Whale Adaptations: The Body
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Swimming and Diving Machines
Body and Skin Adaptations:
- A gray whale?s
long, sleek torpedo shape is perfect for swimming and diving with less
drag and more speed.
- The whale's skin
excretes tiny droplets of oil that decrease drag even more. The outer
layer of the skin is shed rapidly, which also helps reduce drag.
- A whale's huge
body size helps whales generate and hold heat. Another way to say this
is: Whales have a low ratio of surface area to body volume, giving them
a relatively small area that is available to heat loss.This is an important
adaptation in the ocean, where icy water can zap away body heat up to
20 times faster than on land.
- Whales can grow
so huge because they live their entire lives in water and need not support
their own weight.
Inside Story: Organs That Work for Whales
- A gray whale's
arteries and veins lie side by side. As a result, cooled blood from
the surface is warmed before it goes to the heart. This adaptation helps
the whales conserve body heat.
- A whale's muscles
have large amounts of myoglobin, a protein that stores oxygen, allowing
long dives and submersion. Whales store 41% of their oxygen in their
muscles, compared to the 13% that humans can store. Whales also have
more blood per unit of body weight than humans, which helps them store
- Whale lungs have
more air cells than human lungs. Whales have two layers of capillaries,
greatly increasing the efficiency of air exchange. Grays are usually
shallow divers. Before they dive, whales take a series of deep breaths
that saturate their pulmonary system with oxygen. For deep dives, a
gray whale may take two or three breaths every minute for three to five
minutes, then plunge into the ocean.
- On deep dives,
a whale's heart rate slows down by half (to only 4 or 5 beats per minute).
The blood flow is restricted. This adaptation means that the whale uses
its oxygen supply very slowly. A gray whale can stay underwater for
up to 25 minutes, but normally it stays under three to five minutes.
- On deep dives,
whales don't have to worry about the "bends" (a painful condition
in which nitrogen and other gases form bubbles in the blood if the diver
comes to the surface too fast). Their blubber absorbs some of the nitrogen
and the rest is trapped by the foamy oil in the nasal sacs and sinuses.
The nitrogen is expelled with this oil when the whale spouts.
- The whale's
rib cage is quite flexible, unlike a human's. The rib cage bends easily
under pressure without breaking.
- A whale's
specialized bone structure helps this massive creature be buoyant. The
hard outer bone covers a spongy web-like inner structure that?s laced
with blood vessels. The gaps between the tissues and vessels are filled
with a marrow high in oil content. (Since oil is lighter than water,
some whale bones by themselves actually can float on water.)
have powerful kidneys to deal with salt water. Marine mammals and sea
birds have had to evolve with a high tolerance of salt in the sea water
they take in when they eat. Because whale blood is similar to the blood
of land mammals (that is, it is not any more salty), a whale's kidneys
must excrete (get rid of) the excess salt through urine.
- A thick
layer of blubber under the skin helps make whales buoyant.
- The blubber
is thick enough (5 or 6 inches) to provide insulation against the freezing
water. A gray whale's normal internal temperature is about 99 degrees
F (38 degrees C). But at the northern end of the migration trail, whales
are often in water that is only 37 to 39 degrees F (3 to 4 degrees C).
Brrrrr! The blubber layer keeps their bodies from losing valuable heat.
Blubber is not pure fat, but a mix of fibrous, fatty, and connective
tissues honeycombed with large oil-filled cells. The thickest layers
of blubber are found in pregnant females because they have precious
unborn babies to protect. Blubber is so good at keeping whales warm
that even after death, their rate of body cooling is very slow.
stores food energy; whales can eat huge amounts of food when and where
food is abundant, and then survive when and where food is scarce. The
blubber supplies energy during migration when the whales eat little
1. Have you ever been in cold weather or playing in snow without a jacket?
You quickly learn that you need the insulation of extra layers of clothing
to stay warm. Try this "hands-on" experiment and you'll see how
their fat layer keeps sea mammals warm:
2. What makes
it possible for animals as huge as whales to easily float and move in
water? Write your ideas, then try these investigations into density and
the properties of salt water. Summarize your new understandings in your
mammals differ in many ways from land mammals. In what ways are land mammals
and underwater mammals similar? What common characteristics qualify both
groups of animals to be called mammals? Make a venn diagram to show your