Overview
The String Jellyfish (Apolemia uvaria), often called the barbed wire siphonophore, is a monumental pelagic siphonophore that drifts through the world’s oceans. Rather than a solitary animal, this astonishing marine wonder is a colonial superorganism comprised of thousands of specialized, genetically identical zooids functioning seamlessly as a single integrated entity that can stretch up to nearly 100 feet through open water.
Biology and Physical Characteristics
Apolemia uvaria consists of a central, flexible stem lined with differentiated zooids organized into repeating segments (cormidia). At its apex, a gas-filled pneumatophore regulates colonial buoyancy, followed by powerful swimming bells (nectophores) that pulse rhythmically to drive the superorganism forward. Along the stem, feeding zooids (gastrozooids) digest prey, reproductive zooids (gonozooids) produce gametes, and defensive bracts shield the colony while trailing thousands of stinging tentilla armed with potent nematocysts.
Behavior and Ecology
Drifting passively along ocean currents, Apolemia uvaria deploys its extensive curtain of stinging tentacles into a lethal underwater web to ensnare passing crustaceans, squid larvae, and juvenile fish. The venomous nematocysts instantaneously paralyze prey, which is swiftly contracted by muscular tentacular cords toward gastrozooids for communal extracellular digestion. When disturbed by large predators, the colony pulses its swimming bells and exhibits dazzling blue-green bioluminescence to startle attackers.
Conservation and Human Impact
Evaluated as Least Concern, Apolemia uvaria maintains abundant oceanic distributions worldwide. As an apex gelatinous consumer in pelagic food webs, it regulates planktonic crustacean densities while serving as a crucial nutrient resource for open-ocean sunfish and leatherback sea turtles.
Interesting Factoid
Despite measuring up to 100 feet in length, a string jellyfish is not a single individual, but a cooperative colony of thousands of specialized multicellular beings, none of which can survive independently.
Last updated: October 2026