Amazing images reveal fishes' hidden anatomy


These images are the work of a scientist at Washington University who bleaches and stains the bodies of fish to expose the skeletal tissue through the skin and flesh.

Professor Adam Summers, is the associate director of Comparative Vertebrate Biomechanics at the at the University of Washington and he uses the method as part of his research into skeletal shape.

The fish are collected either as by-catch from fishery operations, incidental mortality during scientific collection, or as part of a study on the developmental trajectory of the fish skeleton.

The technique uses two dyes: Alcian Blue to stain cartilaginous elements a deep blue and Alizarin Red S to turn mineralised tissue crimson.  

The specimen is then lightly bleached with hydrogen peroxide to remove dark pigments, before the flesh is dissolved with Trypsin — a digestive enzyme found in your intestine, which attacks most proteins but not the collagen that holds the skeleton and skin together. To make the skin and remaining connective tissue invisible the entire specimen is then immersed in glycerin, and the result is that the flesh seems to disappear.

The technique is only suitable for specimens less than 1cm in thickness and processing larger animals can take several months compared to just a few days for a small fish.

These images form part of an exhibition called Cleared which is to go on display at Seattle Aquarium. It includes the lumpsucker (pictured above), skate, rays and sculpin.

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