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Greetings Gulf Stream Drifters!
Another week has gone by, and so too have the nautical miles for our still- swimming Turtle # 11462. Dr. Standora has sent us the most recent data for this turtle and we've put that data below. Has Turtle # 11462 made any interesting movements or changes in direction since last week?
Over the last two weeks, we challenged you to predict where the drifting,loose transmitter #09037 will end up. Thanks to the students from Scott Young Public School in Ontario, Canada who really swam the distance on this contest question! We have put their answer below.
We also asked physical oceanographer, Ryan Smith of the NOAA's Global Drifter Center about this, and he thought that the transmitter could have a somewhat uncertain future.
"If you compare the list of transmitter fixes for number #09037 with a thermographic image of gulfstream SST you can see that the transmitter is moving with the stream towards Europe. If the transmitter was closer to the eastern coast of North America (between the stream and the coastline), you might be able to pick a location in the U.S. where #09037 would come ashore. However, looking at the data, I would say that this transmitter will not come ashore for quite some time (years, possibly).
The transmitter's last position was still far enough from Europe that it could wind up anywhere from Scotland to Africa. There is also a possibility that #09037 could get caught up in the mid-Atlantic gyre and be brought back towards North America. The transmitter might not wash ashore at all. If it is the same type of ARGOS transmitter that I'm thinking of, it is very small. Though it is floating now, over time with marine growth, it could become heavy enough to sink."
Be sure to surf over to the Global Drifter Center which features real research about ocean currents and weather. Also, did you know that Benjamin Franklin is credited with creating the first chart of the Gulf Stream? He gathered this information from sailors sailing across the Atlantic Ocean and published the first known chart of the Gulf Stream in 1779. Take a look at what wise old Ben discovered and much more at the Find The Gulf Stream Project
We also "dove in" to a new topic for the loggerheads--underwater diving--and we challenged you to learn how deep loggerheads can dive, and how scientists find this out. Thanks to all the students who "took the plunge" and answered these questions. We put their answers below. We also consulted with our expert Dr. Standora on this diving question, and based on previous data from juvenile loggerheads, he said that that "they can dive between 100 to 200 meters! This is pretty amazing for an animal only 50 cm long."
Dr. Standora also explained that scientists use transmitters to find out how deep the loggerheads can dive. "The transmitters can go down to a depth of 3,000 meters before they crush. We have the loggerhead transmitters calibrated to record data down to a depth of 250 meters. The transmitters do not transmit when they are underwater. A saltwater switch turns the unit off if it is submerged. This saves on battery life because high frequency radio waves (401 MHz) do not travel well through sea water. When the turtle returns to the surface and the transmitter antenna breaks the surface, the data which has been stored is transmitted in a short burst. We can record depths to an accuracy of 1 meter."
This week, we will look even deeper into the undersea world of loggerhead diving. To understand just how amazing the turtles are at diving, it helps to stop and think about what happens to humans when they dive underwater.
First, when humans dive underwater, we need to hold our breath (unless we use a scuba tank). Second, we also feel more pressure on our bodies the deeper we go--we usually feel this in our ears. You get the same feeling in your ears when you ride in a car that is driving down from a mountain top or when you ride down from the top of a very tall building in an elevator.
The pressure you feel when you go deeper underwater, however, is much greater because water is 800 times more dense (thicker) than air! For every 33 feet you go underwater, you will add twice the pressure that you normally feel on your body (this is called atmospheric pressure). So, at 33 feet underwater, your body feels the pressure of your normal atmosphere above water PLUS one additional atmosphere. At 66 feet, a human will feel the pressure of 2 additional atmospheres.
For this week's Challenge Questions, we want you to do some more deep thinking about diving.
Challenge Question # 96:
"How long can loggerheads hold their breath underwater--how long can humans?"
OR
Challenge Question # 97:
"At 165 feet underwater, how many additional atmospheres of pressure will a human feel on their body"
(To answer these Challenge Questions, follow the instructions at the bottom of this update.)
New Turtle Data
Turtle #11462:
Apr. 6 36.868N, 44.911W
Apr. 8 36.246N, 44.993W
Apr. 8 36.295N, 44.723W
Apr. 8 36.235N, 44.963W
Responses to Challenge Questions:
Contest Challenge Question # 77
"How fast does the Gulf Stream appear to travel?" and "Where and when do you think the transmitter
# 09037 will reach shore?".
From ONTARIO:
1st we figured out how far the transmitter would go per day, and times that by 111 then divided it by 7 days. Then
we figured out where we think it is going by the way of the currents, on a map of the world. Next we measured how
many miles per inch there were on the map, then we multiplied the number by 1.6 to convert miles into km. Next
we divided the km by the distance to the shore. We think the transmitter will end up in the Bay of Biseay on Oct6/96.
Rose, Ashley, and Stephanie.
Scott Young Public School (syoung@web.apc.org)
Challenge Question # 86
"How deep do you think loggerheads can dive? How do you think scientists find out how deep the loggerheads
dive?
From NEW YORK:
We are fifth grade students at Errick Road School, located in North Tonawanda, NY, which is close to Buffalo, NY
and Niagara Falls, NY. We think that the loggerhead turtles dive approximately 200 feet to get their food.
The scientists use transmitters that send an echo beam, which goes to the satellite, then the scientists can calculate
the depth by using a speed of sound formula.
Mrs. Sterner's fifth grade class at Errick Rd.
our account name is ErrickRd@AOL.Com
From ALASKA:
I think the loggerhead sea turtle can dive about 500 feet below the water. By examening the logger head sea turtle
to find out. I think scientist can find alot.
Kathy Clark (kclark@kpbsd.k12.ak.us)
From ONTARIO:
We think they dive somewhere from 2,450 to16,350 feet. And the scientists know because the turtles swim in the
Atlantic ocean and most of their food is at or near the bottom of the ocean, so the turtles dive down to get their
food.
Sincerly
Rose,Steph,Ashley
Scott Young Public School syoung@web.apc.org
How to Respond to Challenge Questions # 96 or # 97:
1. Send an e-mail message to: jn-challenge@learner.org
2. In the Subject Line write: Challenge Question # 96 (or # 97)
(Please answer only ONE QUESTION in each e-mail message!)
3. In the Body of your message, answer ONE of these questions:
Challenge Question # 96
"How long can loggerheads hold their breath underwater--how long can humans?"
OR
Challenge Question # 97
"At 165 feet underwater, how many additional atmospheres of pressure will a human feel on their body"
The Next Loggerhead Sea Turtle Migration Update Will Be on May 1, 1996
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