Crocodile hearts.Crocodiles may not cry real tears, but they do have special hearts. Like mammal mammal, an animal of the highest class of vertebrates, the Mammalia. The female has mammary glands, which secrete milk for the nourishment of the young after birth. 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 refill noun A second allotment of a prescription agent obtained from a pharmacy, which is allowed by the original prescription verb Pharmacology To obtain more of a particular drug, after the initially prescribed amount of the agent has been used or . But crocodile crocodile, large, carnivorous reptile of the order Crocodilia, found in tropical and subtropical regions. Crocodiles live in swamps or on river banks and catch their prey in the water. They have flattened bodies and tails, short legs, and powerful jaws. (and alligator alligator, large aquatic reptile of the genus Alligator, in the same order as the crocodile. There are two species—a large type found in the S United States and a small type found in E China. Alligators differ from crocodiles in several ways. ) hearts have an extra valve that mammal and bird hearts don't have. The extra valve is a flap The communications protocol used by AOL Instant Messenger (AIM). FLAP runs over TCP/IP and provides the header format for transmitting IM commands and data. It includes the SNAC data type, which is the primary data structure transmitted between clients and servers. See OSCAR. 1. 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 ox·tail n. The tail of an ox, especially when used for food. ox  tail 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, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. . 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. |
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