Jellyfish Gone Wild — Text-only | Flash Special Report
Where They Live
THE LONG TENTACLES OF GELATINOUS ANIMALS WRAP AROUND THE GLOBE
JELLYFISH LIVE ALL OVER THE WORLD
Jellyfish and other gelatinous animals live in every ocean, from the Caribbean to the Arctic. They also inhabit every depth of water, from shallow waters to the darkest, deepest abysses. No marine environment is too hostile for jellyfish and other gelatinous animals.
For example, scientists studying the floor of the Pacific Ocean near Costa Rica recently discovered colonies of a bell-shaped, hot-pink jellyfish living on volcanic vents located 8,500 below the ocean’s surface. Emitting iron-darkened water, these scalding, deep-sea vents present one of the harshest environments on Earth.
Jellyfish are also found in a limited number of inland seas and freshwater lakes.
NUMBERS OF SPECIES
The official count of the total number of species of true jellyfish is currently at about 200. But this figure is rapidly increasing and may ultimately reach about 2000. Why? Because scientists are continually identifying new jellyfish species as they:
- Explore more marine environments.
- Use ultra-sensitive DNA analyses to distinguish new species that were indistinguishable by relatively crude comparisons of body shapes and other physical characteristics traditionally used to identify jellyfish species.
WHO LIVES WHERE
Some species of gelatinous animals have narrow geographic ranges; others have broad ranges. Environmental conditions that help determine the geographic ranges of gelatinous animals and the timing of their blooms include the following factors:
- Food: During, the summer availability of prey that are eaten by gelatinous animals tends to increase.
- Water salinity: Water salinity varies from water body to water body. Water salinity may be impacted locally by currents and by changes in the flow of freshwater rivers into coastal areas that are caused by variations in climate and weather and by dams.
Some species of gelatinous animals prefer water with relatively high salinity; others prefer water with relatively low salinity; and others, like the comb jellies that live along the East Coast of the United States and in several European seas, can thrive in low or high salinity waters.
- Currents: Currents can sweep gelatinous animals together into swarms and carry them thousands of miles. For example, currents sometimes carry the Portuguese Man-of-War, which may travel in mobs of 1,000 or more, from Florida as far north as Cape Cod.
In addition, currents may transport gelatinous animals into non-native habitats. If invasive species of gelatinous animals are swept into non-native habitats, where they encounter few or no predators and where their environmental needs are met, they may colonize them. A case in point: The Gulf of Mexico has been colonized by various species of invasive jellyfish--some of which may have been swept there from the Caribbean by currents.
- Temperature: Increases in temperature increase the rates of growth and reproduction of many jellyfish species.
JELLYFISH UNDER THE ICE
A diver extends his fingers towards the tentacles of a jellyfish in Antarctica's McMurdo Sound, where water temperatures are below 30 F.
Credit: Henry Kaiser, National Science Foundation
JELLYFISH ON VOLCANIC VENTS
The pink jellyfish and spiky tubeworm casings that festoon recently discovered volcanic vents near Costa Rica are like "the serpent-haired Medusa of Greek myth," said expedition leader Emily Klein. Credit: Emily M. Klein, Duke University