Subject: Blubber, speed, diving, and predators

Jennifer D. Philips (jphilips@soest.hawaii.edu)
Mon, 27 Apr 1998 20:13:24 -1000

>1) What is the maximum % of total body weight that accounts for the
>weight of blubber?
>
>2) What is the maximun speed of and average dolphin?
>
>3) What are the differences between humans and whales which allow whales
>to conserve oxygen when diving underwater?
>
>4) What are the dolphin's greatest predators? Why?
>
>Please email back at fefifofum@ilovechocolate.com
>Thank you very much

Hi!

1)  The whale that I know has the highest percentage of blubber for its
body weight is the Northern right whale.  The blubber of this species takes
up almost 40% of its body weight, though this is the higher than for any
other whale.  I would imagine, though I am not sure, that the percent
weight of blubber for most of the baleen whales, at say the end of the
feeding season, is 20 - 30%, and it decreases as they spend time on their
breeding grounds, not feeding.  I would recommend that you try searching
the web and the Whalenet Site for more info on this.

2)  Dolphins can swim pretty fast when they are riding the bow waves of
large boats, often seen to reach speeds of up to 25 miles/hr.  But when
they are swimming on their own, they can reach speeds of up to 15-20 miles/hr.

3)  This is a good question.  You are right that there are some major
differences between dolphins and humans which allows dolphins to dive for
so long.  One major factor is their ability to conserve oxygen.  So how do
they do this?  First of all, the lungs of dolphins are relatively small,
but they are highly adapted with thousands of very fine aveoli and
capillaries where oxygen is exchanged into the blood.  They also are very
good at making sure each breath is very efficient.  When a dolphin
surfaces, it blows out then breathes back in, each time replacing almost
the entire capacity of their lunds (we definitely do not do this).  Another
adaptation in dolphins is a high amount of a substance called myoglobin in
their muscles.  This substance works as an oxygen store in their muscles,
so that even when the animal is not breathing during a dive, the muscles
are still provided with oxygen and the animal can still swim.  Dolphins are
also be capable of slowing down the systems of their body, such as their
heart rate.  

4)  The main predators of dolphins are sharks (white sharks, especially),
killer whales (orcas), and false killer whales.  

I hope I've answered your questions!  Thanks for emailing Whalenet.

Aloha - 

Jen Philips
jphilips@soest.hawaii.edu
__________________________________

Jennifer D. Philips		
jphilips@soest.hawaii.edu

Marine Mammal Research Program
HIMB, University of Hawaii at Manoa
PO Box 1106			
Kailua, HI  96734
voice:  (808) 247-5063
fax: (808) 247-5831
__________________________________