19 July 2017

Invertebrate life expectancy record

A long-lived worm was found at the bottom of the Gulf of Mexico

Elizaveta Ivtushok, N+1

American scientists have studied the life cycle of a population of tube worms of the Escarpia laminata species and found out that they are one of the longest-lived creatures on Earth. By tracing changes in the length of the tube worm's body and simulating its growth over time, the researchers found that representatives of this species can live up to 250 years. Article by Durkin et al. Extreme longevity in a deep-sea vestimentiferan tubeworm and its implications for the evolution of life history strategies is published in the journal The Science of Nature.

The depths of the ocean are the habitat of many long-lived organisms due to the low probability of death from predator attacks and the presence of cold seeps — areas in the seabed through which substances enter the water that provide a favorable environment for autotrophs to live. The sustenance of tube worms depends on the autotrophic microbes living inside them, which oxidize methane and hydrogen sulfide (substances of volcanic origin entering the water due to cold seeps) necessary for their life. The stability of life in symbiosis with bacteria and the low temperature of the sea depths are reliable sources of longevity, therefore, tube worms, in particular representatives of species Lamellibrachia luymesi and Seepiophila jonesi, can live up to two hundred years.

The authors of the new work investigated a little—studied species of tube worms living in the depths of the ocean - Escarpia laminata. Representatives of this species live at a depth of 1000 to 3300 meters at the bottom of the Gulf of Mexico. To this type of tube worms, scientists applied the same method of studying annual growth that was used to study tube worms of the species L. luymesi.

On the right are worms labeled with dye to study annual growth

356 representatives of the E. laminata species were measured in situ, labeled with a waterproof acid dye of blue color and collected a year later. The unpainted area that appeared during this time on the worm's body was an indicator of the annual growth of each individual representative.

Distribution graph of annual growth of E. laminata (cm/year, on the Y axis)
depending on the initial length (cm, on the X axis)

Having received annual growth data of the tubular worm, the researchers conducted a simulation of the growth of E. laminata. The simulation method was based on studies of another tube worm, L. luymesi. Scientists measured the average age of both an individual representative of each population and the average age within a single population. 

It turned out that the average age of one tube worm with a length of 50 centimeters is 116.1 years (for comparison, with the same length, the age of representatives of L. luymesi and S. jonesi is estimated at 21 years and 96 years, respectively). The longest (and, accordingly, the longest-lived) of the collected representatives of E. laminata turned out to be more than 250 years old.

Scientists suggest that the reason for the longevity of tube worms is a decrease in the metabolic rate, which became possible due to an increase in the depth of the species' habitat.

With a life age of more than 250 years, the E. laminata tube worm is second only to one known long—lived invertebrate, the Artica islandica mollusk, whose age may exceed 500 years. You can read about the vertebrate centenarian, the Greenland polar shark, in our article.

Portal "Eternal youth" http://vechnayamolodost.ru  19.07.2017

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