Daily Devotional – July 17

Biology

Did you know that blind cave fish were designed to go blind! Scientists once thought it was by accident. Cave fish are a generic term for freshwater fish found in - you guessed it, caves. Geneticists have found that blind fish living in caves are almost identical to those in the river outside the cave. The only difference seems to be that the cave fish have smaller eyes, or no eyes, or eyes lighter in color. Actually, for fish living in a dark cave, this is an advantage. A highly developed visual system uses up to 15% more energy and soft eye tissue is easily damaged if bumped into the walls of a cave. Instead, cave fish depend on their sense of smell and sensitivity to water pressure changes. Also, being in a dark cave, eye coloring has no purpose and it takes extra energy to maintain eye color. So if cave fish have eyes, they are lighter in color. Are these changes a mutational degeneration? Actually, cave fish are not regressing, but well designed to live in caves.

Conrad Waddington, a biologist, proposed the idea that many animals have a mechanism allowing environmental changes to switch on genes, when the change would benefit the animal. Such a mechanism is found in blind cave fish - involving a protein called HSP90. When a cave fish embryo experiences subtle factors such as lower electrical conductivity in the water (it is believed that cave water has lower conductivity because the water has less salt), the growing embryo senses these outside conditions and turns off the HSP90 protein. This causes a reduction in fish’s eye size. These eyes have shallow sockets and can even be scaled over. When these same blind cave fish were introduced into water outside the cave, their offspring were born with fully functioning eyes within two generations!

Scientists are discovering that we have “flexible genetics.” This is no surprise to Bible-believing Christians; God has simply pre-programmed creatures with the ability to adapt to different environments.

And his brightness was as the light; he had horns coming out of his hand: and there was the hiding of his power.

~ Habakkuk 3:4

Source: "Pearls in Paradise" by authors Bruce Malone and Jule Von Vett

References for this devotional.