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From Fin to Leg – Did a Mutation Help Ancient Fishes Conquer Land?

Australian LungfishHello, Frank Indiviglio here.  If you stare long enough at a Lungfish or Mudskipper (as I have, often causing my co-workers to wonder…), it’s easy to picture a similar creature leaving an ancient sea and setting forth to explore the land in the distant past.  Indeed, evolutionary biologists tell us that a fish very much like today’s Australian Lungfish (Neoceratodus fosteri) did pull off such a feat some 360 million years ago, thereby setting the stage for the rise of the amphibians, reptiles, birds and mammals. 

A Fortuitous “Mistake”?

But how, specifically, did a fin “turn into” a leg?  Researchers at the University of Ottawa believe they have a clue. 

According to an article in a recent issue of the journal Nature, when certain genes are suppressed in Zebrafishes, fin growth is inhibited and, theoretically, limb growth might possibly begin.  Conceivably, a genetic defect could have stunted fin growth in ancient fishes, rendering the fins more useful for “walking” than swimming.

Keeping Lungfishes and “Walking Fishes”

Gambian MudskippersSeveral fishes that might be described as “walkers” are also fascinating aquarium subjects.  I’m especially fond of Mudskippers, Toadfishes, Lizardfishes, Walking Catfishes and, especially, Lungfishes.

Lungfishes can become great pets, with captive longevities approaching 30 years. The species most often available in the pet trade is the West African Lungfish, (Protopterus annectans annectans). These brutes may eventually reach 3 feet in length, so plan accordingly!  They are also escape artists, and are almost always intolerant of tank-mates, even similarly-sized Lungfishes of the opposite sex.  I’ll cover their care in the future…until then, please write in if you decide to keep one, and I’ll send along care information.

The Australian Lungfish mentioned above is an incredible beast, but unfortunately is never available in the trade. I’ve been lucky enough to have observed them at feeding time in an aquarium in Japan – where part of their diet is plantain chunks!

Further Reading

Please see my article on Mudskipper Care for a look at the fish world’s most talented walker (and tree-climber!).

Video of the amazing Australian Lungfish.

Read more about the research described above here.

Please write in with your questions and comments. 


Thanks, until next time,

Frank Indiviglio

Australian Lungfish image referenced from wikipedia and originally posted by Tannin

Gambian Mudskippers image referenced from wikipedia and originally posted by Christian Torrissen

One comment

  1. avatar

    Very cool. There are a lot of fish that like to hang out on rocks and are poor swimmers (hawkfish). However, I will freak out if I see them climb out of the tank and begin walking around!

About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.