Hello students--
Once again Dr. Standora has sent us new data from the loggerhead transmitters. As usual, be sure to chart the movements of the turtle transmitters and compare them to the movements last week. Do you notice any interesting changes? We sure did! Read on....
In last week's update, we challenged you to consider why data for some of the turtle transmitters was received far more often than data for other transmitters. Thank you to the third graders at Oak Grove School in Lexington, South Carolina for their thoughts about the frequent signals:
"The ones with more signals may just be swimming on top of the water instead of bobbing up and down to breathe." Theresa Harmon (oge@scsn.net)
We asked Dr. Standora to answer this question for us, and we think you will be surprised when you read his answer!!! According to Dr. Standora "The more frequent readings are usually from a free floating transmitter, because the unit's antenna is always at the surface..."
Surprised? We were too! What Dr. Standora is telling us is that these drifting transmitters must have broken off of the turtles!
Signals from loose transmitters are received very frequently because they float. Since they are always at the surface, their signals are picked up each time the satellite orbits overhead (providing the transmitter is "on"). In contrast, signals from a transmitter that is attached to a turtle are not picked up as frequently. This is because when the turtle dives the signal can't travel through salt water.
According to Dr. Standora, three transmitters which we have been tracking appear to have broken off of the turtles and have been drifting. These include:
* Transmitter # 09037 (which broke off about February 6, 1996)
* Transmitter # 09038 (which broke off about November 8, 1995) and
* Transmitter # 09039 ( which broke off about December 30, 1995).
Dr. Standora has another clue which makes him quite certain that 3 of the transmitters are loose. The satellite normally sends him "diving data"-- information about how long the transmitters have been under the water and how deep they were. These 3 transmitters have not been going under water at all according to the readings he is receiving.
Fortunately, Turtle # 11462 continues to send diving data so we can assume this turtle's transmitter is still attached.
Challenge Question # 67
"Why do you think Dr. Standora designed turtle tracking transmitters that would break off turtles easily?"
To respond to this question, please follow the instructions at the end of this report.
A few weeks ago, several students described the Gulf Stream, an important current in the North Atlantic Ocean. This current flows northeast from the United States, towards Europe. Therefore, the movements of the 3 drifting transmitters have given us a "live" demonstration of the path of the Gulf Stream. We hope you've enjoyed discovering this for yourselves.
Now that you have this new information, go back and review the data. How do the travels of TURTLE # 11462 compare to the travels of the 3 drifting transmitters? How does this new information change your views about loggerhead migration? What does this experience show us about assumptions people make based on limited information?
Announcing the Journey North Turtle Transmitter Contest
Before saying good-bye to the 3 wayward transmitters it's time for a contest!
Transmitter # 09037 has been drifting in the Gulf Stream since about February 6, 1996. Where do you think the transmitter is going? How fast is it travelling? Using the latitude and longitude coordinates below, predict where the drifting transmitter will be on March 24th when it will be out of power.
Turtle Transmitter # 09037
Mar. 01: 36.575 N, 68.281 W
Mar. 11: 37.811 N, 65.528 W
Mar. 24: Your Guess !
Challenge Question # 68
"Where do you think the drifting transmitter will be on March 24th, when it is out of power?"
To respond to this question, please follow the instructions at the end of this report.
(The batteries in the loose transmitters wear out faster because they are sending signals more often and are therefore using more power. As a result, the batteries in transmitters # 09038 and # 09039 have already worn out.)
Here is the data from our last travelling turtle:
Turtle #11462
Mar. 15: 39.363N, 49.134W
Mar. 16: 39.010N, 48.153W
Mar. 16: 39.071N, 48.043W
Mar. 17: 39.399N, 48.160W
Mar. 17: 39.431N, 48.205W
Mar. 17: 39.480N, 48.337W
Mar. 18: 39.599N, 48.856W
How to Respond to Challenge Questions # 67 & # 68:
1. Send an e-mail message to jn-challenge@learner.org
2. In the Subject line, write: Challenge Question #67 (or #68) (Please do not answer both Challenge Questions in one message!)
3. In the Body of your message, answer one of these questions:
Challenge Question # 67
"Why do you think Dr. Standora designed turtle tracking transmitters that would break off turtles easily?"
OR
Challenge Question # 68
"Where do you think the drifting transmitter will be on March 24th, when it is out of power?"
The Next Turtle Transmitter and Loggerhead Sea Turtle Migration Update Will be on April 10, 1996
 |
|
|---|
