TRIPOD FISH

      Up to 16,000 feet down, on the totally dark bottoms of the Atlantic, Pacific and Indian Oceans, lives strange-looking, foot-long, adult fish called tripod fish.  As young fish, tripod fish swim in the open oceans in search of shrimp, krill, small crustaceans and tiny fish.  These youngsters have huge fins that make them look larger than they are to discourage would-be predators.

     But as those immature tripod fish mature, their two pelvic fins and the lower part of their tails become up to three feet long.  Meanwhile, they slowly sink to the desert-like ocean floors where they live out the rest of their solitary lives using those elongated, rigid fins, like stilts, to stand still a couple of feet above ocean floors and wait for sustenance to drift by in the slight currents.  

     Each tripod fish pushes its long fins into the ocean floors to help anchor themselves while they wait for food.  Tripod fishes' habit of standing still while waiting to ambush food helps conserve energy in a habitat where food is scarce.  Those long fins, that act like stilts, can only work on ocean bottoms.  And, miraculously, that is where they developed.  

     A few tripod ancestors developed long fins over time, which allowed those fish to be more  successful in getting food above ocean floors than their relatives that didn't grow long fins.  Because those long fins benefitted fish bearing them, long-finned fish replaced their relatives that long ago died of starvation because they didn't grow long fins.  Now all tripod fish have long, stilt-like fins.      

     Tripod fish have small eyes and are blind, due to living in total darkness at the bottom of oceans.  They have silvery scales, and large mouths, to scoop up prey creatures, including small shrimp, krill, fish and other critters they can swallow.  The pectoral (front) fins of these mature fish are modified like antennae, to sense movement in the water that could mean prey.  And those front fins guide food toward the large mouth. 

     Each tripod fish has male and female reproductive parts.  If they find each other in the dark vastness of the ocean floors, they will breed.  But if they can not find a partner for reproduction, each fish can fertilize its own eggs with its own sperm, an adaptation to reproducing in the immensity of the oceans. 

     Every niche on Earth is filled with at least one living being.  Tripod fish are a good example of that.  What are the chances of a fish developing the right adaptation in the right habitat, including really long fins to stand motionless on ocean floors to catch prey creatures?  Probably there have been millions of attempts by millions of life forms to adapt to the many niches on Earth through the history of this planet.  But most of them were unsuccessful because they were wrong attempts that didn't benefit the species that produced them.  We only know the successful ones in any one niche, including stilts on ocean floors.  

     Life on Earth is forever evolving, forever changing in changing environments.  Species that don't change, or evolve in ways that don't benefit them, will soon become extinct.    

 

               

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