Siphonophores are free-living predatory colonial hydrozoan cnidarians found in every ocean of the world. Siphonophore tentilla (tentacle side branches) are unique biological structures for prey capture, composed of a complex arrangement of cnidocytes (stinging cells) bearing different types of nematocysts (stinging capsules) and auxiliary structures. Tentilla present an extensive morphological and functional diversity across species. Tentilla have a precisely coordinated high-speed strike mechanism of synchronous unwinding and nematocysts discharge. Here we characterize the kinematic diversity of this prey capture reaction using high-speed video and find relationships with morphological characters.

Offshore live siphonophore tentilla and nematocyst discharge videos. Phantom Miro 320S High-Speed camera C-mounted on a stereoscopic microscope. Kinematic measurements taken from the original .cine files using PCC software and a static photograph of a ruler at the same magnification for scale. Cine files can be reconstituted from the mp4 and chd files.

Install Phantom PCC software on a Windows PC. Batch convert MP4+chd files to CINE files. Open the scalebar image to set scale. Open the .cine file to measure accelerations, distances, and speeds.