Subject: Adaptations to marine environment vs. Human Divers

Martine Berube (mberube@ulb.ac.be)
Thu, 21 May 1998 12:54:39 +0200 (MET DST)

Here some answers to your questions. Sorry if I have not answer you faster.

Question - Human divers - must have some kind of protection from cold water
- what do marine mammals use for protection?

Answer: A blubber layer just underneath the skin is made of fat cells and
fibrous connective tissue. Blubber insulates the whale from the cold ocean
water.


Question - Human divers - must have some kind of supplied air to dive; or
can only stay down as long as they can hold their breath - what do marine
mammals do and how long can they stay submerged on one breath? and Human
divers - can only go down so deep and stay down so long - how deep can
marine mammals dive and how long can they stay submerged?

Answer: All marine mammals have special physiological adaptations during a
dive. These adaptations enable a baleen whale to conserve
oxygen while underwater. Baleen whales, like other mammals, have a slower
heart rate while diving. When diving, blood is shunted away from tissues
tolerant of low oxygen levels toward the lungs, heart, and brain, where
oxygen is needed. Compared to terrestrial mammals, baleen whales have twice
the concentration of red blood cells and up to nine times the concentration
of the oxygen-binding protein myoglobin. Myoglobin and red blood cells store
oxygen and provide tissues with oxygen while the whale dives.
Baleen whales are not known to dive regularly to great depths. Dives last
anywhere from 3 to 20 minutes or more depending on the species. However, a
sperm whale can dive as deep as 3200 m but they don't dive as deep all the
time. They can stay down up to one hour.


Question - Human divers - must come up slowy to allow dissolves gases to
exit their blood
- do marine mammals have to come up slowly - why or why not?

Answer: They do not suffer from compressed air-diseases, such as the
"bends," since they do not breathe compressed air when diving.  Because of
this they avoid the problem of absorbing high amounts of nitrogen which
occurs when
previously inhaled compressed air expands at the surface.  When they dive,
their lungs are compressed so that air is forced into the nasal passages,
the windpipe, and air sacs around the lungs, and around the sinuses in the
head. This also prevents the absorption of harmful nitrogen through the
lung wall.
Roughly forty percent of the oxygen is stored in the blood which contains a
high amount of oxygen storage particles called hemoglobin. Even if a marine
mammal is stressed after chase, you will see them taking
several breaths in a row, almost as if they were "panting." This
supercharges their bodies again with oxygen before diving deeply for a
longer period.

Human divers - must use specially designed gear to be at home in the water -
what do marine mammals use?

Answer: I will refer you to this website which gives the general adaptation
to marine environment using as a exemple the killer whale
http://www.bev.net:70/0/Schoolhouse/SeaWorld/killer_whale/adapaqkw.txt

Good luck with your work,
Martine

Martine Berube
Unit of Evolutionary Genetics
Department of Molecular Biology
Free University of Brussels (ULB)
CP 244
Bld du Triomphe
B-1050 Brussels, Belgium
Tel: +32 2 650 5427
Fax: +32 2 650 5421
Email: mberube@ulb.ac.be