Her brethren are playing in the waters of the deep all over the world, from surface waters to our deepest seas — and they are old. They are some of the oldest animals in the fossil record.
Jellyfish, or sea jellies, are the informal common names given to the medusa-phase or adult phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria — closely related to anemones and corals.
While the name is embedded, Jellyfish are not fish at all. They evolved millions of years before true fish. The oldest conulariid scyphozoans appeared between 635 and 577 million years ago in the Neoproterozoic of the Lantian Formation, a 150-meter-thick sequence of rocks deposited in southern China.
Others are found in the youngest Ediacaran rocks of the Tamengo Formation of Brazil, c. 505 mya, through to the Triassic. Cubozoans and hydrozoans appeared in the Cambrian of the Marjum Formation in Utah, USA, c. 540 million years ago.
I have seen all sorts of their brethren growing up on the west coast of Canada. I have seen them in tide pools, washed up on the beach and swam amongst thousands of Moon Jellyfish while scuba diving in the Salish Sea. Their movement in the water is marvelous.
In the Kwak̓wala language of the Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, jellyfish are known as ǥaǥisama—enjoyed as a tasty snack or used as bait to entice larger marine animals.
The watercolour ǥaǥisama you see here in dreamy pink and white is but one colour variation. They come in blue, purple, orange, yellow and clear — and are often luminescent. They produce light by the oxidation of a substrate molecule, luciferin, in a reaction catalyzed by a protein, luciferase.