Gray Whale Migration Update: April 5, 2000
Our friend Keith "Baja" Jones sent this photo of a baby gray whale, age 4 or 5 weeks. Look carefully at the calf's blowhole. Do you see the barnacles encrusted at the edge of the blowhole? Keith told us: "There is a correlation between how many barnacles the mother has and how many the baby carries." The more barnacles on Mom, more on baby. When you see babies playing and laying on top of the mother whales, you can see that the mothers' barnacles scratch the baby. Find out how barnacles reproduce. Then answer this question:
Farewell, Bubble Blasting Babies
Dear Journey North,
The full moon in March brought with it an exodus of whales. Only 12 single adult whales are left in the lagoon, along with 24 mother/calf pairs. The mothers and calves seem to be swimming against the tidal currents and heading out to the mouth of the lagoon, perhaps to train for their journey north.
This morning I watched a group of three whales for several hours. The mother and calf pair always has another adult companion. This trio has been together since mid February. They spend hours rolling against each other at the surface. Often they hang out with their heads down and their flukes waving in the air. Another mother and calf pair approached the trio. All five whales surfaced together. Then the two calves bubble blasted each other before disappearing under the boat. When the whales surfaced again, they were back in their pair and trio formation. Bottlenose dolphins also play with the calves, jumping and frolicking all around. Scientists doing research on the vocalizations of Gray whale calves recorded this trio. Many sounds were heard underwater with a hydrophone (underwater microphone). The most common sounds these whales produced are popping sounds, which sound like congo drums.
Whale Census: Laguna San Ignacio
Whale spouts are few and far between in the lagoon now. By mid April, all the
whales will be heading north. Good luck following their migration!
Latest Highlights from the Gray Whale Observation Posts
What? No cow/calf pairs yet? The peak of the first migration pulse has passed Monterey without any cow/calf pairs seen. Alisa Schulman-Janiger of the ACS census calls this the doldrums, or the time between the adult and the cow/calf phases of the northward migration. But stay tuned, because that will soon change. Meanwhile, the migration continues northbound with sightings to the middle of Kodiak Island (57.41N,-153.53W). Susan Payne and her reporters are seeing many exuberant whales, with a lot of breaching and lobtailing. Susan also says "Orcas are almost everywhere." Off the coast of Washington at Westport (46.80N,-124.06W), 10-20 grays passed each hour on March 15. Off Tofino, British Columbia (49.11N,125.88W), Rod Palm has seen as many as nine gray whales traveling in a group.
Why is Mike Brittain monitoring a remote hydrophone set up on the north point of Thumb Cove (59.90N, 149.33W)? What can you see through the video camera at the website of Nelson Lagoon School on the Alaska Peninsula (55.92N, 161.35 W)? What's on the agenda for the 4th annual Whale Fest Kodiak? After reading the description in Susan's full report, you'll wish you were heading for the Whale Fest--and you'll find the answers to Challenge Questions #13 and #14, too!
Muktuk With Mustard, Please
Ms. Gaugin's 2nd, 3rd and 4th grade students have this to say about muktuk:
The Skinny on Fat
What's in store for the whales after leaving the warm tropical waters of Mexico's lagoons? Colder water, for one thing. The normal internal temperature of these mammals is about 37 to 38 degrees C (96 to 99 degrees F). But at the northern end of the migration trail, the whales swim in water that is only 3 to 4 degrees C (37 ó39 degrees F). What prevents their bodies from losing precious heat?
If you said blubber, you're right. Gray whales are insulated from the cold outside water by approximately five inches of insulating blubber. You may be surprised that blubber is NOT pure fat. It is a complex mix of fibrous, fatty, and connective tissues honeycombed with large oil-filled cells. Pregnant females have the thickest layers of blubber because they have precious fetuses to protect.
Blubber is so effective at keeping whales warm that even after death, the rate of cooling is very slow. In the book Gray Whales, Wandering Giants, Robert H. Busch writes: "Scientists once put a thermometer in a dead finback whale and were surprised to find twenty-eight hours later that the muscle temperature had dropped only 1.5 degrees. In fact, dead whales often explode from the trapped internal heat combined with the heat generated by decomposition, and exploding carcasses were part of the risks taken by early whalers."
Blubber isn't the only adaptation that helps whales stay warm. A gray whale's arteries and veins lie side by side. As a result, cooled blood from the surface is warmed before it goes to the heart. Whales also have a low ratio of surface area to body volume, which means a relatively small area is available to heat loss. Finally, eating a diet of protein-rich seafood is another way to generate warmth. During its five-month feast on the Arctic feeding grounds, an adult gray will likely swallow at least 76 tons of food.
See for yourself how fat helps sea mammals--and you--stay warm:
Keeping Track: Response to Challenge Question #10:
Last time we asked: "Using the census data, how many adults would you estimate for the time period shown? How many mother/calf pairs? How many calves? Give a range and the average number in your answer."
Adults: From 145 to 196. Average 164.
Spring Training: Response to Challenge Question #11
"Why would mothers teach their calves to swim against the tidal current?" Swimming against the tidal current helps to strengthen the calves, preparing them for their long swim north. Calves, being weaker swimmers, could also get into trouble by being swept out of the mouth of the lagoon with an outgoing tide, or stranded in the upper lagoon during an incoming tide.
How to Respond to Today's Challenge Questions:
Please answer ONLY ONE question in EACH e-mail message.
1. Address an e-mail message to: email@example.com
2. In the Subject Line of your message write: Challenge Question #12 (or #13 or #14).
3. In the body of EACH message, give your answer to ONE of the questions above.
The Next Gray Whale Migration Update Will Be Posted on April 19, 2000.
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