1 Vertebrates-Low

Vertebrates Written by Kira Freed

脊椎动物作者:基拉·弗里德

Introduction Knock on your head. The hard thing you feel inside your head is bone. Bones hold up your body. They also protect your brain, heart, and other organs. We can sort animals into two groups. Vertebrates have backbones. Invertebrates do not have backbones. Let's learn about the five groups of vertebrates.

敲你的头。 你脑袋里硬的东西是骨头。 骨头支撑着你的身体。它们还能保护你的大脑、心脏和其他器官。 我们可以把动物分成两类。 脊椎动物有脊骨。 无脊椎动物没有脊椎。 让我们来了解一下这五类脊椎动物。

What Are Bones? All bones are made of a hard kind of body tissue. (Skin and muscles are other kinds of tissue.) Without bone tissue, your body would just be a big, soft blob. The bones inside your body are alive. Some bone cells help your bones heal if one breaks. Other bone cells make blood cells. These bone cells are found in special tissue in the middle of some large bones.

骨头是什么?所有的骨头都是由一种坚硬的身体组织构成的。 (皮肤和肌肉是另外两种组织。)没有骨组织，你的身体就只是一个又大又软的一团。 你身体里的骨头是活的。 一些骨细胞可以帮助你的骨头愈合。 其他骨细胞制造血细胞。 这些骨细胞存在于一些大型骨骼中间的特殊组织中。

The skeleton supports and protects a vertebrate's body. All vertebrates have a spine, or backbone. The spine is like a chain of bones. At the top of the spine is the skull. It holds and protects the brain. Your skeleton has 206 bones. Other kinds of vertebrates have different numbers of bones.

骨骼支撑和保护脊椎动物的身体。 所有的脊椎动物都有脊椎。 脊椎就像一串骨头。 脊椎的顶部是头骨。 它支撑并保护大脑。 你的骨骼有206块骨头。 其他种类的脊椎动物有不同数量的骨头。

The ends of many bones are covered with cartilage. Cartilage is soft tissue that keeps bones from rubbing against each other. Other body parts have cartilage, too. Your nose and ears are made of cartilage. Joints are the places where bones meet. Different joints move in different ways. Cartilage helps all these joints to move.

许多骨头的末端都覆盖着软骨。 软骨是防止骨头相互摩擦的软组织。 身体的其他部位也有软骨。 你的鼻子和耳朵是由软骨组成的。 关节是骨头接合的地方。 不同的关节以不同的方式运动。 软骨帮助所有关节活动。

Different bones have different jobs. Leg bones hold up an animal while it walks or runs. Most flying vertebrates have hollow bones that do not weigh much. The small bones in feet and hands help animals to use tools and get food.

不同的骨头有不同的功能。 腿骨支撑着动物行走或奔跑。 大多数会飞的脊椎动物都有中空的骨头，重量不重。 脚和手上的小骨头帮助动物使用工具和获取食物。