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(Bio) Crocodile Hearts

 
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adedios
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PostPosted: Fri Oct 20, 2006 11:00 pm    Post subject: (Bio) Crocodile Hearts Reply with quote






Crocodile Hearts

Carolyn Gramling
25 October 2006

Crocodiles may not cry real tears, but they do have special hearts.

Like mammal and bird hearts, a crocodile's heart is a muscle that pumps blood. One side of the heart sends blood that is full of oxygen out to most of the body. The other side pulls blood back toward the lungs to give it an oxygen refill.

But crocodile (and alligator) hearts have an extra valve that mammal and bird hearts don't have. The extra valve is a flap that the animal can close in order to keep blood from flowing toward the lungs. This means that the blood goes right back into the body instead.

Although scientists have known about the crocodile heart's extra valve for many years, they haven't known what it was for. Some scientists thought that it might help crocodiles and alligators stay underwater longer, making them better, more deadly hunters.

For the full article:

http://www.sciencenewsforkids....../Note2.asp

*************************************************************

Questions to explore further this topic:

What are crocodiles, alligators, caiman?

http://www.sandiegozoo.org/ani.....odile.html
http://en.wikipedia.org/wiki/Crocodile
http://www.vanaqua.org/educati.....lians.html
http://www.serioussilver.com/t.....gator.html

Lesson Plans on crocodiles

http://school.discovery.com/le.....rocodiles/
http://www.nationalgeographic......gator.html
http://www.nationalgeographic......cseat.html
http://coe.west.asu.edu/studen.....ources.htm

A list of crocodilian species

http://www.flmnh.ufl.edu/cnhc/csl.html

Evolution and taxonomy of crocodiles

http://www.flmnh.ufl.edu/cnhc/cbd-evo.htm

Morphology of crocodiles

http://www.flmnh.ufl.edu/cnhc/cbd-mor.htm

Biological and physiological adaptations of crocodiles

http://www.flmnh.ufl.edu/cnhc/cbd-gen.htm

Conservation issues of crocodiles

http://www.flmnh.ufl.edu/cnhc/cbd-con.htm

What are american crocodiles?

http://www.kidsplanet.org/fact.....odile.html
http://www.flmnh.ufl.edu/cnhc/csp_cacu.htm

What are philippine crocodiles?

http://www.zoo.org.au/conserva.....eature.htm
http://www.flmnh.ufl.edu/cnhc/csp_cmin.htm
http://en.wikipedia.org/wiki/Philippine_Crocodile

Crocodile Management Zone in the province of Isabela, Philippines

http://www.cvped.org/croc.php
http://www.waypoints.ph/index......rphanparm=

The Human Heart

http://www.cincinnatichildrens.....dia/intro/

GAMES

http://www.pbs.org/wnet/nature.....flash.html
http://www.billybear4kids.com/.....gator.html
http://www.pbs.org/wnet/nature/fun.html


Last edited by adedios on Sat Jan 27, 2007 3:52 pm; edited 2 times in total
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adedios
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PostPosted: Mon Nov 27, 2006 11:16 am    Post subject: Global Warming Could Doom Male Crocodiles Reply with quote

Global Warming Could Doom Male Crocodiles

By LiveScience Staff

posted: 27 November 2006
09:53 am ET

Rising temperatures could force the birth of more female crocodiles and fewer males, an expert said today. The scenario could cause some croc populations to disappear.

Crocodile gender is determined by temperature during incubation. Nest temperatures of 89.6 to 91.4 degrees Fahrenheit (32-33 Celsius) result in males. Anything warmer or cooler produces females. Temperatures typically vary from the top of a nest to the bottom, producing both genders.

"A difference of 0.5 - 1º [Celsius] in incubation temperature results in markedly different sex ratios," said Alison Leslie, of South Africa’s University of Stellenbosch. "More female hatchlings due to the cooler or hotter incubation temperatures could lead to eventual extirpation of the species from an area."

Scientists generally agree that the planet is warming and will continue to do so for decades to come.

For the full article:

http://www.livescience.com/ani.....crocs.html
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PostPosted: Mon Mar 19, 2007 9:27 am    Post subject: By crockie, what long, needlepoint teeth you have Reply with quote

University of Oregon
19 March 2007

By crockie, what long, needlepoint teeth you have

Jurassic crocodile is unearthed from the Blue Mountains in eastern Oregon


EUGENE, Ore. --An ancient sea-going crocodile has surfaced from the rocks of Crook County in eastern Oregon. Really.

It's discovery by the North American Research Group (NARG), whose members were digging for Jurassic-age mollusks known as ammonites, is another confirmation that the Blue Mountains consist of rocks that traveled from somewhere in the Far East, says retired University of Oregon geologist William Orr, who was called in to examine the find for the state.

For the full article:

http://www.eurekalert.org/pub_.....031907.php
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PostPosted: Wed Mar 21, 2007 6:53 am    Post subject: American Croc No Longer Near Extinction Reply with quote

American Croc No Longer Near Extinction

By Brian Skoloff
Associated Press
posted: 20 March 2007
05:58 pm ET

WEST PALM BEACH, Fla. (AP) — The U.S. Fish and Wildlife Service declassified the American crocodile as an endangered species Tuesday, saying the animal has rebounded from the edge of extinction.

The reptile remains protected under the federal Endangered Species Act even though it was downgraded to a “threatened'' species, making it illegal to harass, poach or kill the reptiles.

“It's just one step closer to recovery, but it still has many, many threats,'' Fish and Wildlife Service spokesman Tom MacKenzie said. “It's still protected with the full force of federal law.''

The crocodile was on the brink of disappearing from South Florida, its only U.S. habitat, when it was originally listed as a federally endangered species in 1975. By 1976, the population was estimated at just about 300. Scientists now estimate there are up to 2,000 American crocodiles in Florida.

For the full article:

http://www.livescience.com/ani....._croc.html
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PostPosted: Thu Mar 22, 2007 9:41 am    Post subject: Jurassic Crocodile Unearthed in Oregon Reply with quote

Jurassic Crocodile Unearthed in Oregon

By Jeanna Bryner
LiveScience Staff Writer
posted: 21 March 2007
11:58 am ET


The fossil of an ancient amphibious reptile with a crocodile's body and a fish's tail has been unearthed in Oregon. Scientists believe the creature's remains were transported by geologic processes nearly 5,000 miles away from where it originally died more than 100 million years ago.

The new fossil is the oldest crocodilian ever unearthed in Oregon and one of the few to be unearthed on this side of the Pacific. The “hybrid” animal is thought to be a new species within the genus Thalattosuchia, a group of crocodilians living during the age of dinosaurs.

The reptile roamed a tropical environment in Asia about 142 to 208 million years ago. Called a Thalattosuchian, the amphibious creature [image] represents an early milestone in evolutionary history, marking a transition during which these reptiles moved from being semi-aquatic to wholly ocean species.

For the full article:

http://www.livescience.com/ani....._croc.html
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PostPosted: Wed Oct 03, 2007 1:50 pm    Post subject: Researchers: No faking it, crocodile tears are real Reply with quote

Researchers: No faking it, crocodile tears are real
University of Florida

Filed under Research, Sciences on Wednesday, October 3, 2007.GAINESVILLE, Fla. — When someone feigns sadness they “cry crocodile tears,” a phrase that comes from an old myth that the animals cry while eating.

Now, a University of Florida researcher has concluded that crocodiles really do bawl while banqueting – but for physiological reasons rather than rascally reptilian remorse.

UF zoologist Kent Vliet observed and videotaped four captive caimans and three alligators, both close relatives of the crocodile, while eating on a spit of dry land at Florida’s St. Augustine Alligator Farm Zoological Park.

He found that five of the seven animals teared up as they tore into their food, with some of their eyes even frothing and bubbling.

“There are a lot of references in general literature to crocodiles feeding and crying, but it’s almost entirely anecdotal,” Vliet said. “And from the biological perspective there is quite a bit of confusion on the subject in the scientific literature, so we decided to take a closer look.”

A paper about the research appears in the latest edition of the journal BioScience.

Vliet said he began the project after a call from D. Malcolm Shaner, a consultant in neurology at Kaiser Permanente, West Los Angeles, and an associate clinical professor of neurology at the University of California, Los Angeles.

Shaner, who co-authored the paper, was investigating a relatively rare syndrome associated with human facial palsy that causes sufferers to cry while eating. For a presentation he planned to give at a conference of clinical neurologists, he wanted to know if physicians’ general term for the syndrome, crocodile tears, had any basis in biological fact.

Shaner and Vliet uncovered numerous references to crocodile tears in books published from hundreds of years ago to the present.

The term may have gained wide popularity as a result of a passage in one book, “The Voyage and Travel of Sir John Mandeville,” first published in 1400 and read widely, they write.

Says the passage, “In that country be a general plenty of crocodiles …These serpents slay men and they eat them weeping.”

Shaner and Vliet also found reference to crocodiles crying in scientific literature, but it was contradictory or confusing, to say the least.

One scientist, working early last century, decided to try to determine if the myth was true by rubbing onion and salt into crocodiles’ eyes. Shaner said. When they didn’t tear up, he wrongly concluded it was false. As Shaner said, “The problem with those experiments was that he did not examine them when they were eating. He just put onion and salt on their eyes.”

As a result, Vliet decided to do his own observations.

In the myth, crocodiles often cry while eating humans. However, deadpanned Shaner, “we were not able to feed a person to the crocodiles.”

Instead, Vliet had to settle for the dog biscuit-like alligator food that is the staple at the St. Augustine alligator farm. He decided to observe alligators and caimans, rather than crocodiles, because they are trained at the farm to feed on dry land. That’s critical to seeing the tearing because in water the animals’ eyes would be wet anyway.

The farm’s keepers don’t train the crocodiles to feed on land because they are so agile and aggressive, Vliet said. But he said he feels sure they would have the same reaction as alligators and caimans, because all are closely related crocodilians.

What causes the tears remains a bit of a mystery.

Vliet said he believes they may occur as a result of the animals hissing and huffing, a behavior that often accompanies feeding. Air forced through the sinuses may mix with tears in the crocodiles’ lacrimal, or tear, glands emptying into the eye.

But one thing is sure: faux grief is not a factor. “In my experience,” Vliet said, “when crocodiles take something into their mouth, they mean it.”
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PostPosted: Tue Mar 25, 2008 1:58 pm    Post subject: Diving, Rolling, and Floating, Alligator Style Reply with quote

Diving, Rolling, and Floating, Alligator Style
Jennifer Cutraro

March 26, 2008

Try to wrestle an alligator underwater, and you'll probably lose. It's not just that the average gator—at 11 feet long and close to 1,000 pounds—is a whole lot bigger than you are. It turns out alligators have a secret weapon when it comes to moving up, down, and around in the water. Nobody recognized it until now, but alligators actually move their lungs to help them dive, surface, and roll.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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PostPosted: Mon Apr 14, 2008 2:22 pm    Post subject: Antibiotic Alligator: Promising proteins lurk in reptile blo Reply with quote

Week of April 12, 2008; Vol. 173, No. 15 , p. 228

Antibiotic Alligator: Promising proteins lurk in reptile blood
Rachel Ehrenberg

Researchers hunting for new antibiotics might get some aid from gator blood. Scientists are zeroing in on snippets of proteins found in American alligator blood that kill a wide range of disease-causing microbes and bacteria, including the formidable MRSA or methicillin-resistant Staphylococcus aureus.

For the full article:

http://sciencenews.org/articles/20080412/fob2.asp
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