Growth rings on a lobster can tell its age'

Scientists for the first time have figured out how to determine the age of a lobster — by counting its rings, like a tree.
Nobody knows how old lobsters can live to be. Some people estimate their age extends beyond 100 years.
According to Raouf Kilada, research associate at the University of New Brunswick, knowing — rather than simply guessing — their age and that of other shellfish could help scientists better understand the population and assist regulators of the lucrative industry, the 'CBC News' reported.

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Scientists, until now, deduced a lobster's age judging by size and other variables. But it's now known that lobsters and other crustaceans, such as crabs and shrimp, grow one ring per year in hidden-away internal spots, Kilada said. "Having the age information for any commercial species will definitely improve the stock assessment and ensure sustainability," Kilada said.
Scientists already could tell a fish's age by counting the growth rings found in a bony part of its inner ear, a shark's age from the rings in its vertebrae and a scallop or clam's age from the rings of its shell.
However, crustaceans posed a problem because of the apparent absence of any permanent growth structures. It was thought that when lobsters and other crustaceans molt, they shed all calcified body parts that might record annual growth bands.
Kilada and five other Canadian researchers took a closer look at lobsters, snow crabs, northern shrimp and sculptured shrimp.
They found that growth rings, in fact, could be found in the eye-stalk — a stalk connected to the body with an eyeball on the end — of lobsters, crabs and shrimp.
In lobsters and crabs, the rings were also found in the so-called "gastric mills," parts of the stomach with three teeth-like structures used to grind up food.
To find the growth bands, the scientists dissected the eye-stalks and the gastric mills, cut out sections and viewed them under microscopes.
"We've thought lobsters could live to 100 years old, and this new ageing technique will be a way to document that," said Bob Bayer, executive director of the University of Maine's Lobster Institute.