Look in a Microscope to Determine the Age of a Shrimp, Crab, or Lobster!

Abstract

The ability to determine the age of commercially important aquatic species is important to managing their populations. Whereas the age of most aquatic animals can be found by counting annual growth bands in hard structures, such as the fish otoliths (stone-like structures in the ear that are important for balance and orientation) and bivalves' shells, a technique to directly and accurately age individual crustaceans does not exist. At least it didn't until the recent study by Raouf Kilada, Bernard Sainte-Marie, Rémy Rochette, Neill Davis, Caroline Vanier, and Steven Campana. This is a bit of surprise because nothing equivalent to the hard structures of fish or bivalves had been found, or even expected to exist, in crustaceans. This is simply because this group of animals grow by molting or by shedding off their skins. Not only does molting frequency vary considerably among species of crustaceans, but molting individuals are assumed to lose and replace all calcified structures, including the cuticle (exoskeleton), that might record annual growth.