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也许,人们会说鱼都是有鳞的,因为鱼要靠鳞来保护它们的体躯,好似人们要穿衣服一样。人的衣著,各式各样,多姿多彩,鱼的鳞片也各有不同,有圆鳞、栉鳞、硬鳞、盾鳞之分。大多数鱼确都长着各式各样的鳞,可是有些鱼类是没有鳞片的,例如淡水鱼中的鲶类,在鱼类分类学上被列为“鲶形目”。这些无鳞的鱼是怎样保护自己体躯的呢?原来在它们的皮肤中有一种能分泌粘液的腺体,好象人的汗腺出汗一样,如果遇到外来
Perhaps people will say that fish are scaly because fish rely on scales to protect their bodies as if they were to wear clothes. People’s clothing, a wide range of colorful, fish scales are also different, a round scales, scales, scales, shield scales of points. Most fish do have a variety of scales, but some fish are scaly, for example, catfish in freshwater fish are classified as “catfish” in fish taxonomy. How do these scales-free fish protect their body? Originally there was a gland that secreted mucus in their skin, as if sweating like human sweat,