10 Invertebrates-Mid

Invertebrates Written by Brooke Bessesen

无脊椎动物布鲁克·贝森著

Introduction Invertebrates are "spineless" animals. That means they have no backbone, or spine. Run your hand down the center of your back. Do you feel those bumps? The bones of your spine are called vertebrae (VER-tuh-bray). Animals with a spine are called vertebrates. Humans are vertebrates But most animals are invertebrates. They don't have a spine.

无脊椎动物是“没有脊椎”的动物。 这意味着它们没有脊梁。 把你的手顺着背部的中心滑下来。 你感觉到那些肿块了吗?脊椎的骨头叫做椎骨(VER-tuh-bray)。 有脊椎的动物叫做脊椎动物。 人是脊椎动物，但大多数动物是无脊椎动物。 他们没有脊梁骨。

What Do Invertebrates Have in Common? Invertebrates come in many shapes, yet they have a lot in common. You already know they have no spine, but they share other traits, too: Like all animals, invertebrates have more than one cell. Most invertebrates can move from one place to another. Others stay in one place but move their body parts. Invertebrates don't have lungs. They get oxygen through tiny holes on their body or through gills.

无脊椎动物有什么共同之处? 无脊椎动物有很多形状，但它们有很多共同点。 你已经知道它们没有脊椎，但它们也有其他特征:像所有动物一样，无脊椎动物有不止一个细胞。 大多数无脊椎动物都能从一个地方移动到另一个地方。 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。 它们通过身体上的小孔或鳃获取氧气。

Most invertebrates have symmetry. That means the two sides of their body look alike. Some have a center point. Any line through that center will make matching halves. Invertebrates can't make their own body heat. They are cold-blooded. Most invertebrates produce young with sperm from males and eggs from females. Invertebrates must eat food for energy. In this book, you will learn about some groups of invertebrates and how they move and eat. You will also learn a few other traits of each group.

大多数无脊椎动物都有对称性。 这意味着他们身体的两边看起来很像。 有些有一个中心点。任何穿过这个中心的线都将构成相配的两半。 无脊椎动物不能自己产生体温。 他们是冷血动物。大多数无脊椎动物用雄性的精子和雌性的卵子来繁殖后代。 无脊椎动物必须从食物中获取能量。 在这本书中，你将了解一些无脊椎动物群体以及它们如何移动和进食。 你还将了解到每个群体的其他一些特征。

Classifying Invertebrates Invertebrates have traits in common, but they have many differences, too. A fruit fly is smaller than a grain of rice. 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 A crab crawls on the seafloor. Earth has more than a million kinds of invertebrates Imagine the variety! Word Wise Each type of animal has a common name. and a scientific name Apis mellifera is the scientific name for a honeybee.

无脊椎动物有共同的特征，但也有许多不同之处。 果蝇比一粒米还小。 巨型乌贼身长可达17米(55英尺)，眼睛比篮球还大!蜈蚣吃虫子，蝴蝶喝花蜜。 一只蚊子在空中飞，一只螃蟹在海底爬行。 地球上有一百多万种无脊椎动物，想想有多丰富!每一种动物都有一个共同的名字。 学名Apis mellifera是蜜蜂的学名。

Animals look and act in different ways. Scientists classify them by common traits. They classify animals as either vertebrates or invertebrates. Each group has many smaller groups. As you read about these groups, think about why certain invertebrates are placed in the same group. 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

动物的外表和行为方式各不相同。 科学家根据它们的共同特征对它们进行分类。 他们把动物分为脊椎动物和无脊椎动物。 每个小组都有许多更小的小组。 当你读到这些分类时，想想为什么某些无脊椎动物被放在同一个组里。 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