Algae ID

Videos

Motion is one of the best clues for identifying a dinoflagellate. These are my microscope videos.

They are all on my YouTube channel (YorickSanchez). The magnification is the objective times the 10X eyepiece, plus any camera zoom.

Ostreopsis

Look for the cells spinning around a fixed point like a tetherball. See the Ostreopsis page.

Ostreopsis sp. at 40X Watch on YouTube
Ostreopsis at 100X Watch on YouTube
Ostreopsis at 400X Watch on YouTube
Ostreopsis sp. at 400X Watch on YouTube

Amphidinium

Look for the cells gliding smoothly along the surface, and for the grooves at the top of the cell. See the Amphidinium page.

Amphidinium sp. at 40X Watch on YouTube
Amphidinium sp. at 100X Watch on YouTube
Amphidinium sp. at 400X Watch on YouTube
Amphidinium sp. at 400X, in focus Watch on YouTube

Predation

Oxyrrhis marina feeding on Amphidinium carterae Watch on YouTube

A practical walkthrough

My videos are mostly raw microscope footage. If you want a polished, step-by-step video about finding and dealing with dinos in a reef tank, this one from Reef Rookies is worth your time. It is another aquarist's guide, not mine, so you may notice differences from my notes on the treatment page.

How to Identify and Fix Dinoflagellates in a Reef Tank! (Reef Rookies, 2026) Watch on YouTube

From other aquarists

Aquarists who sent me their microscope videos have given permission to share some of them. You will find them on the Amphidinium, Prorocentrum, and other dinoflagellates pages.

More

A video of Symbiodinium is on the other dinoflagellates page.