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.
