Subject: Re: Killer whales

Pieter Folkens (animalbytes@earthlink.net)
Wed, 26 Feb 1997 01:02:36 -0700

>My Daughter is doing a science fair project, and would like to know some
>good references on how whales are able to propell them selves out of the
>water so high, when they weigh so much.  Could you please help us out?

She is getting into a very sophisticated realm of cetacean anatomical
adaptations. The references are in dry and highly technical academic
publications. I'll try to simplify it as much as possible.

1) The whale tail is a huge set of muscles. If you were to compare the tail
of the terrestrial ancestors of whales to the tail of the blue whale in
terms of muscle power, it would be similar to comparing the relative horse
power of the Wright Flyer at Kitty Hawk to the engines of an F-14 Tomcat.
In both comparisons, the primitive condition was in line to evolve into the
derived condition, but the advanced power is in the orders of magnitude
greater. Whales are significantly heavier than their ancesors as is the
F-14 over the Wright Flyer. That extra weight is spent in the mechanics
which create more power.

2) When a whale puts power to the tail for propulsion much of the energy
could be wasted in friction (drag) and inefficiency. However, the whale has
a few anatomical tricks. The caudal peduncle of the whale at the area where
the flexion of the tail is the greatest is relatively thin vertically. This
allows the tail to move vertically through the water more efficiently than
a long flat paddle so the horizontal flukes at the end of the tail can have
the greatest propulsive effect. Add to this the shape of the flukes. Most
whales have a median notch and pointed tips. Other whales (sperm whales)
have rounded tips and a flap at the median notch. Humpback whales have an
uneven trailing edge. All of these adaptations reduce drag and improve
laminar flow over the flukes, thus increasing the efficiency of the flukes.

3) Moving the flukes up creates (though vector forces) a forward motion.
But not all of this energy makes it into the forward motion. To compensate
partly for this potential loss, whales have evolved a special "tendonous
sheath" over several muscle groups in the tail. This sheath absorbs some of
the energy which is released at the apex of the power stroke. This gives
the tail a sudden thrust as the tail goes from the up stroke into the down
stroke when the power thrust is most effective. This improves the
efficiency of the swimming motion and gives the whale a spring-loaded like
thrust when it needs it the most.

So to answer your question, it is a combination of massive opposing muscles
delivering energy efficiently to a dynamically designed propulsion
mechanism (flukes) with features which reduce drag and improve power
delivery.

By the way, I designed the morphology for the whale models for the Free
Willy films. We purposely followed nature's design for realism. We were
amazed at how efficient that design was. Relatively small actuators
(motors) could propel our animatronic robots. As our designs advanced with
each successive film we were almost able to get our models to do a full
breach. We made the dolphins for the film, White Squal. In that film our
dolphin robots did actually jump out of the water using actuators no larger
than a carton of milk.

Sufficient power and efficient design. That does it.

Cheers,

Pieter Folkens

   \\|
    \|
     Y                         _
    ,~------------------------/ \___^___^._
    |            ~ ~.~ ~.~.~.~.~.~.~.~.~.'~`^--^_,''/
    |          @  _ ~,~.~'~.~,~'~.~,~.~ ~ ~ ~ ~.~  {
    \_________   \_l ~,~,~,~,~,~'.~.____'-----'__`  \
 ~ ~  `----------------------\__'--'              `  \
~ ~                                                 `