LOOK OUT: Jaws and Teeth for Animals on the Defense Take a Deep Breath Before You Panic Getting enough oxygen across their gills is important for all fish. Some sharks use a process called ram ventilation to get extra oxygen. To do this, they swim fast with their mouths open. So if you're diving or snorkeling in the ocean and see a shark underwater with a wide-open mouth headed your way, you may not need to worry. If you're on top of the water and see an open-mouthed tiger shark headed your way, it might be time to say look out! My, What Big Teeth You Have! Crocodiles and alligators often rest with their mouths wide open. This behavior is called gaping. Gaping may also serve as a threat, showing the size of jaws and teeth to rivals. Gaping, Not Yawning Crocodiles and alligators also use gaping to lower their body temperatures. As ectotherms, they need the sun's energy for heat. Ectotherms are animals that need outside heat sources such as the sun to warm their bodies. Excerpted from Animals That Make Me Say Look Out! (National Wildlife Federation) by Dawn Cusick All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
