Greetings Turtle Fans--
For all the faithful fans of Turtle # 11462, there is still good news! The loggerhead and the transmitter appear to still be hanging on together, sending out signals all the while. Dr. Standora has sent in the latest data on this dynamic duo, and you can look at the data below. See any unusual changes?
In Challenge Question # 96 from last week's update, we asked you to find out how long loggerheads can hold their breath underwater, and how long can humans. Thanks to Stevie, Sean and Ryan in Mrs. Gardner's class in New York who thought the loggerheads could hold their breath for 20 minutes. Good guess! We asked Dr. Standora this same question and here is what he said."From work we've done off of Cape Canaveral FL several years ago I can say that loggerheads often stayed submerged for about one hour. These animals often concentrated their activity near the thermocline. These times may be different than what it would be for the one we are tracking now. It varies with water depth, temperature, and animal activity (swimming during migration or loafing offshore)."
We learned the longest that humans can hold their breath for is about 2 1/2 minutes, and this is for pearl divers who make a living by holding their breath underwater. Most of us can only hold our breath for 1 minute.
We also asked you in Challenge Question # 97 to guess how much additional pressure there would be on your body if you were 165 feet underwater. Thanks to Megan, Keir and Robbie, third graders at Sonnesyn Elementary School in New Hope, MN, who gave us the correct answer of "FIVE ADDITIONAL ATMOSPHERES!!!" of pressure.
Can't Take the Pressure
Human divers can experience other problems underwater, which turtles are
somehow able to avoid. One problem is called decompression sickness or "the
bends". This happens when a scuba diver comes back up to the surface too
fast.
The problem occurs because whenever a scuba diver breathes his/her air deep underwater from a scuba tank, the diver is under added water pressure. This pressure causes added amounts of nitogen gas from the scuba air to dissolve into the diver's blood. If the diver swims up to the surface too fast, there is suddenly less water pressure on his body, and so the nitrogen gas now tries to escape the diver's blood very quickly in the form of fizzing bubbles. But the bubbles have no where to go and get trapped in the diver's body. This is very painful and can lead to other serious health problems, even death.
Try This
To understand how "the bends" happens, do this experiment. Get a clear
plastic bottle of your favorite carbonated soda (Do not use glass). Before
opening the soda, shake it really well. There is now alot of built up gas
under pressure in the soda.The gases don't escape because the cap keeps
them under pressure. This is just like the diver deep underwater who is
under added water pressure. Now take the soda cap off. The pressure is
suddenly lessened and the gas in the soda tries to escape very
fast...through bubbles. This is exactly what happens inside divers who come
to the surface too fast. Except there is nowhere for the bubbles to go, so
they get trapped in the diver's body.
Why Don't Turtles Get "The Bends?"
We asked Dr. Standora this question and here is his explanation. "Turtles
don't get the bends like scuba divers because they begin their dive with a
given volume of air at surface pressure. When they descend the water
pressure pushes in on their lungs to make the volume smaller. As they
return to the surface, the lungs simply return to their original size and
the air is again at normal pressure."
"Scuba divers on the other hand are breathing air under increased pressure when they are submerged. The air pressure in the divers lungs equals the water pressure at the given depth. If a scuba diver would take a deep breath underwater, hold his breath and then shoot to the surface his lungs would explode because the pressure inside would be much greater than that of the surrounding air at the surface."
"If a diver has been at great depth for an extended amount of time the gases he inhales are in the blood stream, again under pressure equal to the surrounding water, and when the diver returns to the surface these gases will fizz much like when opening a bottle of pop. Depending on where these bubbles become trapped they can be fatal. Divers solve this problem by assending slowly and stopping at predetermined depths for decompression to occur."
Pressures on Survival
We've talked alot about how effortlessly the turtles dive underwater
despite the added pressures. Now its time to talk about another kind of
pressure on the loggerheads--the pressures on their survival. Loggerheads
are considered a threatened species, which means that their population is
in danger if proper conservation steps aren't taken.
There are several pressures caused by man which can result in many loggerhead deaths. One activity that kills thousands of loggerheads each year is commercial shrimping and fishing operations, which use large nets that accidentally drown turtles. Therefore, some laws require shrimping and fishing operations to try to prevent these deaths by using a device called a TED on their nets.
Challenge Question # 103
" What is a TED, and how does it help stop turtle deaths in fishing and shrimping nets?"
(See instructions on how to respond to this the Challenge Question below.)
New Turtle Data
Turtle #11462:
19 April 36.421N 45.795W
19 April 36.377N 45.797W
20 April 36.239N 45.594W
20 April 36.238N 45.559W
20 April 36.200N 45.516W
How to Respond to Challenge Questions # 103:
1. Send an e-mail message to: jn-challenge@learner.org
2. In the Subject Line write: Challenge Question # 103
3. In the Body of your message, answer this question:
" What is a TED, and how does it help stop turtle deaths in fishing and shrimping nets?"
Responses to Challenge Questions:
Challenge Question # 96:
"How long can loggerheads hold their breath underwater--how long can humans?"
From NEW YORK:
We think the turtles can dive down for 20 min.
STEVIE SEAN & RYAN in Mrs. Gardner's class
Macedon Elementary School <macelem@transit.nyser.net>
Challenge Question # 97:
"At 165 feet underwater, how many additional atmospheres of pressure will a
human feel on their body"
From MINNESOTA:
"You told us that if you go 33 feet deep, you add one atmosphere of
pressure. We kept adding 33 feet plus 33 feet until we found that six
times 33 feet is 165 feet. Since you asked how many additional atmospheres
you would feel at 165 feet the answer is six minus one equals FIVE
ADDITIONAL ATMOSPHERES!!!
Megan, Keir and Robbie, Third Graders at Sonnesyn Elementary School in New
Hope, MN, Katie wilson (kwilson@metro2.k12.mn.us)
The Next Loggerhead Sea Turtle Migration Update Will Be Posted on May 8, 1996
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