Fish Out of Water 233In 2014, scientists published a remarkable study (Standen et al. 2014). They took popu-
lations of the African ray-finned fish known as the bichir, or Polypterus (distantly related to
sturgeons and paddlefish), and made them cross over dry land over and over again. Within
8 months, the bichir that had had been raised on land had modified their ray fins and the
muscles to control them so they were more efficient walkers; those that were kept in their
normal water habitat did not change. The remarkable footage of these walking fish can be
seen online by searching for videos of “walking fish Polypterus.”
None of these fishes are perfectly adapted for land, but are “jury-rigged” to live on land
just long enough to accomplish certain tasks. They must inhabit humid climates and remain
close to water so they don’t dry out, and they return to the water frequently to restore their
water balance. They don’t have lungs but make do with their gills, swim bladders, and the
moisture in the air to breathe for extended periods of time without lungs. They don’t have
FIGURE 10.4. A number of ray-finned fishes have evolved the ability to live on land and crawl around,
or they have modified their rayed fins into walking appendages for use in creeping along the seafloor. (A)
The “walking catfish,” which wriggles along the ground between ponds when its home pond dries up or
becomes too crowded. (B) The mudskipper, which spends most of its life out of water sitting on the mudflats
or mangrove roots. ([A] and [B] from Romer 1959) (C) The frogfish, which has modified its ray fins into
“fingers” that enable it to creep along the bottom. (From Clack 2002: fig. 4.15; used with permission)
(A) (B)
(C)