Teach Your Fish How To Walk

Flipping Your Fins

Four hundred million years ago, our ancestors crawled out of the sea. Last year, biologist Emily Standen imitated the ancient feat by raising pet store fish on land. A species called the Senegal bichir can breathe moist air through a primitive lung and scramble around on its front fins. After raising juvenile fish out of water for eight months, Standen’s experiment revealed that the bones supporting the bichirs’ fins had changed shape to make walking easier. In our fishy forebears, similar adaptations may have paved the way for genetic changes. Find out for yourself—create a living fossil in your living room.

Materials

• Medium-size acrylic aquarium
• Sand and gravel
• Water
• Airline tubing and control kit
• Bucket
• Hot glue gun
• Aquarium pump and filter
• Safety pin
• Senegal bichir

Instructions

1. Drill a small hole in one wall of the aquarium, about an inch from the bottom. Line the tank with an inch of sand and gravel; add water until there is a layer about 1/16 of an inch thick on the bottom of the tank.

2. For drainage, thread airline tubing through the hole until one end reaches the water inside, and place the other end in a bucket below the aquarium. To secure the tubing and prevent leaks, seal the hole’s edges with hot glue.

3. Fill the bucket with water and clip the filter to the side. Take a T-junction from the kit, connect a valve to the perpendicular part of the T, and hook airline tubes onto both arms.

4. Connect the tube on one arm to the pump, and string the other arm’s tube across the top of the tank. Use a pin to poke holes in the tank’s tubing so water will come out in a fine mist.

5. Drop the T-junction in the bucket. Optionally, add plants to the tank to spruce up the environment. Then introduce the young Senegal bichir to its new home.

This article was originally published in the April 2015 issue of Popular Science, under the title “Teach A Fish To Walk.”