Printer Friendly

Crocodile hearts.

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.

Now, scientists have a new idea about what a crocodile's heart can do. By studying captive alligators, scientists discovered that the extra valve can reroute some of the blood normally pumped to its lungs to its stomach instead. This diversion lasts about the same amount of time that it takes an alligator to digest a big meal.

To see if the valve is really connected to digestion, the scientists used surgery to close the valve in some captive alligators but left it working in others. They then fed each alligator a meal of hamburger meat and an oxtail bone. Alligators with a working valve digested the tough meal quicker.

Blood returning from the body to the heart has extra carbon dioxide. Carbon dioxide is also a building block of stomach acid, which helps digest food. So, when blood rich with carbon dioxide goes to the stomach instead of the lungs, it can aid digestion.

Whether it helps alligators and crocodiles pursue their underwater prey or helps them digest it, the heart's special valve does seem to give these hunters a leg up on the competition.

http://www.sciencenewsforkids.org/articles/20061025/Note2.asp

From Science News for Kids Oct. 25, 2006.

Copyright (c) 2006 Science Service. All rights reserved.
COPYRIGHT 2006 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2006, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Author:Gramling, Carolyn
Publication:Science News for Kids
Geographic Code:1USA
Date:Oct 25, 2006
Words:356
Previous Article:The science fair circuit.
Next Article:Internet generation.
Topics:


Related Articles
'Weird' crocodile.
Ancient crocodile chomped on plants.
Turtles and crocs: Strange relations.
Big Mouth.
Toothy valves control crocodile hearts.
Fossils indicate ... wow, what a croc!
Here Comes SuperCroc! (Science).
The crocodiles of Danau Sentarum, West Kalimantan.
Crocodile blood kills HIV.
Quirky cardiology: crocs' hearts may aid their digestion.

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters |