科学：小学教师指南/食物链

食物链（食物网）是指生物之间的一种等级序列，每个生物都依赖于下一个生物作为食物来源。它是指生态系统中生物进食的顺序。食物链是生态系统中食物能量从一个生物体传递到另一个生物体的路径。

能量是完成工作或引起变化所需的。食物链中所有能量的来源都是太阳。
太阳 - 我们太阳系的中心恒星，为地球提供热量和光线。

你知道吗？食物链最早由 9 世纪的阿拉伯裔非洲科学家和哲学家阿尔-贾希兹提出，后来在查尔斯·埃尔顿 1927 年出版的一本书中广为人知，该书还介绍了食物网的概念。

食物链长度

食物链的长度是一个连续变量，它提供了能量传递的度量和生态结构的指标，其值随着从最低营养级到最高营养级线性连接的增加而增加。食物链经常用于生态建模（例如三物种食物链）。它们是对真实食物网的简化抽象，但在其动态和数学意义上很复杂。生态学家已经制定并检验了关于与食物链长度相关的生态模式性质的假设，例如随着生态系统规模的增加而增加的长度、每个连续水平能量的减少，或者长食物链长度不稳定的命题。食物链研究在生态毒理学研究中起着重要作用，追踪环境污染物的途径和生物放大作用。

生产者

also known as autotrophs, is an organism that uses sunlight to make its own food for energy. They make up the first level of every food chain. Autotrophs are usually plants or one-celled organisms. Nearly all autotrophs use a process called photosynthesis to create “food” (a nutrient called glucose) from sunlight, carbon dioxide, and water.Plants are the most familiar type of autotroph, but there are many other kinds. Algae, whose larger forms are known as seaweed, are autotrophic. Phytoplankton, tiny organisms that live in the ocean, are also autotrophs. Some types of bacteria are autotrophs. For example, bacteria living in active volcanoes use sulfur compounds to produce their own food. This process is called chemosynthesis.

消费者

Are the living organism who will depend on other organism to survive. The second trophic level consists of organisms that eat the producers. These are called primary consumers, or herbivores. Deer, turtles, and many types of birds are herbivores. Secondary consumers eat the herbivores. Tertiary consumers eat the secondary consumers. There may be more levels of consumers before a chain finally reaches its top predator. Top predators, also called apex predators, eat other consumers. Consumers can be carnivores (animals that eat other animals) or omnivores (animals that eat both plants and animals). Omnivores, like humans, consume many types of foods. Humans eat plants, such as vegetables and fruits. We also eat animals and animal products, such as meat, milk, and eggs. We eat fungi, such as mushrooms. We also eat algae, in edible seaweeds like nori (used to wrap sushi rolls) and sea lettuce (used in salads).

分解者

Are the living organism (bacteria) that will break down other living organism. Detritivores and decomposers are the final part of food chains. Detritivores are organisms that eat nonliving plant and animal remains. For example, scavengers such as vultures eat dead animals. Dung beetles eat animal feces. Decomposers like fungi and bacteria complete the food chain. They turn organic wastes, such as decaying plants, into inorganic materials, such as nutrient-rich soil. Decomposers complete the cycle of life, returning nutrients to the soil or oceans for use by autotrophs. This starts a whole new food chain.

食物链中能量流动的示例。

太阳给草提供能量
草给老鼠提供能量
老鼠给蛇提供能量
蛇给鹰提供能量
死亡的动物和植物给蚯蚓（分解者）提供能量

生产者 = 植物

消费者 = 老鼠

分解者 = 细菌

例如，草从阳光中获取自身食物。兔子吃草。狐狸吃兔子。当狐狸死亡时，细菌会分解它的尸体，并将其返回土壤，为草等植物提供养分。

任何特定的物种可能会吃一种食物或多种物种，消费者可能会以相似的生物为食。仓鸮可能会吃老鼠；老鼠可能被麻雀鹰、蛇或任何其他众多肉食性动物吃掉。

植物是食物链中的第一级，被称为初级生产者。植物和蔬菜通过光合作用过程制造自己的食物和能量。植物通过利用阳光、空气中的二氧化碳和土壤中的水，并将它们转化为糖的形式来制造自己的食物。消费者有三个等级，初级消费者是指以植物为食的生物，是食物链中的食草动物。次级消费者吃初级消费者。老鼠可能是初级消费者，而猫可能是次级消费者，还有第三级消费者被称为三级消费者，它们是以次级消费者和初级消费者为食的。狼可能是三级消费者，它吃猫和老鼠。

分解者会分解死物中的营养物质并将它们返回土壤。生产者然后可以利用土壤中的营养物质和元素。分解者完成了系统，将必要的分子返回给生产者。