All About Sharks From Tooth To Tail 鲨鱼知识百科_图书大全
All About Sharks From Tooth To Tail 鲨鱼知识百科
ISBN: 9780439808842
出版年: 2005-12
页数: 38
定价: 32.50元
内容简介
The Inside Scoop on Sharks
Blood, guts, muscles, and more… that’s what’s inside a shark. Like all animals, sharks have a brain, heart, stomach, intestines, and other organs. But they have some parts that are different, too.
Vertebral Column: A shark’s backbone extends into the top part of its tail fin. This stiff fin helps sharks speed through the water!
Brain: A shark’s brain controls all of a shark’s actions, just like how your brain controls your actions. A lot of a shark’s brain is used for its senses, including smell and sight. You’ll learn more about a shark’s super senses on pages 23 and 24.
Liver: A shark’s liver is filled with oil. Oil is lighter than water, so a shark’s large liver helps it stay afloat.
Gills: Sharks use blood-filled gills to absorb oxygen out of the water.
Hot Blood or Cold?
Most fish, and most sharks, have blood that is the same temperature as the water around them. So, if the water is cold, their blood is cold. Five kinds of sharks, including great white sharks, like Bruce, have warm blood like you do. These fast-swimming sharks hold onto some of the heat produced by their powerful muscles.
Breathing like a shark
Like all fish, sharks get the oxygen they need from the water. Water flows in through their mouth, across their gills, and out through five to seven gill slits. Blood in their gills draws oxygen out of the water.
Sharks that live on the ocean floor, like nurse sharks, bring water to their gills through holes on the top of their head. This way, their gills aren’t clogged with sand or mud.
