Oceaankardes

Oceaankardes are a fictional group of pelagic marine organisms described in speculative biology and science fiction. The term combines oceaan, the Dutch word for ocean, with kardes, meaning sisters, to evoke paired, connected individuals that appear in oceanic blooms.

They are gelatinous and mostly transparent, with an umbrella-shaped bell and a crown of long tentacles radiating from the rim. Bioluminescent cells line the bell and tentacles, capable of coordinated flashes to communicate and deter predators. Individuals range from a few decimeters to over a meter in size.

Oceaankardes inhabit midwater to bathypelagic zones across temperate and polar regions, typically at depths where light is scarce. They form loose aggregations during feeding and breeding, and are often observed near nutrient-rich currents.

Their diet is composed of plankton and small nekton captured by the tentacles. Bioluminescence is used to coordinate movement within groups and to confuse predators during escape. Reproduction is described in speculative accounts as external fertilization with gametes released into seawater; some sources suggest seasonal spawning.

The concept originated in speculative field reports and world-building texts from the early 22nd century and has since appeared in various works as a symbol of ocean connectivity and the aesthetic of bioluminescence.