Thursday, August 30, 2007

How to tell a fishes’ age

Scientist had found a way that can determine the fish age, where they have been and what they eat. It's all available in the earbone. Fish have bones in their heads called otoliths (oto meaning ear and lith meaning stone). These bones is similar like a gyroscope will help the fish keeping its balance in the water.


When a fishes’ grow slows in the winter a darker denser ring forms. In the warmer months when a fish is growing faster and a clearer ring is formed. These yearly growth rings are called annuli, which are similar to the rings found in tree stumps. You can count the rings in the otolith or stump and determine age. When an otolith is removed from a fish, sectioned into thin slices and viewed through a microscope, it reveals a pattern of light and dark concentric rings.

Otoliths can tell us about age and growth patterns, even about the environments in which the fish have lived. As technology improves, scientists are able to get more and more information from these tiny bones.

Source : http://www.gulf-shores-alabama.net/fish-age.html
Source : http://www.reef.crc.org.au/media/otolith.htm

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