These fishes go through one amazing metamorphosis

Dawn Roje, a grad student at the Museum’s Richard Gilder Graduate School, is currently studying flatfishes in the the Solomon Islands. This is her first dispatch from the field.

Finding treasure during my first two days out at sea is an odd mix of exhilaration and calm. Exhilaration in finally obtaining the specimens I crossed the dateline for and reassuring in that anything else I collect beyond this point is an excess of riches.

Pictured: Halibut (Shane Anderson via Wikimedia Commons)

The animals I am focused on collecting are the larvae and juveniles of what we are used to seeing on our plate at dinner: halibut, flounder, sole, and fluke, the flatfishes.

Before flatfishes make it to the fish market they travel the world’s oceans as plankton, looking and living quite differently than the adults. As larvae they appear to be like all other fishes with an eye on each side of the head, but then something truly amazing happens. Their skull softens, one eye moves over the top of the head and they begin swimming on their side as they settle out of the water to live the rest of their life hiding in plain site of the bottom of the sea.

These fishes go through one amazing metamorphosis

Flounder (Wikipedia/Moondigger)

How and why do they do this, you ask? Well, that is exactly that I am trying to figure out. I, along with the much-needed and appreciated support of my friends and colleagues, have been collecting different species of flatfishes during various stages of development to study their metamorphosis. From our first mid-water trawl in 600 meters of water off the Solomon Islands, I got a beautiful flatfish larva still swimming upright, but with it’s right eye inching its way over to the left side of it’s head. The very next day on a scuba dive I collected another individual, but this one was a juvenile that had just completed its metamorphosis.

Fortuitously, this all happened in the first couple of days. This kind of luck is rare, but glorious. This expedition and these samples make it possible to understand the mechanism of the one of most amazing body plan transformations in biology. Today I am a happy biologist and I can’t wait until tomorrow’s catch.

Read more dispatches from The Explore21 Solomon Islands Expedition here.