Technique · Fields
Jellyfish drift
Half-disc jellyfish with speckled bells and swaying tentacles over a current of flowing blue strokes.
Jellyfish drift is a field drawn for every pixel by the graphics chip. Every piece on Synapse Drip is made from a recipe that layers techniques like this one, and you can change any of it in the Studio.
Good to know
- A group of jellyfish is called a bloom or a smack; blooms can swell to millions when warm water, food and few predators coincide.
- The stinging cells on a jellyfish's tentacles, nematocysts, fire a coiled, barbed thread in a fraction of a millisecond, among the fastest cell movements known.
- The small jellyfish Turritopsis dohrnii can turn back into its juvenile polyp form after reaching maturity, and is sometimes called immortal.
- Public aquariums keep jellyfish in kreisel tanks, a round tank with a slow circular current, so that they are carried gently around instead of pressed against the walls; the design dates from the 1960s.
- A jellyfish has no brain, heart or bones: a ring of nerves around the edge of the bell sets the rhythm of its pulse, and its body is about 95 percent water.
- Jellyfish fossils date from around 500 million years ago, which makes them among the oldest animals with a body made of several tissues.
The mathematics
- A tentacle sways as a travelling wave, x = A sin(k y - w t): the crest slides down the tentacle at the speed w / k, about 0.94 bell radii per second here.
- The bells pulse as 1 + 0.1 sin(1.4 t), a cycle every 4.49 seconds, and widen as they flatten so that the area stays about the same.
- The strokes of the current are lines of equal x after the coordinate has been displaced by slow noise; because no two lines can share a value, they bend around each other and never cross.
- Each jelly is drawn in the order of its row, top to bottom, so nearer ones lie over farther ones without any depth buffer: a painter's algorithm.
In art
- Ernst Haeckel drew jellyfish, among them the Discomedusae, for his Kunstformen der Natur (1899 to 1904).
- Reducing a jellyfish to a half disc and a fringe of lines works because the eye needs only the silhouette to read the animal.
More ways to use it
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