To: Journey North
From: Anne Smrcina Stellwagen Bank National Marine
Sanctuary
Greetings!
The whales continue to sing on Silver Bank and other southern areas. This is the report I've just received from Carole Carlson, a whale researcher who's name may be familiar with those of you studying The Voyage of the MIMI. Carole will be heading down to the Dominican Republic for several 5-day cruises to Silver Bank.
CHALLENGE QUESTION #26:
"Why do the whales "sing" and do humpbacks sing only in southern waters or up north too?"
(To respond to this question, please follow the instructions at the end of this report.)
Carole is in the middle of a series of whale studies. She was just down near Grenada, where she and other researchers were looking for humpbacks and sperm whales. While humpbacks males and females seem to migrate back north every spring, she notes that the female sperm whales and their calves appear to live in the Caribbean waters year- round (as a "resident population"). Only the males move up north.
It appears that two humpbacks were spotted off Race Point, Provincetown, Rhode Island last week. It's not known if these whales were down in the Caribbean (and the first to migrate north) or if theyspent the winter elsewhere. However, the bulk of the humpbacks still seem to be taking their time down south and enjoying the warm, southern waters.
That leads us to last week's Challenge Question #19.
"Why do the whales go south the have their calves?"
From MAINE:
"We think humpbacks have their calves in the Carribean because it is
warmer." jordan@mainelink.net
From Mrs. Nelson's class:
"We think that the whales migrate to the Caribbean because the
Caribbean is warmer." enelson@cecasun.utc.edu
Good thinking! Here are some ideas scientists have about this:
It appears that whale fetuses grow at a very fast rate while inside the mother. This produces a calf that at birth may measure up to one-quarter of the mother's size. This is important because, in a watery world, heat is easily transported away from the body. (This is why you can get hypothermia in water while suviving nicely in air at the same temperature).
The whales large body size compared to skin surface is a way to conserve body temperature. Also, the rounded body and lack of long appendages (arms, legs, or neck) conserves temperature. However, the calf has very little blubber compared to adult whales. In northern, colder climes, the baby whale would lose too much body heat and die. Therefore, the trip to southern waters brings the mother to a warmer area where the calf can be born and then nurse on the rich mother's milk. Whale milk is over 40% fat (cow's milk is about 4%). As the baby nurses, it builds up its fat (blubber) reserves for the northward migration in the spring. The mother, in turn, loses blubber as it feeds its calf, making the warmer waters more welcome.
Try This!
If you're wondering how fat could keep a whale warm, you can test
this for yourself "first-hand". (Read on and you'll see what I
mean.) This may be a bit messy, but the experience is worth it!
Materials Needed:
Bucket
Ice & water
Rubber gloves
Crisco (vegetable shortening)
1. Fill a large bucket with ice water (3/4 full).
2. Fill a plastic bag with Crisco.
3. Put a rubber glove on one hand. Now put your hand into the
Crisco.
4. Submerge both hands into the bucket of ice water.
* How long can you keep your unprotected hand in the water?
* How long does it take before you can feel the cold through
the fat-insulated hand? How long can you keep this hand in the
water?
5. Put a thermometer inside a glove, then put this into the Crisco. Submerge the thermometer into the water. Record the temperature each minute. Predict how long do you think it will take before the thermometer registers the same tempeature as the ice water.
I hope to have some new reports from the Dominican Republic for you next week. And check out the accompanying article on a Massachusetts whale researcher who has gone out to Hawaii to study humpbacks. Where do you think the Hawaiian humpbacks go in the summer?
Until next week, this is Anne Smrcina signing off.
How to Respond to Challenge Question #26:
1. Send an e-mail message to: jn-challenge@learner.org
2. In the Subject Line write: Challenge Question #26
3. In the Body of your message, give the answer. Please include your school name and state or province so other students will know how to reach you.
The Next Humpback Whale Migration Update Will be Posted on March 13, 1996.
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