Image of the Day: Internal Restructuring
Image of the Day: Internal Restructuring

Image of the Day: Internal Restructuring

Juvenile eels break down bone tissue and rebuild it in preparation for mating.

May 20, 2019
Chia-Yi Hou

ABOVE: Computed tomography scans of female and male eels in various maturation stages shown in different colors. This process involves a successive loss of bone as they mature.
LARISSA YOKOTA RIZZO AND MARKO FREESE

European eels, Anguilla anguilla, start out yellow in color as juveniles and over the course of their lives transform into a shiny silver color. The eels spawn in the ocean and the larvae travel to coastal water, and when those offspring return to the ocean to spawn themselves, they stop eating, shrink their guts, and undergo internal structural changes, namely, breaking down and rebuilding their skeletons. Researchers induced artificial maturation by administering hormones to juvenile eels to study the breakdown of the skeleton.

M. Freese et al., “Bone resorption and body reorganization during maturation induce maternal transfer of toxic metals in anguillid eels,” PNAS, doi:10.1073/pnas.1817738116, 2019.

The internal structure of a yellow eel vertebra before maturation
PAUL ECKHARD WITTEN
Researchers artificially induced maturation in an eel by giving it hormones and took this image of a vertebra, showing internal structural changes in bone tissue.
PAUL ECKHARD WITTEN