proctal fin的用法和樣例：
例句
- Old World freshwater catfishes having naked skin and a long anal fin more or less merged with the eellike caudal fin.
東半球的淡水鲇魚(yú)，體表無(wú)鱗，有類(lèi)似鰻魚(yú)尾鰭的很長(cháng)的臀鰭。 - The male shows elongated rays in its anal fin and yellow pearl organs on the jaws and opercula during breeding season.
雄魚(yú)的臀鰭鰭條特長(cháng)，交配季節兩頜和鰓蓋會(huì )長(cháng)出黃色的珠星。
