Underwater glider

Phronimes - Monstres des tonneaux
Recyclant salpes et méduses, la femelle phronime construit des tonneaux gélatineux et y élève sa progéniture.

Colony of diatoms genus Bacillaria whose single cells slide against each other (Video : Sophie Marro)

Plankton
Plankton are a multitude of living organisms adrift in the currents.Our food, our fuel, and the air we breathe originate in plankton.

Sea Urchin - Planktonic Origins
Barely visible to the naked eye, sea urchin larvae grow and transform into bottom-dwelling urchins.

Embryos and larvae
Drifting in the currents, embryos and larvae perpetuate the species and are food for multitudes.

This video describes how to perform the Ludion experiment and explains the physical processes involved.

Illustration in synthesized images of the seasons of the ocean: a year from the Antarctic - Animation Clement Fontana

Siphonophores - The longest animals on the planet
Cousins of corals, siphonophores are colonies of specialized individuals called zoids. Some catch and digest their prey, others swim, or lay eggs or sperm.