To: Journey North
From: Anne Smrcina
Stellwagen Bank National Marine Sanctuary
Greetings and Happy Valentine's Day!
.
This message comes to you from the heart. Actually, it's about a
heart -- the whale heart. I bet you're wondering, "What kind of heart
does a whale have?" And the answer is -- BIG. But, in truth, the
whale's heart and circulatory system follows the same basic pattern as
in most mammals, including humans. The heart, although it's big,
still represents only about 0.5%-0.7% of the whale's body weight.
Curiously, the deeper diving whales tend to have smaller hearts in
proportion to their weight and size than shallower diving whales. In
one study undertaken in 1941 at a California whaling station, five
whales hearts were weighed -- and showed the following results:
Sperm Whale
Length 43 feet
Total weight 86,000 lbs/39,000kg
Heart weight 277 lbs./126kg
Fin Whale
Length 71 feet
Total weight 130,942 lbs/59,394kg (incl. blood and body fluids)
Heart weight 842lbs/382kg
Humpback whales (3 samples)
1) Length 41 feet
Total weight 82,000lbs/37,195kg
Heart weight 472lbs/214kg
2) Length 44 feet
Total weight 88,000lbs/39,916kg
Heart weight 400lbs/181kg
3) Length 45 feet
Total weight 90,000lbs/40,823kg
Heart weight 425lbs/193kg
Getting anatomical measurements from whales is often quite difficult - - it's hard to measure them out in the ocean when they're alive, and when they wash up dead on the beach, it can be a messy, stinky job (This is because the whale's carcass is starting to rot.) The internal organs tend to turn to mush, so a clear picture is not always possible.
Nevertheless, we do know that whales have a four-chambered heart, just like us. The heart pumps the blood through a circulatory system that travels throughout the whale's body. There are left and right ventricles and auricles, a pulmonary artery and vein and an aorta. Among mammals, the whale has the widest heart, and it is slightly flattened dorso-ventrally and rounded at its apex. The muscle walls of the ventricles of several large whales have been measured from 7.6 to 12.7cm (about 3-5 in.) in thickness. Pulse rate has been estimated at 60-140 beats per minute, dropping to 4-15 beats per minute when diving.
The above data comes from an excellent resource book entitled, "Whales of the World" by Spencer Wilkie Tinker. 1988. Honolulu: Bess Press, Inc.
Now that you know about whale hearts, try to calculate the weight of your own heart.
NOTE: For all of you web walkers, there's an excellent site for whale information. It's called WhaleNet and it can be reached at http://whale.simmons.edu/
WhaleNet will be building a database of scientific whale sightings and student-generated information from whalewatches. In addition, the web site is packed with photos, links to sources of whale information, activities, and other information. Check it out. You'll be pleasantly surprised.
Not too much to report on the migration front. The humpbacks are still down in the Caribbean -- but I haven't heard anything yet about numbers of calves or total whales.
I did get a report from a Massachusetts teacher who served as an instructor on the sailing vessel SPIRIT OF MASSACHUSETTS on its winter break voyage to the Caribbean.
Margaret Brumsted noted these sightings:
Jan 12
1 small sperm whale
16 degrees 53 minutes N, 62 degrees 04 minutes W
Jan 15
1 humpback whale
16 degrees 19 minutes N, 61 degrees 53 minutes W
Jan 25
3 finback whales
13 degrees 38 minutes N x 62 degrees 41 minutes W
One night they heard breathing sounds from several whales that seemed to be quite close to the boat, and they also saw lots of dolphins, usually near dusk, playing in the bow wake as they traveled between Grenada and Puerto Rico.
Until next week, this is Anne Smrcina from the Stellwagen Bank National Marine Sanctuary signing off.
The Next Humpback Whale Migration Update Will be Posted on February 21, 1996
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