July 17 (UPI) -- Scientists believe a rare tube worm species found in the Gulf of Mexico is the longest-living animal on Earth. According to their latest research, the species, Escarpia laminata, can live for more than 300 years.
Escarpia laminata are known to colonize cold seeps on the floor of the Gulf of Mexico at depths between 3,200 and 10,000 feet. The deep-lying tube worms aren't as well-studied as their shallower peers, Lamellibrachia luymesi and Seepiophila jonesi.
Cold seeps are hydrothermal vents leaching hydrogen sulfide, methane and other hydrocarbon-rich fluids into the cold ocean waters. Though cold seeps are typically colder than other types of hydrothermal vents, the gases bubbling up from underground are often warmer than the surrounding water.
To determine how long Escarpia laminate are, scientists collected several hundred tube worm specimens from the deep-lying cold seeps. Back in the lab, the tube worms were kept under conditions similar to their natural environs and scientists measured their growth rates.
Researchers have previously modeled the longevity of Lamellibrachia luymesi using annual growth rates, rates of death and reproduction among tube worm populations. Similar modeling techniques allowed scientists to estimate the lifespans of the Escarpia laminata specimens.
The scientists found several of the tube worms were older than 250 years old. A few were more than 300 years old. Most of the specimens were between 100 and 200 years old.
"At more than 250 years old, Escarpia laminata achieves a lifespan that exceeds other longevity records," Alanna Durkin, a researcher at Temple University, said in a news release.
Durkin and her colleagues published their analysis of Escarpia laminata's longevity this week in the journal The Science of Nature.
The new study suggests the tube worm species is one of the oldest known animals. The longest-living land vertebrate is the Galapagos giant tortoise. One tortoise was found to be 177 years old. Bowhead whales are the longest-living mammal -- scientists have identified whales as old as 211 years old. Scientists believe the marine clam Arctica islandica can live beyond 500 years.
"Given the uncertainty associated with estimating the ages of the longest individuals, there may be large Escarpia laminata tubeworms alive in nature that live even longer," Durkin said.