Zebra Danio Study Shows How Fish Evolved Limbs

Due to a recent study with the Zebra Danio, scientists are one step closer to figuring out how fish evolved limbs and took their first steps on land.

Zebra Danios are a popular freshwater aquarium fish because of their:

• abundant energy
• general hardiness
• inexpensive price tag

Developmental biologists (biologists who study the process of how organisms develop and grow) also use Zebra Danios (biologists tend to call them zebrafish) as an organism to study in the laboratory.

One study, published in a Journal named Developmental Cell, shows how fish may have evolved limbs.

The experiment ran like this–scientists injected extra copies of a gene named hoxd13 into the Zebra Danios (zebrafish). This gene is responsible for making a protein thought to control the development of precursor hands and feet. The gene occurs naturally in Zebrafish, but the associated protein (for growing hands and feet) is only in very low quantities when compared with four-legged land animals or birds.

What the study found is that the fish injected with extra copies of this hoxd13 gene began to develop the precursors to hands and feet, instead of fins.

Based on the results from this study, some scientists believe that the first animals to have walked on land (called tetrapods) may have evolved as a result of the increased expression of this gene.

So…I know this is a saltwater aquarium blog–and not a freshwater aquarium blog…and I know that this is a pretty geeky, evolutionary biology study, but I found it to be pretty interesting. I hope you found it interesting too.

Did you know that zebrafish can regrow their fins, skin, and heart? Maybe I should set up a freshwater aquarium.

You can read a summary of the Zebra Danio study that shows how fish may have evolved limbs here.

Written by Albert B. Ulrich III. Follow me on Google + and Twitter