Redwood of the reef is longest-lived animal

A new study estimates that one species of sponge can live to be 2,300 years old — that’s about the same as the oldest known redwood tree and about six times the lifespan of the second-oldest animal.

The giant barrel sponge (Xestospongia muta) is the species soaking up the glory of its new title, oldest animal on Earth. Researchers at the University of North Carolina-Wilmington studied giant barrel sponges in the Florida Keys for four-and-a-half years and published their results in the June 20 issue of the journal Marine Biology. Science magazine had a small news item about it in its July 4 issue.

They measured sponge growth both by tape measure and by taking digital photos of the sponges with metric rulers in front of them. By calculating the growth rate of this type of sponge, the team was able to estimate the ages of sponges by analyzing their sizes in photographs.

The oldest giant barrel sponge measured in the study was estimated to be 127 years old. The team also estimated, from a photograph, that a giant barrel sponge discovered off of the Caribbean island of Curacao in 1997 was about 2,300 years old. The study’s abstract noted that “Although age extrapolations for very large sponges are subject to more error, the largest sponges on Caribbean reefs may be in excess of 2,300 years, placing x. muta among the longest-lived animals on earth.”

So the record age is an estimate and the record-setting sponge died in 2000. Still, it’s interesting to contemplate these creatures that live so long. The next oldest individual animal is the ocean quahog, a clam that lived to 374 years. The oldest redwood tree is about 2,000 years old. The oldest living thing ever found — estimated to be 600,000 years old — was a type of bacteria discovered in ice cores in Canada, Siberia and Antarctica. If you’re curious, Wikipedia has a list of the longest-lived organisms.

I’m not a SCUBA diver so I haven’t seen these giant barrel sponges up close. Have you? What do you think of them and their claim to the title of oldest animal?

July 9, 2008

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Dan Kulpinski

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