the cell, creating a high pressure that drives the filament out at incredible speed. The filament is discharged in three phases, where eversion occurs.
Music by ShadowsAndEchoes
Copepod model by JuanG3D
Process
I started researching how nematocysts work and found a detailed publication (Karabulut et al., 2022) as reference.
I then set out to create a colorful moddboard and storyboard.
The modelling in Blender was rather straight forward as no exact shapes had to be adressed. I used curves and shapekeys to animate the mesh as eversion.
For the Ca+ ions, I used a particle system with an emission material and fog glow in the compositor. The flooding of the H2O was done by creating, modifying and animating curves in geometry nodes and in the material. See full work breakdown here.
References
Karabulut, A., McClain, M., Rubinstein, B. et al. The architecture and operating mechanism of a cnidarian stinging organelle. Nat Commun 13, 3494 (2022). https://doi.org/10.1038/s41467-022-31090-0
Created 2026