Fin foil

Maybe you’ve seen that picture taken by the Sea Shepperds in the Faroe Islands where they’re currently killing dolphins as a traditionnal hobby.

Appart from the disgusting aspect of that image, isn’t it amazing how nature created such perfectly shaped and foiled fins ?   NACA didn’t invent anything…

 

Agreed.

However, nature did not anticipate – nor have time to adapt to – supersonic speed and Mach 5.

(For reference, NACA became NASA.)

Thanks for sharing!

At least dolphins know how to foil there fins properly.

It amazes me that the **Sailfish **has a top speed of 68 mph.

 

That is amazing.  That dorsal fin lays down when it’s jamm’n, doesn’t it? Has to… Mike

That’s my guess that it lays flat at top speeds.  Pretty sure the dorsal fin rays act as sail battens for etension.

The question is which fin(s) has the most impact on tracking/steering.

The tail (caudal) fin definitely generates thrust.

 

Symetrical lunate caudal fin built for speed I was taught. Tunas, dorados, makos, whiteys have it. Maby that sail fin is for display purposes. Mike

Only speculation, but that sail may give high maneuverability for cutting through fish schools while dropping out of warp speed and at low speeds.

Pelvic fins as retractable rudders?

Maybe the adipose fin and anal fin combined work like a surfboard fin at high speeds?

“The sail is normally kept folded down and to the side when swimming, but it may be raised when the sailfish feels threatened or excited, making the fish appear much larger than it actually is. This tactic has also been observed during feeding, when a group of sailfish use their sails to “herd” a school of fish or squid.”

Source : http://en.wikipedia.org/wiki/Sailfish

Makes sense.

The sail is also raised after periods of high activity.  It is believed to help reduce body temperature.

The pelvic fins can be pulled into grooves on the sides.  They are retracted for speed also.