Otolithology -- what is it?

Well, it's a word I made up to name the science of otolith study.  The real question is...

What are otoliths?

Otoliths, or earstones, are biogenic, calcareous concretions that serve as part of the hearing and balance (acoustico-lateralis) system in fishes.  They consist of CaCO3 (usually in the form of aragonite) precipitated on a protein matrix, and reside in the semi-circular canals under the braincase.  Otoliths increment on a daily basis, and these daily increments are visible in the early stages of a fish's life.  This is the otolith of a striped bass larva.  In reality, it is less than 0.5 millimeter wide.  The rings you see are daily growth increments.

Otoliths are often called the "Rosetta Stones" or "CD-ROMs" of fish biology, because there is so much information stored in them.   Fisheries scientists are now able to obtain a wealth of information on age, growth, environment, and population characteristics of many species of fish.

Some links of interest:

     A good introduction to Otolithology
     A good online manual on Dave Secor’s website

     Another good online manual from J. Jenke, Western Australia
     The otolith page

      A guide to otoliths from the Gulf of Mexico and Atlantic Ocean

      A Norwegian otolith website
     Shape analysis of otoliths


If you have an interesting otolith related website, send me the link, and I will post it here.

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