11 Invertebrates-High

Invertebrates Written by Brooke Bessesen

无脊椎动物布鲁克·贝森著

Introduction Invertebrates are "spineless" animals. Calling them spineless doesn't mean they are always afraid. It means that invertebrates have no backbone, or spine. Run your hand down the center of your back. Do you feel all those bumps? Those are the bones of your spine, and they are called vertebrae (VER-tuh-bray). Animals that have a spine are called vertebrates. Humans are vertebrates. But most animals are invertebrates.

无脊椎动物是“没有脊椎”的动物。 说他们没骨气并不意味着他们总是害怕。 这意味着无脊椎动物没有脊椎。 把你的手顺着背部的中心滑下来。 你感觉到这些凸起了吗? 这些是脊椎的骨头，它们被称为椎骨(VER-tuh-bray)。 有脊椎的动物叫做脊椎动物。 人类是脊椎动物。但是大多数动物都是无脊椎动物。

What Do Invertebrates Have in Common? Invertebrates come in a wide variety of shapes and sizes, yet they have a lot in common. You already know that they have no spine. Invertebrates share several other traits, too: Like vertebrates, invertebrates have more than one cell. Their cells work together to keep them alive. Each cell has a job to do. All invertebrates move in some way. Most move from one location to another. Others stay in one place but move their body parts. Invertebrates don't have lungs, so they don't breathe as we do. They get oxygen through gills or through tiny openings on their body.

无脊椎动物有什么共同之处? 无脊椎动物的形状和大小千差万别，但它们有很多共同之处。 你已经知道他们没有骨气了。 无脊椎动物也有其他一些共同的特征:像脊椎动物一样，无脊椎动物有不止一个细胞。 它们的细胞共同工作以维持生命。 每个细胞都有自己的工作。 所有无脊椎动物都以某种方式移动。 大多数人从一个地方搬到另一个地方。 有些人呆在一个地方，但移动他们的身体部位。 无脊椎动物没有肺，所以它们不像我们一样呼吸。 它们通过鳃或身体上的小孔获取氧气。

Most invertebrates have symmetry. In some, the two sides of their body look just like each other. Others have a center point. If you draw any line through that center, you will have matching halves. Since invertebrates cannot make their own body heat, they are cold-blooded. Most invertebrates reproduce with sperm from the male and eggs from the female. Unlike plants, invertebrates must eat to get energy. They cannot make their own food. In this book, you will learn how some invertebrate groups move and get food. You will also learn some of their special traits.

大多数无脊椎动物都有对称性。 有些人的身体两侧看起来很像对方。 其他的则有一个中心点。 如果你在这个中心上画一条线，你就会得到相同的两半。 因为无脊椎动物不能自己产生体温，所以它们是冷血动物。 大多数无脊椎动物用雄性的精子和雌性的卵子来繁殖。 与植物不同，无脊椎动物必须通过进食来获取能量。 他们不能自己做食物。 在这本书中，你将了解到一些无脊椎动物是如何移动和获取食物的。 你还将了解它们的一些特殊特征。

Classifying Invertebrates Although invertebrates share many traits, each group has tremendous differences. A fruit fly is smaller than a grain of rice, but a giant squid can be 17 meters (55 ft.) long, with eyes bigger than basketballs! Centipedes eat worms, but butterflies drink nectar. A mosquito flies in the air, but a crab crawls on the seafloor. In fact, more than a million kinds of invertebrates live on Earth. Just think of all that diversity! Word Wise Each type of animal has a common name and a scientific name. Apis mellifera is the scientific name for a honeybee.

虽然无脊椎动物有许多共同的特征，但每一组都有巨大的差异。 果蝇比一粒米还小，但巨型鱿鱼可以长达17米(55英尺)，眼睛比篮球还大!蜈蚣吃虫子，蝴蝶喝花蜜。 蚊子在空中飞，而螃蟹在海底爬行。 事实上，地球上生活着一百多万种无脊椎动物。 想想所有的多样性吧!每一种动物都有一个常用的名称和学名。 Apis mellifera是蜜蜂的学名。

Because so many animals look and behave in different ways, scientists have grouped them. First they classify animals as either vertebrates or invertebrates. Scientists have identified about 30 invertebrate groups. Each group contains smaller subgroups. All the animals in a group have similar traits. As you read about some of these groups, try to figure out why certain invertebrates are grouped together. Vertebrates Mammals Birds Reptiles Amphibians Fish Invertebrates Poriferans sponges Cnidarians sea jellies corals sea anemones Echinoderms sea stars sea urchins sand dollars Mollusks octopuses squids snails clams Annelids earthworms Arthropods insects spiders lobsters millipedes These are the invertebrate groups covered in this book

由于许多动物的外貌和行为方式各不相同，科学家们将它们进行了分类。 首先，他们把动物分为脊椎动物和无脊椎动物。 科学家们已经确定了大约30种无脊椎动物。 每个组包含更小的子组。 一个群体中的所有动物都有相似的特征。 当你读到这些分类时，试着弄清楚为什么某些无脊椎动物会被归在一起。 脊椎动物哺乳动物鸟类爬行动物两栖动物鱼类无脊椎动物多孔动物海绵刺皮动物海水母珊瑚海葵棘皮动物海星海胆沙美元软体动物章鱼鱿鱼蜗牛蛤环节动物蚯蚓节肢动物昆虫蜘蛛龙虾千足虫这些都是这本书中涉及的无脊椎动物类群