Subject: Fin Whales

Lindsay J Porter (h9390327@hkucc.hku.hk)
Fri, 28 Nov 1997 02:03:29 +0800

>The following questions are from my 5th grade (10-11 year olds) science
>students who have been studying whales since September.  They are
>looking forward to your answers.  
>
>From Reggie and Neil:  How many times does a humpbacked dolphin eat a
>day?  How long is a humpbacked dolphin?
Dear Reggie and Neil,
During the last four years of observations of humpbacked dolphins,  the
average time spent feeding (or foraging) is approx. 55% of daylight hours.
They don't seem to eat more at any particular time of day - they seem to
feed at the front of the  tide.  That is, as the tide flows and ebbs in and
out of the estuary in which the dolphins live, they too move in and out WITH
the tidal front, eating the fish that are ssociated with this confluence
area.  These observations have only been made in daylight though, night-time
activity is still a bit of a mystery to me.

Newly born dolphins are approx. 100cm and they grow rapidly during their
first year of life.  The largest adult I have come across was 255cm long. 

>
>From Rob, Adam, and Eric: How big is the pink dolphin?
Dear Rob, Adam and Eric,
New born dolphins are approximately 100cm and weigh around 11kg.  Adults are
longer, the biggest I have recorded is 255cm, and proportionally heavier as
they are more robust ('chubby'!).  The adult at 255cm weighed 210kg.

>From Mike and Sean: How many molecules are there in a humpbacked
>dolphin?  Why are humpbacked dolphins pink?
Dear Mike and Sean,
Both of these questions are difficult for me to answer!  Molecules...?  Now,
I immediately thought of DNA molecules - as these are not only the 'building
blocks' of every living organism BUT the number calculated to be in dolphins
is similar to that calculated for humans - which is 10'000'000'000 base
pairs (simplistically, the individual components of a DNA strand) PER
CELL... as this number is too large to imagine, I recall a biology teacher
telling me once that if you placed all your body's cells in a long single
line, they would stretch all the way to the moon and back - nine times!  

And why are they pink?  I must confess, I am still puzzled by this?   It
seems such a bright colour to be.  The dolphins have no other marine species
predating upon them in this particular area, so camouflage is not neccesary
for survival.  Tests on skin from dead animals show that the 'pinkness' is a
loss of pigment (baby humpbacks are born grey) rather than a special pigment
itself.   

>From David and Michael:  How big is a humpbacked dolphin's brain? 
Dear David and Michael,
Marine mammals brains are often compared to human brains as they are complex
and well developed.  The head of an adult dolphin is approximately 50cm long
(that is one fifth of the total length) and the brain weighs approx. 12kg.

>From Anna and Danielle:  How many baby humpbacked dolphins die a year?
Dear Anna and Danielle,
During a three year period, 6, 3, and 9 dolphins were recorded when born -
during this period 10 of these dolphins died, some within one year of being
born - some during the following two years.

>From Melissa and Nina:  How long have humans been studying dolphins?
Dear Melissa and Nina,
The first person to be credited with writing about dolphins was Aristotle,
the Greek philosopher, who lived from 384-322 BC.  Images of whales have
been found carved in the walls of Stone Age caves, which date back to 5000BC

>From Carry and Heather:  How were all the babies killed in 1996?
Dear Carry and Heather,
It was not possible to determine the cause of death for any of the of the
infant dolphins that died in 1996

>From Natalie, Maddy, and Kaitlinn:  How many humpbacked dolphins died
>this year?  What whale makes the loudest echolocation?  What age do
>pink dolphins turn pink?  Could you send us a picture of a pink dolphin?
Dear Natalie, Maddy and Kaitlinn,
To date, 12 dolphins have died this year.
Dolphins begin to turn pink during there first year of life - the dorsal fin
becoming pink first.  Full pinkness - without grey splotches or freckles -
isn't acheived until the dolphins are teenagers or even in their twenties. 
If you send me your address I can send a picture OR if you have a colour
printer I can email an image to you.
The loudest whale vocalisations are made by sperm whales 

>From Torie and Liz:  How old are the humpbacked dolphin's when they
>turn pink?
Dear Torie and Liz,
Dolphin begin to turn pink during their first year of life - the dorsal fin
becoming pink first.  Full pinkness - without grey splotches or freckles -
isn't acheived until the dolphins are teenagers or even in their twenties. 

>From Sam and Toby:  What kind of whales do you see in Scotland?
Dear Sam and Toby,
I worked almost exclusively on the east coast of Scotland, where there are
records of Minke whales, sperm whales, fin whales, humpback whales,   beaked
whales, bottlenose whales, pilot whales and killer whales.  
 
>From Justin and Bobby:  How do you think you can save the pink dolphin?
Dear Justin and Bobby,
There are so many processes in trying to protect a species - from public
awareness and education campaigns to lobbying government.  In Hong Kong the
most pressing issue that CAN be solved is to keep some of the dolphins
habitat intact.  As the coastal area here is being rapidly developed, my
institute, supported by local green groups, has proposed that a large marine
protected area be designated and properly managed so that the dolphins might
have some space to live, sufficient fish to eat and be free from teh dangers
that man incur. Thereafter, the far more difficult task of restoring the
water quality of the area must be started.

Please feel free to write again if you need more answers or wish me to
clarify any points.

with best wishes to you all

Lindsay J. Porter