You do not know what a “riblet” is? It is not an animal. airlines in the United States are saving $300,000 a year because of riblets. Here is the story behind them:

Scientists at NASA tried to figure out how certain water creatures could swim so rapidly. They studied some fast-moving fish for months.

They discovered that the friction of the fish’s body, as it moves through the water, ought to be great enough to slow it quite a bit. Yet the amount of drag that should be present – simply was not there! Given the drag of the water and the amount of fin motion, something was enabling the fish to swim much faster through the water than it ought to be able to swim.

Then the experts figured it out: riblets. These are small triangular-shaped grooves on the outer surface of the skin. Riblets are only found on fast-moving fish; never on fish which have no need to swim rapidly.

These grooves run from front to back. As the water touches the body, it is carried along in these riblets, and this reduces the amount of frictional drag as the creatures swims rapidly through the water.

NASA’s Langely Research Centre developed the riblets and tested them in wind tunnels. They then asked 3M Company to manufacture riblets in large, flat vinyl sheets. When these sheets were placed on the outside of large airplanes, the resulting savings were immense. It now costs airline companies a lot less to fly their jets.

[used by permission from the Evolution Handbook – pg 66]