论文部分内容阅读
星期天,小丽跟舅舅到蚯蚓养殖场参观,看见养殖场的工人叔叔正从蚯蚓养殖床里取蚯蚓,然后再投放饲料。取出来的蚯蚓放在木箱内,准备运到养鸡场去喂鸡;有的蚯蚓爬到地上,小丽好奇地问舅舅:“蚯蚓没有脚,为什么会走呢”?舅舅笑着回答:“蚯蚓身体是一节节的,在每一节之间有深槽,如果我们用放大镜仔细观察,就可以发现在每节上生有刚毛,蚯蚓在爬行时刚毛可以支撑它的身体。”舅舅一边说,一边指着一条正在爬行的蚯蚓说:“你瞧,蚯蚓在爬行时,前端先伸长,再用刚毛附着在地上,把后端拖向前进。这样反复收缩和引伸运动,成波浪形逐渐向前移动。据生物学家观察,这种移动
On Sunday, Mary and her uncle visited the earthworm farm and saw that the worker's uncle from the farm was taking earthworms from the earthworm breeding bed before feeding the feed. Take out the earthworms on the wooden box, ready to be transported to the chicken farm to feed the chicken; some earthworms climbed to the ground, Mary curiously asked uncle: ”earthworms have no feet, why go?“? Answer: ”Earthworms body is a section, there are deep grooves in each section, if we look carefully with a magnifying glass, you can find that in each section has a bristle, earthworms crawling when bristles can support its body “Uncle said, pointing to a crawling earthworm and saying,” Look, when the earthworm crawls, the front is lengthened and the bristles are attached to the ground, dragging the back end forward. Extensional movements progressively move forward in waves, which biologists observe