Fossil Record Reveals Jellyfish More than 500 Million Years Old
Pushes occurrence of jellyfish back some 200 million years
Scientists have described the oldest definitive jellyfish ever found, using recently discovered "fossil snapshots" found in rocks more than 500 million years old.
The jellyfish are unique because they push the known occurrence of jellyfish back from 300 million to 505 million years.
The research will be published on October 31 in the journal PLoS ONE.
"This study clearly shows what paleontologists have long suspected--that jellyfish have a history that's much older than their known fossil record," said Patrick Herendeen, program director in the National Science Foundation (NSF)'s division of environmental biology, which funded the research through the Assembing the Tree of Life (AToL) program, along with NSF's division of earth sciences. "Adding some 200 million years to the age of jellyfish is quite a jump. What's even more surprising is the apparent diversity of jellyfish forms present at that time."
The researchers describe fossils preserving traits that allow them to be related to modern orders and families of jellyfish.
The jellyfish left behind a film in fine sediment that resembles a picture of the animal. Most jellyfish do not leave such a clear impression behind because they are often preserved in coarse sand.
"The fossil record is full of circular shaped blobs, some of which are jellyfish," said Paulyn Cartwright, an ecologist and evolutionary biologist at the University of Kansas (KU), one of the paper's authors. "That's one of the reasons the fossils we describe are so interesting, because you can see a distinct bell-shape, tentacles, and muscle scars."
Cartwright, Bruce Lieberman, a geologist at KU and senior curator of invertebrate paleontology at the KU Natural History Museum, and Jonathan Hendricks, a geologist at KU, collaborated on the research, along with scientists from several other institutions.
Lieberman said the jellyfish the group describes, found in Utah, offer insights into the puzzle of rapid species diversification and development that occurred during the Cambrian radiation, a time when most animal groups appear in the fossil record, beginning roughly 540 million years ago.
The fossil record has revealed much less about the origin and early evolution of soft-bodied animals such as jellyfish than it does about animals with hard shells or bones.
"The fossil record is 'biased' against soft-bodied life forms such as jellyfish, because they leave little behind when they die," Lieberman said. "That means we are still working to solve the evolutionary development of many soft-bodied animals."
With the discovery of jellyfish in the Cambrian, however, the researchers said that there is enough detail to assert that the types are related to the modern orders and families of jellyfish. The specimens show the same complexity. That means that either the complexity of modern jellyfish developed rapidly roughly 500 million years ago, or that the group is even older and existed long before then.
Other researchers involved in the discoveries were Susan Halgedahl and Richard Jarrard, both of the University of Utah, Salt Lake City, Utah; Antonio Marques, University of San Paulo, San Paulo, Brazil; and Allen Collins, Smithsonian Institution, Washington, D.C.
Jellyfish Facts by the Numbers
- 1/3 of the total weight of all life in Monterey Bay is from gelatinous animals.
- 1 microsecond is the time it takes a jellyfish stinger to hit its target. The discharge of the jellyfish’s stinger is among the fastest movements in nature.
- 3 minutes after a person is stung by Chironex fleckeri--a species of box jellyfish that is the most venomous animal in the world—she/he may be dead.
- 8 years after fast-reproducing comb jellies invaded the Black Sea, they dominated it. By 1990, the total biomass of the Black Sea’s comb jellies, which had been introduced into the Black Sea in 1982, totaled about
900 million tons—more than ten times the weight of the total annual fish catch from all of the world’s oceans.
- 20 to 40 people are killed annually from box jellyfish stings in the Philippines alone. On average, one person is killed annually by box jellyfish in Australia.
- 100-foot-long tentacles dangle from large lion’s mane jellies. A 100-foot tentacle is long enough to extend from the bottom to the top of a 10-story building.
- 130 feet is the approximate length of some Siphonophores--long, linear jellyfish-like animals that live in the open ocean. By comparison, the maximum length of the Blue Whale, the largest mammal on Earth, is about 110 feet.
- 400+ vast marine Dead Zones, which are each too polluted for almost all life except jellyfish, currently cover a total area of almost 100,000 square miles around the world. The number of global Dead Zones has doubled about every 10 years since the 1960s. During the summer of 2008, the Gulf of Mexico’s Dead Zone covered about 8,000 square miles, about the size of Massachusetts.
- 1,000+ fist-sized comb jellies filled each cubic meter of water in Black Sea jelly blooms.
- 6,000 oil and gas rigs along with various types of debris--including a submerged aircraft carrier, a discarded bridge and acres of shopping carts--are currently planted on the floor of the Gulf of Mexico. Scientists suspect that these structures create habitat for young jellyfish (polyps) that cling to hard surfaces.
- 38,600 square miles of the North Atlantic (called the New York Bight) have been periodically covered by blooms of salps, a jellyfish-like creature. Scientists believe that these blooms are natural phenomenon that are not caused by human activities.
- 45,000 eggs may be released daily by a single sea nettle in the Chesapeake Bay. A single Mnemiopsis (a common species of comb jelly) may release 8,000 eggs daily.
- 150 million people are annually exposed to jellyfish around the world. About 500,000 people are annually stung by jellyfish in the Chesapeake Bay. About 200,000 people are annually stung by jellyfish in Florida. About 10,000 people are annually stung in Australia by the dreaded Portuguese man-of-war; many other species of gelatinous creatures also cause large numbers of stings in Australia.
- $350 million in losses to the Black Sea’s fishing and tourism industries resulted from the invasion of the comb jelly into the Black Sea. Losses from the ongoing comb jelly invasion of the Caspian Sea are expected to exceed those from the Black Sea invasion.
- 500 million Nomurai jellyfish–which may each weigh up to 450 pounds and sport a bell up to seven feet in diameter--floated into the Sea of Japan daily during recent summer Nomurai blooms. Resulting losses to fishermen in just one Japanese prefecture have, thus far, totaled at least $20 million. (Problem Nomurai have been reported in at least 17 Japanese prefectures.)
- 500 million years+ is the approximate amount of time that gelatinous animals have lived on Earth.