檢視硬骨鱼的原始碼

[[File:硬骨鱼.jpg|缩略图|[https://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=%E7%A1%AC%E9%AA%A8%E9%B1%BC%20%20%20%E6%90%9C%E7%8B%90&step_word=&hs=0&pn=1&spn=0&di=44120&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=2&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=-1&cs=2128617863%2C2489699541&os=906423162%2C347848887&simid=4263143900%2C718609137&adpicid=0&lpn=0&ln=420&fr=&fmq=1631049853677_R&fm=result&ic=&s=undefined&hd=&latest=&copyright=&se=&sme=&tab=0&width=&height=&face=undefined&ist=&jit=&cg=&bdtype=15&oriquery=&objurl=https%3A%2F%2Fgimg2.baidu.com%2Fimage_search%2Fsrc%3Dhttp%3A%2F%2F5b0988e595225.cdn.sohucs.com%2Fimages%2F20171207%2F3575e83b06514e69a240b488e6001cea.jpeg%26refer%3Dhttp%3A%2F%2F5b0988e595225.cdn.sohucs.com%26app%3D2002%26size%3Df9999%2C10000%26q%3Da80%26n%3D0%26g%3D0n%26fmt%3Djpeg%3Fsec%3D1633642058%26t%3D3ae1e3a36efb5d9be446a3678b3878d2&fromurl=ippr_z2C%24qAzdH3FAzdH3F4p_z%26e3Bf5i7_z%26e3Bv54AzdH3Fda808da0AzdH3Fgcd9cmcd98_z%26e3Bfip4s&gsm=2&rpstart=0&rpnum=0&islist=&querylist=&nojc=undefined 原图链接][https://www.sohu.com/a/208968836_384269 来自搜狐]]]
'''硬骨鱼'''鱼类是古老的脊椎动物。它们几乎栖居于地球上所有的水生环境——从淡水的湖泊、河流到咸水的大海和大洋。4.5 亿年前寒武纪时期出现在地球上有圆嘴无颌的鱼。鱼类很容易从外表上区分开来，它们组成了脊椎动物中最大的类群：在总数为5万种的脊椎动物中，鱼类有2万2千余种。鱼类的骨骼按性质分软骨和硬骨两类。