Although the ocean covers 70 percent of our planet’s surface, to date we’ve only explored about 5 percent of it. But we’ve found some pretty amazing stuff in that small oceanic portion: faceless fish, dolphins getting high, massive volcanoes.
Now comes another oddity: a really, really, really old worm.
Scientists have determined that a recently discovered species of deep-sea tubeworm — Escarpia laminata — is likely one of earth’s longest-living animals, with some individual specimens clocking in at more than 300 years old. Studying these tubeworms, the researchers say, could help our understanding of deep-sea evolution. It may also offer insight into why some species seem to outlast everyone else.
E. laminata was discovered only about 30 years ago, and lives in the depths of the Gulf of Mexico thousands of meters below the surface of the water. It’s a species of tubeworm that lives in a cold-seep community, a place on the ocean floor where hydrocarbon fluids come up in the form of methane or hydrogen sulfide gas.
These deep ocean cold-seeps are pretty inhospitable places — but not for the tubeworm. Cold-seep tubeworms don’t have a digestive system at all, so they’re not worried about the lack of available prey. They survive thanks to a symbiotic relationship with a species of bacteria that lives inside them and converts gases into energy. The worms also grow down into the ocean floor, spreading out “roots” that draw up more nutrients from below the sand.
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It’s been known that these creatures can live for a long time. Previous studies have found that other cold-seep tubeworm species, such asLamellibrachia luymesi, can live for more than 200 years. But L. luymesi lives in shallower waters, and the researchers, led by Alanna Durkin of Temple University, wanted to see how long the deeper tubeworms could live. The team’s work, published this month in The Science of Nature, determined that E. laminata might be the oldest species of tubeworm yet — some specimens had been alive for more than 250 years.
“Given the uncertainty associated with estimating the ages of the longest individuals,” Durkin said in a press statement, “there may be large Escarpia laminata tubeworms alive in nature that live even longer.”
The scientists determined the age of 356 tubeworms using a modeling method based on the length of the tubeworms and how much they grew in one year. They also estimated birth and death rates of the species.
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One of their most interesting findings is that the death rate of E. laminata is extraordinarily low: only 0.67 percent of each population dies yearly. This is likely because the tubeworms have few threats below the water, so they can continue to reproduce into old age. Previous studies have also found that organisms at great depth experience slower metabolisms, which may help promote a longer lifespan.
While a 300-year-old tubeworm sounds impressive, it wouldn’t be the longest living organism on Earth, or even in the sea. A specimen ofArtica islandica, a bivalve mollusk that is also known as the ocean quahog, has been estimated to have lived more than 500 years. And plants can of course live much longer. Giant sequoia trees, redwood trees, and some varieties of pine trees can live thousands of years. Compared to them, tubeworms (and us humans), live and die in the blink of an eye.
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