This is a picture of some Siromese on their home planet Hydrosia. They are a species of jellyfish that produce a pheromone to lure their food. A Siromis will make dance-like movements to release this into the water while catching any fish that get close enough. Siromese are popular with local tourists for these "dances" they perform.

You can find more Siromis info here: https://www.weasyl.com/~oddymcstrange/submissions/1797493/alien-species-summary-siromis